1TCSH(1)                   BSD General Commands Manual                  TCSH(1)


4     tcsh — C shell with file name completion and command line editing


7     tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg] ...
8     tcsh -l


11     tcsh is an enhanced but completely compatible version of the Berkeley
12     UNIX C shell, csh(1).  It is a command language interpreter usable both
13     as an interactive login shell and a shell script command processor.  It
14     includes a command-line editor (see The command-line editor (+)), pro‐
15     grammable word completion (see Completion and listing (+)), spelling cor‐
16     rection (see Spelling correction (+)), a history mechanism (see History
17     substitution), job control (see Jobs) and a C-like syntax.  The NEW
18     FEATURES (+) section describes major enhancements of tcsh over csh(1).
19     Throughout this manual, features of tcsh not found in most csh(1) imple‐
20     mentations (specifically, the 4.4BSD csh(1)) are labeled with ‘(+)’, and
21     features which are present in csh(1) but not usually documented are la‐
22     beled with ‘(u)’.
24   Argument list processing
25     If the first argument (argument 0) to the shell is ‘-’ then it is a login
26     shell.  A login shell can be also specified by invoking the shell with
27     the -l flag as the only argument.
29     The rest of the flag arguments are interpreted as follows:
31     -b      Forces a “break” from option processing, causing any further
32             shell arguments to be treated as non-option arguments.  The re‐
33             maining arguments will not be interpreted as shell options.  This
34             may be used to pass options to a shell script without confusion
35             or possible subterfuge.  The shell will not run a set-user ID
36             script without this option.
38     -c      Commands are read from the following argument (which must be
39             present, and must be a single argument), stored in the command
40             shell variable for reference, and executed.  Any remaining argu‐
41             ments are placed in the argv shell variable.
43     -d      The shell loads the directory stack from ~/.cshdirs as described
44             under Startup and shutdown, whether or not it is a login shell.
45             (+)
47     -Dname[=value]
48             Sets the environment variable name to value.  (Domain/OS only)
49             (+)
51     -e      The shell exits if any invoked command terminates abnormally or
52             yields a non-zero exit status.
54     -f      The shell does not load any resource or startup files, or perform
55             any command hashing, and thus starts faster.
57     -F      The shell uses fork(2) instead of vfork(2) to spawn processes.
58             (+)
60     -i      The shell is interactive and prompts for its top-level input,
61             even if it appears to not be a terminal.  Shells are interactive
62             without this option if their inputs and outputs are terminals.
64     -l      The shell is a login shell.  Applicable only if -l is the only
65             flag specified.
67     -m      The shell loads ~/.tcshrc even if it does not belong to the ef‐
68             fective user.  Newer versions of su(1) can pass -m to the shell.
69             (+)
71     -n      The shell parses commands but does not execute them.  This aids
72             in debugging shell scripts.
74     -q      The shell accepts SIGQUIT (see Signal handling) and behaves when
75             it is used under a debugger.  Job control is disabled. (u)
77     -s      Command input is taken from the standard input.
79     -t      The shell reads and executes a single line of input.  A ‘\’ may
80             be used to escape the newline at the end of this line and con‐
81             tinue onto another line.
83     -v      Sets the verbose shell variable, so that command input is echoed
84             after history substitution.
86     -x      Sets the echo shell variable, so that commands are echoed immedi‐
87             ately before execution.
89     -V      Sets the verbose shell variable even before executing ~/.tcshrc.
91     -X      Is to -x as -V is to -v.
93     --help  Print a help message on the standard output and exit. (+)
95     --version
96             Print the version/platform/compilation options on the standard
97             output and exit.  This information is also contained in the
98             version shell variable. (+)
100     After processing of flag arguments, if arguments remain but none of the
101     -c, -i, -s, or -t options were given, the first argument is taken as the
102     name of a file of commands, or “script”, to be executed.  The shell opens
103     this file and saves its name for possible resubstitution by ‘$0’.  Be‐
104     cause many systems use either the standard version 6 or version 7 shells
105     whose shell scripts are not compatible with this shell, the shell uses
106     such a “standard” shell to execute a script whose first character is not
107     a ‘#’, i.e., that does not start with a comment.
109     Remaining arguments are placed in the argv shell variable.
111   Startup and shutdown
112     A login shell begins by executing commands from the system files
113     /etc/csh.cshrc and /etc/csh.login.  It then executes commands from files
114     in the user's home directory: first ~/.tcshrc (+) or, if ~/.tcshrc is not
115     found, ~/.cshrc, then the contents of ~/.history (or the value of the
116     histfile shell variable) are loaded into memory, then ~/.login, and fi‐
117     nally ~/.cshdirs (or the value of the dirsfile shell variable) (+).  The
118     shell may read /etc/csh.login before instead of after /etc/csh.cshrc, and
119     ~/.login before instead of after ~/.tcshrc or ~/.cshrc and ~/.history, if
120     so compiled; see the version shell variable. (+)
122     Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on
123     startup.
125     For examples of startup files, please consult:
126     http://tcshrc.sourceforge.net
128     Commands like stty(1) and tset(1), which need be run only once per login,
129     usually go in one's ~/.login file.  Users who need to use the same set of
130     files with both csh(1) and tcsh can have only a ~/.cshrc which checks for
131     the existence of the tcsh shell variable before using tcsh-specific com‐
132     mands, or can have both a ~/.cshrc and a ~/.tcshrc which sources (see the
133     builtin command) ~/.cshrc.  The rest of this manual uses ~/.tcshrc to
134     mean ~/.tcshrc or, if ~/.tcshrc is not found, ~/.cshrc.
136     In the normal case, the shell begins reading commands from the terminal,
137     prompting with
138           >
140     (Processing of arguments and the use of the shell to process files con‐
141     taining command scripts are described later.)  The shell repeatedly reads
142     a line of command input, breaks it into words, places it on the command
143     history list, parses it and executes each command in the line.
145     One can log out by typing ^D on an empty line, logout or login or via the
146     shell's autologout mechanism (see the autologout shell variable).  When a
147     login shell terminates it sets the logout shell variable to ‘normal’ or
148     ‘automatic’ as appropriate, then executes commands from the files
149     /etc/csh.logout and ~/.logout.  The shell may drop DTR on logout if so
150     compiled; see the version shell variable.
152     The names of the system login and logout files vary from system to system
153     for compatibility with different csh(1) variants; see FILES.
155   Editing
156     We first describe The command-line editor (+).  The Completion and
157     listing (+) and Spelling correction (+) sections describe two sets of
158     functionality that are implemented as editor commands but which deserve
159     their own treatment.  Finally, Editor commands (+) lists and describes
160     the editor commands specific to the shell and their default bindings.
162   The command-line editor (+)
163     Command-line input can be edited using key sequences much like those used
164     in emacs(1) or vi(1).  The editor is active only when the edit shell
165     variable is set, which it is by default in interactive shells.  The
166     bindkey builtin can display and change key bindings to editor commands
167     (see Editor commands (+)).  emacs(1)-style key bindings are used by de‐
168     fault (unless the shell was compiled otherwise; see the version shell
169     variable), but bindkey can change the key bindings to vi(1)-style bind‐
170     ings en masse.
172     The shell always binds the arrow keys (as defined in the TERMCAP environ‐
173     ment variable) to editor commands:
175           Key    Editor command
177           down   down-history
178           up     up-history
179           left   backward-char
180           right  forward-char
182     unless doing so would alter another single-character binding.  One can
183     set the arrow key escape sequences to the empty string with settc to pre‐
184     vent these bindings.  The ANSI/VT100 sequences for arrow keys are always
185     bound.
187     Other key bindings are, for the most part, what emacs(1) and vi(1) users
188     would expect and can easily be displayed by bindkey, so there is no need
189     to list them here.  Likewise, bindkey can list the editor commands with a
190     short description of each.  Certain key bindings have different behavior
191     depending if emacs(1) or vi(1)-style bindings are being used; see vimode
192     for more information.
194     Note that editor commands do not have the same notion of a “word” as does
195     the shell.  The editor delimits words with any non-alphanumeric charac‐
196     ters not in the shell variable wordchars, while the shell recognizes only
197     whitespace and some of the characters with special meanings to it, listed
198     under Lexical structure.
200   Completion and listing (+)
201     The shell is often able to complete words when given a unique abbrevia‐
202     tion.  For example, typing part of a word
203           ls /usr/lost
204     and hit the tab key to run the complete-word editor command.  The shell
205     completes the filename /usr/lost to /usr/lost+found/, replacing the in‐
206     complete word with the complete word in the input buffer.  (Note the ter‐
207     minal ‘/’; completion adds a ‘/’ to the end of completed directories and
208     a space to the end of other completed words, to speed typing and provide
209     a visual indicator of successful completion.  The addsuffix shell vari‐
210     able can be unset to prevent this.)  If no match is found (perhaps
211     /usr/lost+found doesn't exist), the terminal bell rings.  If the word is
212     already complete (perhaps there is a /usr/lost on your system, or perhaps
213     you were thinking too far ahead and typed the whole thing) a ‘/’ or space
214     is added to the end if it isn't already there.
216     Completion works anywhere in the line, not at just the end; completed
217     text pushes the rest of the line to the right.  Completion in the middle
218     of a word often results in leftover characters to the right of the cursor
219     that need to be deleted.
221     Commands and variables can be completed in much the same way.  For exam‐
222     ple, typing
223           em[tab]
224     would complete ‘em’ to ‘emacs’ if ‘emacs’ were the only command on your
225     system beginning with ‘em’.  Completion can find a command in any direc‐
226     tory in path or if given a full pathname.
228     Typing
229           echo $ar[tab]
230     would complete ‘$ar’ to ‘$argv’ if no other variable began with ‘ar’.
232     The shell parses the input buffer to determine whether the word you want
233     to complete should be completed as a filename, command or variable.  The
234     first word in the buffer and the first word following ‘;’, ‘|’, ‘|&’,
235     ‘&&’, or ‘||’ is considered to be a command.  A word beginning with ‘$’
236     is considered to be a variable.  Anything else is a filename.  An empty
237     line is “completed” as a filename.
239     You can list the possible completions of a word at any time by typing ^D
240     to run the delete-char-or-list-or-eof editor command.  The shell lists
241     the possible completions using the ls-F builtin and reprints the prompt
242     and unfinished command line, for example:
244           > ls /usr/l[^D]
245           lbin/       lib/        local/      lost+found/
246           > ls /usr/l
248     If the autolist shell variable is set, the shell lists the remaining
249     choices (if any) whenever completion fails:
251           > set autolist
252           > nm /usr/lib/libt[tab]
253           libtermcap.a@ libtermlib.a@
254           > nm /usr/lib/libterm
256     If the autolist shell variable is set to ‘ambiguous’, choices are listed
257     only when completion fails and adds no new characters to the word being
258     completed.
260     A filename to be completed can contain variables, your own or others'
261     home directories abbreviated with ‘~’ (see Filename substitution) and di‐
262     rectory stack entries abbreviated with ‘=’ (see Directory stack
263     substitution (+)).  For example,
265           > ls ~k[^D]
266           kahn    kas     kellogg
267           > ls ~ke[tab]
268           > ls ~kellogg/
270     or
272           > set local = /usr/local
273           > ls $lo[tab]
274           > ls $local/[^D]
275           bin/ etc/ lib/ man/ src/
276           > ls $local/
278     Note that variables can also be expanded explicitly with the
279     expand-variables editor command.
281     delete-char-or-list-or-eof lists at only the end of the line; in the mid‐
282     dle of a line it deletes the character under the cursor and on an empty
283     line it logs one out or, if the ignoreeof variable is set, does nothing.
284     M-^D, bound to the editor command list-choices, lists completion possi‐
285     bilities anywhere on a line, and list-choices (or any one of the related
286     editor commands that do or don't delete, list and/or log out, listed un‐
287     der delete-char-or-list-or-eof) can be bound to ^D with the bindkey
288     builtin command if so desired.
290     The complete-word-fwd and complete-word-back editor commands (not bound
291     to any keys by default) can be used to cycle up and down through the list
292     of possible completions, replacing the current word with the next or pre‐
293     vious word in the list.
295     The shell variable fignore can be set to a list of suffixes to be ignored
296     by completion.  Consider the following:
298           > ls
299           Makefile        condiments.h~   main.o          side.c
300           README          main.c          meal            side.o
301           condiments.h    main.c~
302           > set fignore = (.o \~)
303           > emacs ma[^D]
304           main.c   main.c~  main.o
305           > emacs ma[tab]
306           > emacs main.c
308     ‘main.c~’ and ‘main.o’ are ignored by completion (but not listing), be‐
309     cause they end in suffixes in fignore.  Note that a ‘\’ was needed in
310     front of ‘~’ to prevent it from being expanded to home as described under
311     Filename substitution.  fignore is ignored if only one completion is pos‐
312     sible.
314     If the complete shell variable is set to ‘enhance’, completion 1) ignores
315     case and 2) considers periods, hyphens and underscores (‘.’, ‘-’, and
316     ‘_’) to be word separators and hyphens and underscores to be equivalent.
317     If you had the following files
319           comp.lang.c      comp.lang.perl   comp.std.c++
320           comp.lang.c++    comp.std.c
322     and typed
323           mail -f c.l.c[tab]
324     it would be completed to
325           mail -f comp.lang.c
326     and typing
327           mail -f c.l.c[^D]
328     would list ‘comp.lang.c’ and ‘comp.lang.c++’.
330     Typing
331           mail -f c..c++[^D]
332     would list ‘comp.lang.c++’ and ‘comp.std.c++’.
334     Typing
335           rm a--file[^D]
336     in the following directory
338           A_silly_file    a-hyphenated-file    another_silly_file
340     would list all three files, because case is ignored and hyphens and un‐
341     derscores are equivalent.  Periods, however, are not equivalent to hy‐
342     phens or underscores.
344     If the complete shell variable is set to ‘Enhance’, completion ignores
345     case and differences between a hyphen and an underscore word separator
346     only when the user types a lowercase character or a hyphen.  Entering an
347     uppercase character or an underscore will not match the corresponding
348     lowercase character or hyphen word separator.
350     Typing
351           rm a--file[^D]
352     in the directory of the previous example would still list all three
353     files, but typing
354           rm A--file
355     would match only ‘A_silly_file’ and typing
356           rm a__file[^D]
357     would match just ‘A_silly_file’ and ‘another_silly_file’ because the user
358     explicitly used an uppercase or an underscore character.
360     Completion and listing are affected by several other shell variables:
361     recexact can be set to complete on the shortest possible unique match,
362     even if more typing might result in a longer match:
364           > ls
365           fodder   foo      food     foonly
366           > set recexact
367           > rm fo[tab]
369     just beeps, because ‘fo’ could expand to ‘fod’ or ‘foo’, but if we type
370     another ‘o’,
372           > rm foo[tab]
373           > rm foo
375     the completion completes on ‘foo’, even though ‘food’ and ‘foonly’ also
376     match.  autoexpand can be set to run the expand-history editor command
377     before each completion attempt, autocorrect can be set to spelling-cor‐
378     rect the word to be completed (see Spelling correction (+)) before each
379     completion attempt and correct can be set to complete commands automati‐
380     cally after one hits return.  matchbeep can be set to make completion
381     beep or not beep in a variety of situations, and nobeep can be set to
382     never beep at all.  nostat can be set to a list of directories and/or
383     patterns that match directories to prevent the completion mechanism from
384     stat(2)ing those directories.  listmax and listmaxrows can be set to
385     limit the number of items and rows (respectively) that are listed without
386     asking first.  recognize_only_executables can be set to make the shell
387     list only executables when listing commands, but it is quite slow.
389     Finally, the complete builtin command can be used to tell the shell how
390     to complete words other than filenames, commands and variables.  Comple‐
391     tion and listing do not work on glob-patterns (see Filename
392     substitution), but the list-glob and expand-glob editor commands perform
393     equivalent functions for glob-patterns.
395   Spelling correction (+)
396     The shell can sometimes correct the spelling of filenames, commands and
397     variable names as well as completing and listing them.
399     Individual words can be spelling-corrected with the spell-word editor
400     command (usually bound to M-s and M-S) and the entire input buffer with
401     spell-line (usually bound to M-$).  The correct shell variable can be set
402     to ‘cmd’ to correct the command name or ‘all’ to correct the entire line
403     each time return is typed, and autocorrect can be set to correct the word
404     to be completed before each completion attempt.
406     When spelling correction is invoked in any of these ways and the shell
407     thinks that any part of the command line is misspelled, it prompts with
408     the corrected line:
410           > set correct = cmd
411           > lz /usr/bin
412           CORRECT>ls /usr/bin (y|n|e|a)?
414     One can answer ‘y’ or space to execute the corrected line, ‘e’ to leave
415     the uncorrected command in the input buffer, ‘a’ to abort the command as
416     if ^C had been hit, and anything else to execute the original line un‐
417     changed.
419     Spelling correction recognizes user-defined completions (see the complete
420     builtin command).  If an input word in a position for which a completion
421     is defined resembles a word in the completion list, spelling correction
422     registers a misspelling and suggests the latter word as a correction.
423     However, if the input word does not match any of the possible completions
424     for that position, spelling correction does not register a misspelling.
426     Like completion, spelling correction works anywhere in the line, pushing
427     the rest of the line to the right and possibly leaving extra characters
428     to the right of the cursor.
430   Editor commands (+)
431     bindkey lists key bindings and bindkey -l lists and briefly describes ed‐
432     itor commands.  Only new or especially interesting editor commands are
433     described here.  See emacs(1) and vi(1) for descriptions of each editor's
434     key bindings.
436     The character or characters to which each command is bound by default is
437     given in parentheses.  ^character means a control character and
438     M-character a meta character, typed as escape-character (or ^[character)
439     on terminals without a meta key.  Case counts, but commands that are
440     bound to letters by default are bound to both lower- and uppercase let‐
441     ters for convenience.
443     Supported editor commands are:
445     backward-char (^B, left)
446             Move back a character.  Cursor behavior modified by vimode.
448     backward-delete-word (M-^H, M-^?)
449             Cut from beginning of current word to cursor - saved in cut buf‐
450             fer.  Word boundary behavior modified by vimode.
452     backward-word (M-b, M-B)
453             Move to beginning of current word.  Word boundary and cursor be‐
454             havior modified by vimode.
456     beginning-of-line (^A, home)
457             Move to beginning of line.  Cursor behavior modified by vimode.
459     capitalize-word (M-c, M-C)
460             Capitalize the characters from cursor to end of current word.
461             Word boundary behavior modified by vimode.
463     complete-word (tab)
464             Completes a word as described under Completion and listing (+).
466     complete-word-back (not bound)
467             Like complete-word-fwd, but steps up from the end of the list.
469     complete-word-fwd (not bound)
470             Replaces the current word with the first word in the list of pos‐
471             sible completions.  May be repeated to step down through the
472             list.  At the end of the list, beeps and reverts to the incom‐
473             plete word.
475     complete-word-raw (^X-tab)
476             Like complete-word, but ignores user-defined completions.
478     copy-prev-word (M-^_)
479             Copies the previous word in the current line into the input buf‐
480             fer.  See also insert-last-word.  Word boundary behavior modified
481             by vimode.
483     dabbrev-expand (M-/)
484             Expands the current word to the most recent preceding one for
485             which the current is a leading substring, wrapping around the
486             history list (once) if necessary.  Repeating dabbrev-expand with‐
487             out any intervening typing changes to the next previous word
488             etc., skipping identical matches much like
489             history-search-backward does.
491     delete-char (not bound)
492             Deletes the character under the cursor.  See also
493             delete-char-or-list-or-eof.  Cursor behavior modified by vimode.
495     delete-char-or-eof (not bound)
496             Does delete-char if there is a character under the cursor or
497             end-of-file on an empty line.  See also
498             delete-char-or-list-or-eof.  Cursor behavior modified by vimode.
500     delete-char-or-list (not bound)
501             Does delete-char if there is a character under the cursor or
502             list-choices at the end of the line.  See also
503             delete-char-or-list-or-eof.
505     delete-char-or-list-or-eof (^D)
506             Does delete-char if there is a character under the cursor,
507             list-choices at the end of the line or end-of-file on an empty
508             line.  See also those three commands, each of which does only a
509             single action, and delete-char-or-eof, delete-char-or-list, and
510             list-or-eof, each of which does a different two out of the three.
512     delete-word (M-d, M-D)
513             Cut from cursor to end of current word - save in cut buffer.
514             Word boundary behavior modified by vimode.
516     down-history (down, ^N)
517             Like up-history, but steps down, stopping at the original input
518             line.
520     downcase-word (M-l, M-L)
521             Lowercase the characters from cursor to end of current word.
522             Word boundary behavior modified by vimode.
524     end-of-file (not bound)
525             Signals an end of file, causing the shell to exit unless the
526             ignoreeof shell variable is set to prevent this.  See also
527             delete-char-or-list-or-eof.
529     end-of-line (^E, end)
530             Move cursor to end of line.  Cursor behavior modified by vimode.
532     expand-history (M-space)
533             Expands history substitutions in the current word.  See History
534             substitution.  See also magic-space, toggle-literal-history, and
535             the autoexpand shell variable.
537     expand-glob (^X-*)
538             Expands the glob-pattern to the left of the cursor.  See Filename
539             substitution.
541     expand-line (not bound)
542             Like expand-history, but expands history substitutions in each
543             word in the input buffer.
545     expand-variables (^X-$)
546             Expands the variable to the left of the cursor.  See Variable
547             substitution.
549     forward-char (^F, right)
550             Move forward one character.  Cursor behavior modified by vimode.
552     forward-word (M-f, M-F)
553             Move forward to end of current word.  Word boundary and cursor
554             behavior modified by vimode.
556     history-search-backward (M-p, M-P)
557             Searches backwards through the history list for a command begin‐
558             ning with the current contents of the input buffer up to the cur‐
559             sor and copies it into the input buffer.  The search string may
560             be a glob-pattern (see Filename substitution) containing ‘*’,
561             ‘?’, ‘[]’, or ‘{}’.  up-history and down-history will proceed
562             from the appropriate point in the history list.  Emacs mode only.
563             See also history-search-forward and i-search-back.
565     history-search-forward (M-n, M-N)
566             Like history-search-backward, but searches forward.
568     i-search-back (not bound)
569             Searches backward like history-search-backward, copies the first
570             match into the input buffer with the cursor positioned at the end
571             of the pattern, and prompts with
572                   bck:
573             and the first match.  Additional characters may be typed to ex‐
574             tend the search, i-search-back may be typed to continue searching
575             with the same pattern, wrapping around the history list if neces‐
576             sary, (i-search-back must be bound to a single character for this
577             to work) or one of the following special characters may be typed:
579                   Key     Behavior
581                   ^W      Appends the rest of the word under the cursor to
582                           the search pattern.
584                   delete (or any character bound to backward-delete-char)
585                           Undoes the effect of the last character typed and
586                           deletes a character from the search pattern if ap‐
587                           propriate.
589                   ^G      If the previous search was successful, aborts the
590                           entire search.  If not, goes back to the last suc‐
591                           cessful search.
593                   escape  Ends the search, leaving the current line in the
594                           input buffer.
596             Any other character not bound to self-insert-command terminates
597             the search, leaving the current line in the input buffer, and is
598             then interpreted as normal input.  In particular, a carriage re‐
599             turn causes the current line to be executed.  See also
600             i-search-fwd and history-search-backward.  Word boundary behavior
601             modified by vimode.
603     i-search-fwd (not bound)
604             Like i-search-back, but searches forward.  Word boundary behavior
605             modified by vimode.
607     insert-last-word (M-_)
608             Inserts the last word of the previous input line (‘!$’) into the
609             input buffer.  See also copy-prev-word.
611     list-choices (M-^D)
612             Lists completion possibilities as described under Completion and
613             listing (+).  See also delete-char-or-list-or-eof and
614             list-choices-raw.
616     list-choices-raw (^X-^D)
617             Like list-choices, but ignores user-defined completions.
619     list-glob (^X-g, ^X-G)
620             Lists (via the ls-F builtin) matches to the glob-pattern (see
621             Filename substitution) to the left of the cursor.
623     list-or-eof (not bound)
624             Does list-choices or end-of-file on an empty line.  See also
625             delete-char-or-list-or-eof.
627     magic-space (not bound)
628             Expands history substitutions in the current line, like
629             expand-history, and inserts a space.  magic-space is designed to
630             be bound to the space bar, but is not bound by default.
632     normalize-command (^X-?)
633             Searches for the current word in PATH and, if it is found, re‐
634             places it with the full path to the executable.  Special charac‐
635             ters are quoted.  Aliases are expanded and quoted but commands
636             within aliases are not.  This command is useful with commands
637             that take commands as arguments, e.g., ‘dbx’ and ‘sh -x’.
639     normalize-path (^X-n, ^X-N)
640             Expands the current word as described under the ‘expand’ setting
641             of the symlinks shell variable.
643     overwrite-mode (unbound)
644             Toggles between input and overwrite modes.
646     run-fg-editor (M-^Z)
647             Saves the current input line and looks for a stopped job where
648             the file name portion of its first word is found in the editors
649             shell variable.  If editors is not set, then the file name por‐
650             tion of the EDITOR environment variable (‘ed’ if unset) and the
651             VISUAL environment variable (‘vi’ if unset) will be used.  If
652             such a job is found, it is restarted as if ‘fg %job’ had been
653             typed.  This is used to toggle back and forth between an editor
654             and the shell easily.  Some people bind this command to ^Z so
655             they can do this even more easily.
657     run-help (M-h, M-H)
658             Searches for documentation on the current command, using the same
659             notion of “current command” as the completion routines, and
660             prints it.  There is no way to use a pager; run-help is designed
661             for short help files.  If the special alias helpcommand is de‐
662             fined, it is run with the command name as a sole argument.  Else,
663             documentation should be in a file named command.help, command.1,
664             command.6, command.8, or command, which should be in one of the
665             directories listed in the HPATH environment variable.  If there
666             is more than one help file only the first is printed.
668     self-insert-command (text characters)
669             In insert mode (the default), inserts the typed character into
670             the input line after the character under the cursor.  In over‐
671             write mode, replaces the character under the cursor with the
672             typed character.  The input mode is normally preserved between
673             lines, but the inputmode shell variable can be set to ‘insert’ or
674             ‘overwrite’ to put the editor in that mode at the beginning of
675             each line.  See also overwrite-mode.
677     sequence-lead-in (arrow prefix, meta prefix, ^X)
678             Indicates that the following characters are part of a multi-key
679             sequence.  Binding a command to a multi-key sequence really cre‐
680             ates two bindings: the first character to sequence-lead-in and
681             the whole sequence to the command.  All sequences beginning with
682             a character bound to sequence-lead-in are effectively bound to
683             undefined-key unless bound to another command.
685     spell-line (M-$)
686             Attempts to correct the spelling of each word in the input buf‐
687             fer, like spell-word, but ignores words whose first character is
688             one of ‘-’, ‘!’, ‘^’, or ‘%’, or which contain ‘\’, ‘*’, or ‘?’,
689             to avoid problems with switches, substitutions and the like.  See
690             Spelling correction (+).
692     spell-word (M-s, M-S)
693             Attempts to correct the spelling of the current word as described
694             under Spelling correction (+).  Checks each component of a word
695             which appears to be a pathname.
697     toggle-literal-history (M-r, M-R)
698             Expands or unexpands history substitutions in the input buffer.
699             See also expand-history and the autoexpand shell variable.
701     undefined-key (any unbound key)
702             Beeps.
704     up-history (up, ^P)
705             Copies the previous entry in the history list into the input buf‐
706             fer.  If histlit is set, uses the literal form of the entry.  May
707             be repeated to step up through the history list, stopping at the
708             top.
710     upcase-word (M-u, M-U)
711             Uppercase the characters from cursor to end of current word.
712             Word boundary behavior modified by vimode.
714     vi-beginning-of-next-word (not bound)
715             Vi goto the beginning of next word.  Word boundary and cursor be‐
716             havior modified by vimode.
718     vi-eword (not bound)
719             Vi move to the end of the current word.  Word boundary behavior
720             modified by vimode.
722     vi-search-back (?)
723             Prompts with
724                   ?
725             for a search string (which may be a glob-pattern, as with
726             history-search-backward), searches for it and copies it into the
727             input buffer.  The bell rings if no match is found.  Hitting re‐
728             turn ends the search and leaves the last match in the input buf‐
729             fer.  Hitting escape ends the search and executes the match.  vi
730             mode only.
732     vi-search-fwd (/)
733             Like vi-search-back, but searches forward.
735     which-command (M-?)
736             Does a which (see the description of the builtin command) on the
737             first word of the input buffer.
739     yank-pop (M-y)
740             When executed immediately after a yank or another yank-pop, re‐
741             places the yanked string with the next previous string from the
742             killring.  This also has the effect of rotating the killring,
743             such that this string will be considered the most recently killed
744             by a later yank command.  Repeating yank-pop will cycle through
745             the killring any number of times.
747   Lexical structure
748     The shell splits input lines into words at blanks and tabs.  The special
749     characters ‘&’, ‘|’, ‘;’, ‘<’, ‘>’, ‘(’, and ‘)’, and the doubled charac‐
750     ters ‘&&’, ‘||’, ‘<<’, and ‘>>’ are always separate words, whether or not
751     they are surrounded by whitespace.
753     When the shell's input is not a terminal, the character ‘#’ is taken to
754     begin a comment.  Each ‘#’ and the rest of the input line on which it ap‐
755     pears is discarded before further parsing.
757     A special character (including a blank or tab) may be prevented from hav‐
758     ing its special meaning, and possibly made part of another word, by pre‐
759     ceding it with a backslash (‘\’) or enclosing it in single (‘'’), double
760     (‘"’), or backward (‘`’) quotes.  When not otherwise quoted a newline
761     preceded by a ‘\’ is equivalent to a blank, but inside quotes this se‐
762     quence results in a newline.
764     Furthermore, all Substitutions except History substitution can be pre‐
765     vented by enclosing the strings (or parts of strings) in which they ap‐
766     pear with single quotes or by quoting the crucial character(s) (e.g., ‘$’
767     or ‘`’ for Variable substitution or Command substitution respectively)
768     with ‘\’.  (Alias substitution is no exception: quoting in any way any
769     character of a word for which an alias has been defined prevents substi‐
770     tution of the alias.  The usual way of quoting an alias is to precede it
771     with a backslash.)  History substitution is prevented by backslashes but
772     not by single quotes.  Strings quoted with double or backward quotes un‐
773     dergo Variable substitution and Command substitution, but other substitu‐
774     tions are prevented.
776     Text inside single or double quotes becomes a single word (or part of
777     one).  Metacharacters in these strings, including blanks and tabs, do not
778     form separate words.  Only in one special case (see Command substitution)
779     can a double-quoted string yield parts of more than one word; single-
780     quoted strings never do.  Backward quotes are special: they signal
781     Command substitution, which may result in more than one word.
783     C-style escape sequences can be used in single quoted strings by preced‐
784     ing the leading quote with ‘$’.  (+) See Escape sequences (+) for a com‐
785     plete list of recognized escape sequences.
787     Quoting complex strings, particularly strings which themselves contain
788     quoting characters, can be confusing.  Remember that quotes need not be
789     used as they are in human writing!  It may be easier to quote not an en‐
790     tire string, but only those parts of the string which need quoting, using
791     different types of quoting to do so if appropriate.
793     The backslash_quote shell variable can be set to make backslashes always
794     quote ‘\’, ‘'’, and ‘"’ (+).  This may make complex quoting tasks easier,
795     but it can cause syntax errors in csh(1) scripts.
797   Escape sequences (+)
798     The following escape sequences are always recognized inside a string con‐
799     structed using ‘$''’, and optionally by the echo builtin command as con‐
800     trolled by the echo_style shell variable.
802     Supported escape sequences are:
804           Escape        Description
806           \a            Bell.
808           \b            Backspace.
810           \cc           The control character denoted by ‘^c’ in stty(1).  If
811                         c is a backslash, it must be doubled.
813           \e            Escape.
815           \f            Form feed.
817           \n            Newline.
819           \r            Carriage return.
821           \t            Horizontal tab.
823           \v            Vertical tab.
825           \\            Literal backslash.
827           \'            Literal single quote.
829           \"            Literal double quote.
831           \nnn          The character corresponding to the octal number nnn.
833           \xnn          The character corresponding to the hexadecimal number
834                         nn (1-2 hexadecimal digits).
836           \x{nnnnnnnn}  The character corresponding to the hexadecimal number
837                         nnnnnnnn (1-8 hexadecimal digits).
839           \unnnn        The Unicode code point nnnn (1-4 hexadecimal digits).
841           \Unnnnnnnn    The Unicode code point nnnnnnnn (1-8 hexadecimal dig‐
842                         its).
844     The implementations of ‘\x’, ‘\u’, and ‘\U’ in other shells may take a
845     varying number of digits.  It is often safest to use leading zeros to
846     provide the maximum expected number of digits.
848   Substitutions
849     We now describe the various transformations the shell performs on the in‐
850     put in the order in which they occur.  We note in passing the data struc‐
851     tures involved and the commands and variables which affect them.  Remem‐
852     ber that substitutions can be prevented by quoting as described under
853     Lexical structure.
855   History substitution
856     Each command, or “event”, input from the terminal is saved in the history
857     list.  The previous command is always saved, and the history shell vari‐
858     able can be set to a number to save that many commands.  The histdup
859     shell variable can be set to not save duplicate events or consecutive du‐
860     plicate events.
862     Saved commands are numbered sequentially from 1 and stamped with the
863     time.  It is not usually necessary to use event numbers, but the current
864     event number can be made part of the prompt by placing an ‘!’ in the
865     prompt shell variable.
867     By default history entries are displayed by printing each parsed token
868     separated by space; thus the redirection operator ‘>&!’ will be displayed
869     as ‘> & !’.  The shell actually saves history in expanded and literal
870     (unexpanded) forms.  If the histlit shell variable is set, commands that
871     display and store history use the literal form.
873     The history builtin command can print, store in a file, restore and clear
874     the history list at any time, and the savehist and histfile shell vari‐
875     ables can be set to store the history list automatically on logout and
876     restore it on login.
878     History substitutions introduce words from the history list into the in‐
879     put stream, making it easy to repeat commands, repeat arguments of a pre‐
880     vious command in the current command, or fix spelling mistakes in the
881     previous command with little typing and a high degree of confidence.
883     History substitutions begin with the character ‘!’.  They may begin any‐
884     where in the input stream, but they do not nest.  The ‘!’ may be preceded
885     by a ‘\’ to prevent its special meaning; for convenience, a ‘!’ is passed
886     unchanged when it is followed by a blank, tab, newline, ‘=’ or ‘(’.
888     History substitutions also occur when an input line begins with ‘^’; see
889     History substitution abbreviation.
891     The characters used to signal history substitution (‘!’ and ‘^’) can be
892     changed by setting the histchars shell variable.  Any input line which
893     contains a history substitution is printed before it is executed.
895     A history substitution may have an “event specification” (see History
896     event specification), which indicates the event from which words are to
897     be taken, a “word designator” (see History word designators), which se‐
898     lects particular words from the chosen event, and/or a “word modifier”
899     (see History word modifiers), which manipulates the selected words.
901   History event specification
902     A history event specification may be one of (with the history substitu‐
903     tion character ‘!’ shown):
905           !Event  History event specification
907           !n      A number, referring to a particular event.
909           !-n     An offset, referring to the event n before the current
910                   event.
912           !#      The current event.  This should be used carefully in
913                   csh(1), where there is no check for recursion.  tcsh allows
914                   10 levels of recursion. (+)
916           !!      The previous event, equivalent to ‘!-1’.
918           !s      The most recent event whose first word begins with the
919                   string s.
921           !?s?    The most recent event which contains the string s.  The
922                   second ‘?’ can be omitted if it is immediately followed by
923                   a newline.
925     For example, consider this bit of someone's history list:
927            9  8:30    nroff -man wumpus.man
928           10  8:31    cp wumpus.man wumpus.man.old
929           11  8:36    vi wumpus.man
930           12  8:37    diff wumpus.man.old wumpus.man
932     The commands are shown with their event numbers and time stamps.  The
933     current event, which we haven't typed in yet, is event 13.
935     Typing
936           !11
937     or
938           !-2
939     refers to event 11.
941     Typing
942           !!
943     refers to the previous event, 12.  ‘!!’ can be abbreviated ‘!’ if it is
944     followed by ‘:’, which is described in History word designators and
945     History word modifiers.
947     Typing
948           !n
949     refers to event 9, which begins with ‘n’.
951     Typing
952           !?old?
953     refers to event 12, which contains ‘old’.
955     Without word designators or modifiers history references simply expand to
956     the entire event, so we might type
957           !cp
958     to redo the ‘cp’ command (event 10) or
959           !!|more
960     if the ‘diff’ output in the previous event, 12, scrolled off the top of
961     the screen.
963     History references may be insulated from the surrounding text with braces
964     (‘{’ and ‘}’) if necessary.  For example,
965           !vdoc
966     would look for a command beginning with ‘vdoc’, and, in this example, not
967     find one, but
968           !{v}doc
969     would expand unambiguously to ‘vi wumpus.mandoc’ by matching event 11.
970     Even in braces, history substitutions do not nest.
972     (+) While csh(1) expands, for example,
973           !3d
974     to event 3 with the letter ‘d’ appended to it, tcsh expands it to the
975     last event beginning with ‘3d’; only completely numeric arguments are
976     treated as event numbers.  This makes it possible to recall events begin‐
977     ning with numbers.  To expand
978           !3d
979     as in csh(1) type
980           !{3}d
982   History word designators
983     To select words from an event we can follow the event specification by a
984     ‘:’ and a designator for the desired words.  The words of an input line
985     are numbered from 0, the first (usually command) word being 0, the second
986     word (first argument) being 1, etc.
988     The basic word designators are, with columns for a leading ‘:’ and a
989     leading ‘!’ (for the abbreviated word designators - see History
990     substitution abbreviation):
992           :Word    !Word    History word designator
994           :0                The first (command) word.
996           :n                The nth argument.
998           :^       !^       The first argument, equivalent to ‘:1’.
1000           :$       !$       The last argument.
1002           :%       !%       The word matched by an ?s? search.
1004           :x-y              A range of words.
1006           :-y      !-y      Equivalent to ‘:0-y’.
1008           :*       !*       Equivalent to ‘:^-$’, but returns nothing if the
1009                                 event contains only 1 word.
1011           :x*               Equivalent to ‘:x-$’.
1013           :x-               Equivalent to ‘:x*’, but omitting the last word
1014                                 (‘$’).
1016           :-                Equivalent to ‘:0-’; the command and all argu‐
1017                                 ments except the last argument.
1019     Selected words are inserted into the command line separated by single
1020     blanks.
1022     For example, the ‘diff’ command (event 12) in the history list example in
1023     History event specification,
1024           diff wumpus.man.old wumpus.man
1025     might have been typed as
1026           diff !!:1.old !!:1
1027     (using ‘:1’ to select the first argument from the previous event) or
1028           diff !-2:2 !-2:1
1029     to select and swap the arguments from the ‘cp’ command (event 10).  If we
1030     didn't care about the order of the ‘diff’ we might have typed
1031           diff !-2:1-2
1032     or simply
1033           diff !-2:*
1035     The ‘cp’ command (event 10) might have been typed
1036           cp wumpus.man !#:1.old
1037     using ‘#’ to refer to the current event.
1039     Typing
1040           !n:- hurkle.man
1041     would reuse the first two words from the ‘nroff’ command (event 9) to ex‐
1042     pand to
1043           nroff -man hurkle.man
1045     The ‘:’ separating the event specification from the word designator can
1046     be omitted if the argument selector begins with a ‘^’, ‘$’, ‘%’, ‘-’, or
1047     ‘*’.
1049     For example, our ‘diff’ command (event 12) might have been typed
1050           diff !!^.old !!^
1051     or, equivalently,
1052           diff !!$.old !!$
1053     However, if ‘!!’ is abbreviated ‘!’, an argument selector beginning with
1054     ‘-’ will be interpreted as an event specification.
1056     A history reference may have a word designator but no event specifica‐
1057     tion.  It then references the previous command.
1059     Continuing our ‘diff’ command example (event 12), we could have typed
1060     simply
1061           diff !^.old !^
1062     or, to get the arguments in the opposite order, just
1063           diff !*
1065   History word modifiers
1066     The word or words in a history reference can be edited, or “modified”, by
1067     following it with one or more modifiers (with the leading ‘:’ shown),
1068     each preceded by a ‘:’:
1070           :Word    History word modifier
1072           :h       Remove a trailing pathname component, leaving the head.
1074           :t       Remove all leading pathname components, leaving the tail.
1076           :r       Remove a filename extension ‘.xxx’, leaving the root name.
1078           :e       Remove all but the extension.
1080           :u       Uppercase the first lowercase letter.
1082           :l       Lowercase the first uppercase letter.
1084           :s/l/r/  Substitute l for r.  l is simply a string like r, not a
1085                    regular expression as in the eponymous ed(1) command.  Any
1086                    character may be used as the delimiter in place of ‘/’; a
1087                    ‘\’ can be used to quote the delimiter inside l and r.
1088                    The character ‘&’ in the r is replaced by l; ‘\’ also
1089                    quotes ‘&’.  If l is empty (‘’), the l from a previous
1090                    substitution or the s from a previous search or event num‐
1091                    ber in event specification is used.  The trailing delim‐
1092                    iter may be omitted if it is immediately followed by a
1093                    newline.
1095           :&       Repeat the previous substitution.
1097           :g       Apply the following modifier once to each word.
1099           :a (+)   Apply the following modifier as many times as possible to
1100                    a single word.  ‘:a’ and ‘:g’ can be used together to ap‐
1101                    ply a modifier globally.  With the ‘:s’ modifier, only the
1102                    patterns contained in the original word are substituted,
1103                    not patterns that contain any substitution result.
1105           :p       Print the new command line but do not execute it.
1107           :q       Quote the substituted words, preventing further substitu‐
1108                    tions.
1110           :Q       Same as ‘:q’ but in addition preserve empty variables as a
1111                    string containing a NUL.  This is useful to preserve posi‐
1112                    tional arguments for example:
1113                          > set args=('arg 1' '' 'arg 3')
1114                          > tcsh -f -c 'echo ${#argv}' $args:gQ
1115                          3
1117           :x       Like ‘:q’, but break into words at blanks, tabs and new‐
1118                    lines.
1120     Modifiers are applied to only the first modifiable word (unless ‘:g’ is
1121     used).  It is an error for no word to be modifiable.
1123     For example, the ‘diff’ command (event 12) in the history list example in
1124     History event specification,
1125           diff wumpus.man.old wumpus.man
1126     might have been typed as
1127           diff wumpus.man.old !#^:r
1128     using ‘:r’ to remove ‘.old’ from the first argument on the same line
1129     (‘!#^’).
1131     We could type
1132           echo hello out there
1133     then
1134           echo !*:u
1135     to capitalize ‘hello’,
1136           echo !*:au
1137     to upper case the first word to ‘HELLO’, or
1138           echo !*:agu
1139     to upper case all words.
1141     We might follow
1142           mail -s "I forgot my password" rot
1143     with
1144           !:s/rot/root
1145     to correct the spelling of ‘root’ (see History word modifiers and
1146     Spelling correction (+) for different approaches).
1148     (+) In csh(1) as such, only one modifier may be applied to each history
1149     or variable expansion.  In tcsh, more than one may be used, for example
1151           % mv wumpus.man /usr/share/man/man1/wumpus.1
1152           % man !$:t:r
1153           man wumpus
1155     In csh(1), the result would be
1156           wumpus.1:r
1158     A substitution followed by a ‘:’ may need to be insulated from it with
1159     braces:
1161           > mv a.out /usr/games/wumpus
1162           > setenv PATH !$:h:$PATH
1163           Bad ! modifier: $.
1164           > setenv PATH !{-2$:h}:$PATH
1165           setenv PATH /usr/games:/bin:/usr/bin:.
1167     The first attempt would succeed in csh(1) but fails in tcsh, because tcsh
1168     expects another modifier after the second ‘:’ rather than ‘$’.
1170   History substitution abbreviation
1171     There is a special abbreviation for substitutions; ‘^’, when it is the
1172     first character on an input line, is equivalent to ‘!:s^’.  Thus, we
1173     might follow the example from History word modifiers
1174           mail -s "I forgot my password" rot
1175     with
1176           ^rot^root
1177     to make the spelling correction.  This is the only history substitution
1178     which does not explicitly begin with ‘!’.
1180   History editor commands
1181     Finally, history can be accessed through the editor as well as through
1182     the substitutions just described.  The up-history and down-history,
1183     history-search-backward and history-search-forward, i-search-back and
1184     i-search-fwd, vi-search-back and vi-search-fwd, copy-prev-word and
1185     insert-last-word editor commands search for events in the history list
1186     and copy them into the input buffer.  The toggle-literal-history editor
1187     command switches between the expanded and literal forms of history lines
1188     in the input buffer.  expand-history and expand-line expand history sub‐
1189     stitutions in the current word and in the entire input buffer respec‐
1190     tively.
1192   Alias substitution
1193     The shell maintains a list of aliases which can be set, unset and printed
1194     by the alias and unalias commands.  After a command line is parsed into
1195     simple commands (see Commands) the first word of each command, left-to-
1196     right, is checked to see if it has an alias.  If so, the first word is
1197     replaced by the alias.  If the alias contains a history reference, it un‐
1198     dergoes History substitution as though the original command were the pre‐
1199     vious input line.  If the alias does not contain a history reference, the
1200     argument list is left untouched.
1202     Thus if the alias for ‘ls’ were
1203           ls -l
1204     the command
1205           ls /usr
1206     would become
1207           ls -l /usr
1208     the argument list here being undisturbed.
1210     If the alias for ‘lookup’ were
1211           grep !^ /etc/passwd
1212     then
1213           lookup bill
1214     would become
1215           grep bill /etc/passwd
1217     Aliases can be used to introduce parser metasyntax.  For example,
1218           alias print 'pr \!* | lpr'
1219     defines a “command” (‘print’) which pr(1)s its arguments to the line
1220     printer.
1222     Alias substitution is repeated until the first word of the command has no
1223     alias.  If an alias substitution does not change the first word (as in
1224     the previous example) it is flagged to prevent a loop.  Other loops are
1225     detected and cause an error.
1227     Some aliases are referred to by the shell; see Special aliases (+).
1229   Variable substitution
1230     The shell maintains a list of variables, each of which has as value a
1231     list of zero or more words.  The values of shell variables can be dis‐
1232     played and changed with the set and unset commands.  The system maintains
1233     its own list of “environment” variables.  These can be displayed and
1234     changed with printenv, setenv, and unsetenv.
1236     (+) Variables may be made read-only with
1237           set -r
1238     Read-only variables may not be modified or unset; attempting to do so
1239     will cause an error.  Once made read-only, a variable cannot be made
1240     writable, so
1241           set -r
1242     should be used with caution.  Environment variables cannot be made read-
1243     only.
1245     Some variables are set by the shell or referred to by it.  For instance,
1246     the argv variable is an image of the shell's argument list, and words of
1247     this variable's value are referred to in special ways.  Some of the vari‐
1248     ables referred to by the shell are toggles; the shell does not care what
1249     their value is, only whether they are set or not.  For instance, the
1250     verbose variable is a toggle which causes command input to be echoed.
1251     The -v command line option sets this variable.  Special shell variables
1252     lists all variables which are referred to by the shell.
1254     Other operations treat variables numerically.  The ‘@’ command permits
1255     numeric calculations to be performed and the result assigned to a vari‐
1256     able.  Variable values are, however, always represented as (zero or more)
1257     strings.  For the purposes of numeric operations, the null string is con‐
1258     sidered to be zero, and the second and subsequent words of multi-word
1259     values are ignored.
1261     After the input line is aliased and parsed, and before each command is
1262     executed, variable substitution is performed keyed by ‘$’ characters.
1263     This expansion can be prevented by preceding the ‘$’ with a ‘\’ except
1264     within ‘"’ pairs where it always occurs, and within ‘'’ pairs where it
1265     never occurs.  Strings quoted by ‘`’ are interpreted later (see Command
1266     substitution) so ‘$’ substitution does not occur there until later, if at
1267     all.  A ‘$’ is passed unchanged if followed by a blank, tab, or end-of-
1268     line.
1270     Input/output redirections are recognized before variable expansion, and
1271     are variable expanded separately.  Otherwise, the command name and entire
1272     argument list are expanded together.  It is thus possible for the first
1273     (command) word (to this point) to generate more than one word, the first
1274     of which becomes the command name, and the rest of which become argu‐
1275     ments.
1277     Unless enclosed in ‘"’ or given the ‘:q’ modifier the results of variable
1278     substitution may eventually be command and filename substituted.  Within
1279     ‘"’, a variable whose value consists of multiple words expands to a (por‐
1280     tion of a) single word, with the words of the variable's value separated
1281     by blanks.  When the ‘:q’ modifier is applied to a substitution the vari‐
1282     able will expand to multiple words with each word separated by a blank
1283     and quoted to prevent later command or filename substitution.
1285     The editor command expand-variables, normally bound to ^X-$, can be used
1286     to interactively expand individual variables.
1288   Variable substitution metasequences
1289     The following metasequences are provided for introducing variable values
1290     into the shell input:
1292           $name
1293           ${name}    Substitutes the words of the value of variable name,
1294                      each separated by a blank.  Braces insulate name from
1295                      following characters which would otherwise be part of
1296                      it.  Shell variables have names consisting of letters
1297                      and digits starting with a letter.  The underscore char‐
1298                      acter is considered a letter.  If name is not a shell
1299                      variable, but is set in the environment, then that value
1300                      is returned (but some of the other forms given below are
1301                      not available in this case).
1303           $name[selector]
1304           ${name[selector]}
1305                      Substitutes only the selected words from the value of
1306                      name.  The selector is subjected to ‘$’ substitution and
1307                      may consist of a single number or two numbers separated
1308                      by a ‘-’.  The first word of a variable's value is num‐
1309                      bered ‘1’.  If the first number of a range is omitted it
1310                      defaults to ‘1’.  If the last member of a range is omit‐
1311                      ted it defaults to ‘$#name’.  The selector ‘*’ selects
1312                      all words.  It is not an error for a range to be empty
1313                      if the second argument is omitted or in range.
1315           $0         Substitutes the name of the file from which command in‐
1316                      put is being read.  An error occurs if the name is not
1317                      known.
1319           $number
1320           ${number}  Equivalent to ‘$argv[number]’.
1322           $*         Equivalent to ‘$argv’, which is equivalent to
1323                      ‘$argv[*]’.
1325     Except as noted, it is an error to reference a variable which is not set.
1327     The ‘:’ modifiers described under History word modifiers, except for
1328     ‘:p’, can be applied to the substitutions above.  More than one may be
1329     used.  (+) Braces may be needed to insulate a variable substitution from
1330     a literal ‘:’ just as with History word modifiers; any modifiers must ap‐
1331     pear within the braces.
1333   Variable substitution without modifiers
1334     The following substitutions cannot be modified with ‘:’ modifiers:
1336           $?name
1337           ${?name}    Substitutes the string ‘1’ if name is set, ‘0’ if it is
1338                       not.
1340           $?0         Substitutes ‘1’ if the current input filename is known,
1341                       ‘0’ if it is not.  Always ‘0’ in interactive shells.
1343           $#name
1344           ${#name}    Substitutes the number of words in name.
1346           $#          Equivalent to ‘$#argv’.  (+)
1348           $%name
1349           ${%name}    Substitutes the number of characters in name.  (+)
1351           $%number
1352           ${%number}  Substitutes the number of characters in
1353                       ‘$argv[number]’.  (+)
1355           $?          Equivalent to ‘$status’.  (+)
1357           $$          Substitutes the (decimal) process number of the (par‐
1358                       ent) shell.
1360           $!          Substitutes the (decimal) process number of the last
1361                       background process started by this shell.  (+)
1363           $_          Substitutes the command line of the last command exe‐
1364                       cuted.  (+)
1366           $<          Substitutes a line from the standard input, with no
1367                       further interpretation thereafter.  It can be used to
1368                       read from the keyboard in a shell script.  (+) While
1369                       csh(1) always quotes ‘$<’, as if it were equivalent to
1370                       ‘$<:q’, tcsh does not.  Furthermore, when tcsh is wait‐
1371                       ing for a line to be typed the user may type an inter‐
1372                       rupt to interrupt the sequence into which the line is
1373                       to be substituted, but csh(1) does not allow this.
1375   Command, filename and directory stack substitution
1376     The remaining substitutions are applied selectively to the arguments of
1377     builtin commands.  This means that portions of expressions which are not
1378     evaluated are not subjected to these expansions.  For commands which are
1379     not internal to the shell, the command name is substituted separately
1380     from the argument list.  This occurs very late, after input-output redi‐
1381     rection is performed, and in a child of the main shell.
1383   Command substitution
1384     Command substitution is indicated by a command enclosed in ‘`’.  The out‐
1385     put from such a command is broken into separate words at blanks, tabs and
1386     newlines, and null words are discarded.  The output is variable and com‐
1387     mand substituted and put in place of the original string.
1389     Command substitutions inside double quotes (‘"’) retain blanks and tabs;
1390     only newlines force new words.  The single final newline does not force a
1391     new word in any case.  It is thus possible for a command substitution to
1392     yield only part of a word, even if the command outputs a complete line.
1394     By default, the shell since version 6.12 replaces all newline and car‐
1395     riage return characters in the command by spaces.  If this is switched
1396     off by unsetting csubstnonl, newlines separate commands as usual.
1398   Filename substitution
1399     If a word contains any of the characters ‘*’, ‘?’, ‘[’, or ‘{’ or begins
1400     with the character ‘~’ it is a candidate for filename substitution, also
1401     known as “globbing”.  This word is then regarded as a pattern
1402     (“glob-pattern”), and replaced with an alphabetically sorted list of file
1403     names which match the pattern.
1405     In matching filenames, the character ‘.’ at the beginning of a filename
1406     or immediately following a ‘/’, as well as the character ‘/’ must be
1407     matched explicitly (unless either globdot or globstar or both are set
1408     (+)).  The character ‘*’ matches any string of characters, including the
1409     null string.  The character ‘?’ matches any single character.  The se‐
1410     quence ‘[...]’ matches any one of the characters enclosed.  Within
1411     ‘[...]’, a pair of characters separated by ‘-’ matches any character lex‐
1412     ically between the two.
1414     (+) Some glob-patterns can be negated: The sequence ‘[^...]’ matches any
1415     single character not specified by the characters and/or ranges of charac‐
1416     ters in the braces.
1418     An entire glob-pattern can also be negated with ‘^’:
1420           > echo *
1421           bang crash crunch ouch
1422           > echo ^cr*
1423           bang ouch
1425     Glob-patterns which do not use ‘?’, ‘*’, or ‘[]’, or which use ‘{}’ or
1426     ‘~’ (below) are not negated correctly.
1428     The metanotation ‘a{b,c,d}e’ is a shorthand for ‘abe ace ade’.  Left-to-
1429     right order is preserved:
1430           /usr/source/s1/{oldls,ls}.c
1431     expands to
1432           /usr/source/s1/oldls.c /usr/source/s1/ls.c
1433     The results of matches are sorted separately at a low level to preserve
1434     this order:
1435           ../{memo,*box}
1436     might expand to
1437           ../memo ../box ../mbox
1438     (Note that ‘memo’ was not sorted with the results of matching ‘*box’.)
1439     It is not an error when this construct expands to files which do not ex‐
1440     ist, but it is possible to get an error from a command to which the ex‐
1441     panded list is passed.  This construct may be nested.  As a special case
1442     the words ‘{’, ‘}’, and ‘{}’ are passed undisturbed.
1444     The character ‘~’ at the beginning of a filename refers to home directo‐
1445     ries.  Standing alone, i.e., ‘~’, it expands to the invoker's home direc‐
1446     tory as reflected in the value of the home shell variable.  When followed
1447     by a name consisting of letters, digits and ‘-’ characters the shell
1448     searches for a user with that name and substitutes their home directory;
1449     thus
1450           ~ken
1451     might expand to
1452           /usr/ken
1453     and
1454           ~ken/chmach
1455     might expand to
1456           /usr/ken/chmach
1457     If the character ‘~’ is followed by a character other than a letter or
1458     ‘/’ or appears elsewhere than at the beginning of a word, it is left
1459     undisturbed.  A command like
1460           setenv MANPATH /usr/share/man:/usr/local/share/man:~/lib/man
1461     does not, therefore, do home directory substitution as one might hope.
1463     It is an error for a glob-pattern containing ‘*’, ‘?’, ‘[’, or ‘~’, with
1464     or without ‘^’, not to match any files.  However, only one pattern in a
1465     list of glob-patterns must match a file (so that, e.g.,
1466           rm *.a *.c *.o
1467     would fail only if there were no files in the current directory ending in
1468     ‘.a’, ‘.c’, or ‘.o’), and if the nonomatch shell variable is set a pat‐
1469     tern (or list of patterns) which matches nothing is left unchanged rather
1470     than causing an error.
1472     The globstar shell variable can be set to allow ‘**’ or ‘***’ as a file
1473     glob pattern that matches any string of characters including ‘/’, recur‐
1474     sively traversing any existing sub-directories.  For example,
1475           ls **.c
1476     will list all the .c files in the current directory tree.  If used by it‐
1477     self, it will match zero or more sub-directories.  For example
1478           ls /usr/include/**/time.h
1479     will list any file named ‘time.h’ in the /usr/include directory tree;
1480           ls /usr/include/**time.h
1481     will match any file in the /usr/include directory tree ending in
1482     ‘time.h’; and
1483           ls /usr/include/**time**.h
1484     will match any .h file with ‘time’ either in a subdirectory name or in
1485     the filename itself.  To prevent problems with recursion, the ‘**’ glob-
1486     pattern will not descend into a symbolic link containing a directory.  To
1487     override this, use ‘***’ (+)
1489     The noglob shell variable can be set to prevent filename substitution,
1490     and the expand-glob editor command, normally bound to ^X-*, can be used
1491     to interactively expand individual filename substitutions.
1493   Directory stack substitution (+)
1494     The directory stack is a list of directories, numbered from zero, used by
1495     the pushd, popd, and dirs builtin commands.  dirs can print, store in a
1496     file, restore and clear the directory stack at any time, and the savedirs
1497     and dirsfile shell variables can be set to store the directory stack au‐
1498     tomatically on logout and restore it on login.  The dirstack shell vari‐
1499     able can be examined to see the directory stack and set to put arbitrary
1500     directories into the directory stack.
1502     The character ‘=’ followed by one or more digits expands to an entry in
1503     the directory stack.  The special case ‘=-’ expands to the last directory
1504     in the stack.  For example,
1506           > dirs -v
1507           0       /usr/bin
1508           1       /usr/spool/uucp
1509           2       /usr/accts/sys
1510           > echo =1
1511           /usr/spool/uucp
1512           > echo =0/calendar
1513           /usr/bin/calendar
1514           > echo =-
1515           /usr/accts/sys
1517     The noglob and nonomatch shell variables and the expand-glob editor com‐
1518     mand apply to directory stack as well as filename substitutions.
1520   Other substitutions (+)
1521     There are several more transformations involving filenames, not strictly
1522     related to the above but mentioned here for completeness.  Any filename
1523     may be expanded to a full path when the symlinks variable is set to
1524     ‘expand’.  Quoting prevents this expansion, and the normalize-path editor
1525     command does it on demand.  The normalize-command editor command expands
1526     commands in PATH into full paths on demand.  Finally, cd and pushd inter‐
1527     pret ‘-’ as the old working directory (equivalent to the shell variable
1528     owd).  This is not a substitution at all, but an abbreviation recognized
1529     by only those commands.  Nonetheless, it too can be prevented by quoting.
1531   Commands
1532     The next three sections describe how the shell executes commands and
1533     deals with their input and output.
1535   Simple commands, pipelines and sequences
1536     A simple command is a sequence of words, the first of which specifies the
1537     command to be executed.  A series of simple commands joined by ‘|’ char‐
1538     acters forms a pipeline.  The output of each command in a pipeline is
1539     connected to the input of the next.
1541     Simple commands and pipelines may be joined into sequences with ‘;’, and
1542     will be executed sequentially.  Commands and pipelines can also be joined
1543     into sequences with ‘||’ or ‘&&’, indicating, as in the C language, that
1544     the second is to be executed only if the first fails or succeeds respec‐
1545     tively.
1547     A simple command, pipeline or sequence may be placed in parentheses (‘(’
1548     and ‘)’) to form a simple command, which may in turn be a component of a
1549     pipeline or sequence.  A command, pipeline or sequence can be executed
1550     without waiting for it to terminate by following it with an ‘&’.
1552   Builtin and non-builtin command execution
1553     Builtin commands are executed within the shell.  If any component of a
1554     pipeline except the last is a builtin command, the pipeline is executed
1555     in a subshell.
1557     Parenthesized commands are always executed in a subshell.
1559           (cd; pwd); pwd
1561     thus prints the home directory, leaving you where you were (printing this
1562     after the home directory), while
1564           cd; pwd
1566     leaves you in the home directory.  Parenthesized commands are most often
1567     used to prevent cd from affecting the current shell.
1569     When a command to be executed is found not to be a builtin command the
1570     shell attempts to execute the command via execve(2).  Each word in the
1571     variable path names a directory in which the shell will look for the com‐
1572     mand.  If the shell is not given a -f option, the shell hashes the names
1573     in these directories into an internal table so that it will try an
1574     execve(2) in only a directory where there is a possibility that the com‐
1575     mand resides there.  This greatly speeds command location when a large
1576     number of directories are present in the search path.  This hashing mech‐
1577     anism is not used:
1579           1.   If hashing is turned explicitly off via unhash.
1581           2.   If the shell was given a -f argument.
1583           3.   For each directory component of path which does not begin with
1584                a ‘/’.
1586           4.   If the command contains a ‘/’.
1588     In the above four cases the shell concatenates each component of the path
1589     vector with the given command name to form a path name of a file which it
1590     then attempts to execute it.  If execution is successful, the search
1591     stops.
1593     If the file has execute permissions but is not an executable to the sys‐
1594     tem (i.e., it is neither an executable binary nor a script that specifies
1595     its interpreter), then it is assumed to be a file containing shell com‐
1596     mands and a new shell is spawned to read it.  The shell special alias may
1597     be set to specify an interpreter other than the shell itself.
1599     On systems which do not understand the ‘#!’ script interpreter convention
1600     the shell may be compiled to emulate it; see the version shell variable.
1601     If so, the shell checks the first line of the file to see if it is of the
1602     form
1603           #!interpreter arg ...
1604     If it is, the shell starts interpreter with the given args and feeds the
1605     file to it on standard input.
1607   Input/output
1608     The standard input and standard output of a command may be redirected
1609     with the following syntax:
1611           < name   Open file name (which is first variable, command and file‐
1612                    name expanded) as the standard input.
1614           << word  Read the shell input up to a line which is identical to
1615                    word.  word is not subjected to variable, filename or com‐
1616                    mand substitution, and each input line is compared to word
1617                    before any substitutions are done on this input line.  Un‐
1618                    less a quoting ‘\’, ‘"’, ‘'’, or ‘`’ appears in word vari‐
1619                    able and command substitution is performed on the inter‐
1620                    vening lines, allowing ‘\’ to quote ‘$’, ‘\’, and ‘`’.
1621                    Commands which are substituted have all blanks, tabs, and
1622                    newlines preserved, except for the final newline which is
1623                    dropped.  The resultant text is placed in an anonymous
1624                    temporary file which is given to the command as standard
1625                    input.
1627           > name
1628           >! name
1629           >& name
1630           >&! name
1631                    The file name is used as standard output.  If the file
1632                    does not exist then it is created; if the file exists, it
1633                    is truncated, its previous contents being lost.
1635                    If the shell variable noclobber is set, then the file must
1636                    not exist or be a character special file (e.g., a terminal
1637                    or /dev/null) or an error results.  This helps prevent ac‐
1638                    cidental destruction of files.  In this case the ‘!’ forms
1639                    can be used to suppress this check.  If ‘notempty’ is
1640                    given in noclobber, ‘>’ is allowed on empty files; if
1641                    ‘ask’ is given in noclobber, an interacive confirmation is
1642                    presented, rather than an error.
1644                    The forms involving ‘&’ route the diagnostic output into
1645                    the specified file as well as the standard output.  name
1646                    is expanded in the same way as ‘<’ input filenames are.
1648           >> name
1649           >>& name
1650           >>! name
1651           >>&! name
1652                    Like ‘>’, but appends output to the end of name.  If the
1653                    shell variable noclobber is set, then it is an error for
1654                    the file not to exist, unless one of the ‘!’ forms is
1655                    given.
1657     A command receives the environment in which the shell was invoked as mod‐
1658     ified by the input-output parameters and the presence of the command in a
1659     pipeline.  Thus, unlike some previous shells, commands run from a file of
1660     shell commands have no access to the text of the commands by default;
1661     rather they receive the original standard input of the shell.  The ‘<<’
1662     mechanism should be used to present inline data.  This permits shell com‐
1663     mand scripts to function as components of pipelines and allows the shell
1664     to block read its input.  Note that the default standard input for a com‐
1665     mand run detached is not the empty file /dev/null, but the original stan‐
1666     dard input of the shell.  If this is a terminal and if the process at‐
1667     tempts to read from the terminal, then the process will block and the
1668     user will be notified (see Jobs).
1670     Diagnostic output may be directed through a pipe with the standard out‐
1671     put.  Simply use the form ‘|&’ rather than just ‘|’.
1673     The shell cannot presently redirect diagnostic output without also redi‐
1674     recting standard output, but
1675           ( command > output-file ) >& error-file
1676     is often an acceptable workaround.  Either output-file or error-file may
1677     be /dev/tty to send output to the terminal.
1679   Features
1680     Having described how the shell accepts, parses and executes command
1681     lines, we now turn to a variety of its useful features.
1683   Control flow
1684     The shell contains a number of commands which can be used to regulate the
1685     flow of control in command files (shell scripts) and (in limited but use‐
1686     ful ways) from terminal input.  These commands all operate by forcing the
1687     shell to reread or skip in its input and, due to the implementation, re‐
1688     strict the placement of some of the commands.
1690     The foreach, switch, and while statements, as well as the if ... then ...
1691     else form of the if statement, require that the major keywords appear in
1692     a single simple command on an input line as shown below.
1694     If the shell's input is not seekable, the shell buffers up input whenever
1695     a loop is being read and performs seeks in this internal buffer to accom‐
1696     plish the rereading implied by the loop.  (To the extent that this al‐
1697     lows, backward gotos will succeed on non-seekable inputs.)
1699   Expressions
1700     The if, while, and exit builtin commands use expressions with a common
1701     syntax.  The expressions can include any of the operators described in
1702     the next three sections.  Note that the @ builtin command has its own
1703     separate syntax.
1705   Logical, arithmetical and comparison operators
1706     These operators are similar to those of C and have the same precedence.
1708     The operators, in descending precedence, with equivalent precedence per
1709     line, are:
1711           (     )
1712           ~
1713           !
1714           *     /     %
1715           +     -
1716           <<    >>
1717           <=    >=    <     >
1718           ==    !=    =~    !~
1719           &
1720           ^
1721           |
1722           &&
1723           ||
1725     The ‘==’ ‘!=’ ‘=~’ and ‘!~’ operators compare their arguments as strings;
1726     all others operate on numbers.  The operators ‘=~’ and ‘!~’ are like ‘==’
1727     and ‘!=’ except that the right hand side is a glob-pattern (see Filename
1728     substitution) against which the left hand operand is matched.  This re‐
1729     duces the need for use of the switch builtin command in shell scripts
1730     when all that is really needed is pattern matching.
1732     Null or missing arguments are considered ‘0’.  The results of all expres‐
1733     sions are strings, which represent decimal numbers.  It is important to
1734     note that no two components of an expression can appear in the same word;
1735     except when adjacent to components of expressions which are syntactically
1736     significant to the parser (‘&’, ‘|’, ‘<’, ‘>’, ‘(’, ‘)’) they should be
1737     surrounded by spaces.
1739   Command exit status
1740     Commands can be executed in expressions and their exit status returned by
1741     enclosing them in braces (‘{’ and ‘}’).  Remember that the braces should
1742     be separated from the words of the command by spaces.  Command executions
1743     succeed, returning true, i.e., ‘1’, if the command exits with status 0,
1744     otherwise they fail, returning false, i.e., ‘0’.  If more detailed status
1745     information is required then the command should be executed outside of an
1746     expression and the status shell variable examined.
1748   File inquiry operators
1749     Some of these operators perform true/false tests on files and related ob‐
1750     jects.  They are of the form -op file, where -op is one of:
1752           -op      True/false file inquiry operator
1754           -r       Read access.
1755           -w       Write access.
1756           -x       Execute access.
1757           -X       Executable in the path or shell builtin, e.g., ‘-X ls’ and
1758                    ‘-X ls-F’ are generally true, but ‘-X /bin/ls’ is not. (+)
1759           -e       Existence.
1760           -o       Ownership.
1761           -z       Zero size.
1762           -s       Non-zero size. (+)
1763           -f       Plain file.
1764           -d       Directory.
1765           -l       Symbolic link. (+) *
1766           -b       Block special file. (+)
1767           -c       Character special file. (+)
1768           -p       Named pipe (fifo). (+) *
1769           -S       Socket special file. (+) *
1770           -u       Set-user-ID bit is set. (+)
1771           -g       Set-group-ID bit is set. (+)
1772           -k       Sticky bit is set. (+)
1773           -t       file (which must be a digit) is an open file descriptor
1774                    for a terminal device. (+)
1775           -R       Has been migrated (Convex only). (+)
1776           -L       Applies subsequent operators in a multiple-operator test
1777                    to a symbolic link rather than to the file to which the
1778                    link points. (+) *
1780     file is command and filename expanded and then tested to see if it has
1781     the specified relationship to the real user.  If file does not exist or
1782     is inaccessible or, for the operators indicated by ‘*’, if the specified
1783     file type does not exist on the current system, then all inquiries return
1784     false, i.e., ‘0’.
1786     These operators may be combined for conciseness:
1787           -xy file
1788     is equivalent to
1789           -x file && -y file
1790     (+) For example, ‘-fx’ is true (returns ‘1’) for plain executable files,
1791     but not for directories.
1793     -L may be used in a multiple-operator test to apply subsequent operators
1794     to a symbolic link rather than to the file to which the link points.  For
1795     example, -lLo is true for links owned by the invoking user.  -Lr, -Lw,
1796     and -Lx are always true for links and false for non-links.  -L has a dif‐
1797     ferent meaning when it is the last operator in a multiple-operator test;
1798     see below.
1800     It is possible but not useful, and sometimes misleading, to combine oper‐
1801     ators which expect file to be a file with operators which do not (e.g.,
1802     -X and -t).  Following -L with a non-file operator can lead to particu‐
1803     larly strange results.
1805     Other operators return other information, i.e., not just ‘0’ or ‘1’.  (+)
1806     They have the same format as before; -op may be one of:
1808           -op      Extended file inquiry operator
1810           -A       Last file access time, as the number of seconds since the
1811                    epoch.
1812           -A:      Like ‘A’, but in timestamp format, e.g., ‘Fri May 14
1813                    16:36:10 1993’.
1814           -M       Last file modification time.
1815           -M:      Like -M, but in timestamp format.
1816           -C       Last inode modification time.
1817           -C:      Like -C, but in timestamp format.
1818           -D       Device number.
1819           -I       Inode number.
1820           -F       Composite -file identifier, in the form device:inode.
1821           -L       The name of the file pointed to by a symbolic link.
1822           -N       Number of (hard) links.
1823           -P       Permissions, in octal, without leading zero.
1824           -P:      Like -P, with leading zero.
1825           -Pmode   Equivalent to
1826                          -P file & mode
1827                    For example, ‘-P22 file’ returns ‘22’ if file is writable
1828                    by group and other, ‘20’ if by group only, and ‘0’ if by
1829                    neither.
1830           -Pmode:  Like -Pmode, with leading zero.
1831           -U       Numeric userid.
1832           -U:      Username, or the numeric userid if the username is un‐
1833                    known.
1834           -G       Numeric groupid.
1835           -G:      Groupname, or the numeric groupid if the groupname is un‐
1836                    known.
1837           -Z       Size, in bytes.
1839     Only one of these operators may appear in a multiple-operator test, and
1840     it must be the last.  Note that ‘L’ has a different meaning at the end of
1841     and elsewhere in a multiple-operator test.  Because ‘0’ is a valid return
1842     value for many of these operators, they do not return ‘0’ when they fail:
1843     most return ‘-1’, and ‘F’ returns ‘:’.
1845     If the shell is compiled with POSIX defined (see the version shell vari‐
1846     able), the result of a file inquiry is based on the permission bits of
1847     the file and not on the result of the access(2) system call.  For exam‐
1848     ple, if one tests a file with -w whose permissions would ordinarily allow
1849     writing but which is on a file system mounted read-only, the test will
1850     succeed in a POSIX shell but fail in a non-POSIX shell.
1852     File inquiry operators can also be evaluated with the filetest builtin
1853     command (+).
1855   Jobs
1856     The shell associates a job with each pipeline.  It keeps a table of cur‐
1857     rent jobs, printed by the jobs command, and assigns them small integer
1858     numbers.  When a job is started asynchronously with ‘&’, the shell prints
1859     a line which looks like
1861           [1] 1234
1863     indicating that the job which was started asynchronously was job number 1
1864     and had one (top-level) process, whose process id was 1234.
1866     If you are running a job and wish to do something else you may hit the
1867     suspend key (usually ^Z), which sends a STOP signal to the current job.
1868     The shell will then normally indicate that the job has been
1869           Suspended
1870     and print another prompt.  If the listjobs shell variable is set, all
1871     jobs will be listed like the jobs builtin command; if it is set to ‘long’
1872     the listing will be in long format, like ‘jobs -l’.  You can then manipu‐
1873     late the state of the suspended job.  You can put it in the “background”
1874     with the bg command or run some other commands and eventually bring the
1875     job back into the “foreground” with fg.  (See also the run-fg-editor edi‐
1876     tor command.)  A ^Z takes effect immediately and is like an interrupt in
1877     that pending output and unread input are discarded when it is typed.  The
1878     wait builtin command causes the shell to wait for all background jobs to
1879     complete.
1881     The ^] key sends a delayed suspend signal, which does not generate a STOP
1882     signal until a program attempts to read(2) it, to the current job.  This
1883     can usefully be typed ahead when you have prepared some commands for a
1884     job which you wish to stop after it has read them.  The ^Y key performs
1885     this function in csh(1); in tcsh, ^Y is an editing command.  (+)
1887     A job being run in the background stops if it tries to read from the ter‐
1888     minal.  Background jobs are normally allowed to produce output, but this
1889     can be disabled by giving the command
1890           stty tostop
1891     If you set this tty option, then background jobs will stop when they try
1892     to produce output like they do when they try to read input.
1894     There are several ways to refer to jobs in the shell.  The character ‘%’
1895     introduces a job name.  If you wish to refer to job number 1, you can
1896     name it as
1897           %1
1898     Just naming a job brings it to the foreground; thus
1899           %1
1900     is a synonym for
1901           fg %1
1902     bringing job 1 back into the foreground.  Similarly, typing
1903           %1 &
1904     resumes job 1 in the background, just like
1905           bg %1
1906     A job can also be named by an unambiguous prefix of the string typed in
1907     to start it:
1908           %ex
1909     would normally restart a suspended ex(1) job, if there were only one sus‐
1910     pended job whose name began with the string ‘ex’.  It is also possible to
1911     type
1912           %?string
1913     to specify a job whose text contains string, if there is only one such
1914     job.
1916     The shell maintains a notion of the current and previous jobs.  In output
1917     pertaining to jobs, the current job is marked with a ‘+’ and the previous
1918     job with a ‘-’.  The abbreviations ‘%+’, ‘%’, and (by analogy with the
1919     syntax of the history mechanism) ‘%%’ all refer to the current job, and
1920     ‘%-’ refers to the previous job.
1922     The job control mechanism requires that the stty(1) option ‘new’ be set
1923     on some systems.  It is an artifact from a “new” implementation of the
1924     tty driver which allows generation of interrupt characters from the key‐
1925     board to tell jobs to stop.  See stty(1) and the setty builtin command
1926     for details on setting options in the new tty driver.
1928   Status reporting
1929     The shell learns immediately whenever a process changes state.  It nor‐
1930     mally informs you whenever a job becomes blocked so that no further
1931     progress is possible, but only right before it prints a prompt.  This is
1932     done so that it does not otherwise disturb your work.  If, however, you
1933     set the shell variable notify, the shell will notify you immediately of
1934     changes of status in background jobs.  There is also a builtin command
1935     notify which marks a single process so that its status changes will be
1936     immediately reported.  By default notify marks the current process; sim‐
1937     ply enter
1938           notify
1939     after starting a background job to mark it for immediate status report‐
1940     ing.
1942     When you try to leave the shell while jobs are stopped, you will be
1943     warned that
1944           There are suspended jobs.
1946     You may use the jobs command to see what they are.  If you do this or im‐
1947     mediately try to exit again, the shell will not warn you a second time,
1948     and the suspended jobs will be terminated.
1950   Automatic, periodic and timed events (+)
1951     There are various ways to run commands and take other actions automati‐
1952     cally at various times in the “life cycle” of the shell.  They are summa‐
1953     rized here, and described in detail under the appropriate Builtin
1954     commands, Special shell variables, and Special aliases (+).
1956     The sched builtin command puts commands in a scheduled-event list, to be
1957     executed by the shell at a given time.
1959     The beepcmd, cwdcmd, jobcmd, periodic, precmd, and postcmd Special
1960     aliases (+) can be set, respectively, to execute commands: when the shell
1961     wants to ring the bell, when the working directory changes, when a job is
1962     started or is brought into the foreground, every tperiod minutes, before
1963     each prompt, and before each command gets executed.
1965     The autologout shell variable can be set to log out or lock the shell af‐
1966     ter a given number of minutes of inactivity.
1968     The mail shell variable can be set to check for new mail periodically.
1970     The printexitvalue shell variable can be set to print the exit status of
1971     commands which exit with a status other than zero.
1973     The rmstar shell variable can be set to ask the user, when
1974           rm *
1975     is typed, if that is really what was meant.
1977     The time shell variable can be set to execute the time builtin command
1978     after the completion of any process that takes more than a given number
1979     of CPU seconds.
1981     The watch and who shell variables can be set to report when selected
1982     users log in or out, and the log builtin command reports on those users
1983     at any time.
1985   Native Language System support (+)
1986     The shell is eight bit clean (if so compiled; see the version shell vari‐
1987     able) and thus supports character sets needing this capability.  NLS sup‐
1988     port differs depending on whether or not the shell was compiled to use
1989     the system's NLS (again, see version).  In either case, 7-bit ASCII is
1990     the default character code (e.g., the classification of which characters
1991     are printable) and sorting, and changing the LANG or LC_CTYPE environment
1992     variables causes a check for possible changes in these respects.
1994     When using the system's NLS, the setlocale(3) function is called to de‐
1995     termine appropriate character code/classification and sorting (e.g.,
1996     ‘en_CA.UTF-8’ would yield ‘UTF-8’ as the character code).  This function
1997     typically examines the LANG and LC_CTYPE environment variables; refer to
1998     the system documentation for further details.  When not using the sys‐
1999     tem's NLS, the shell simulates it by assuming that the ISO 8859-1 charac‐
2000     ter set is used whenever either of the LANG and LC_CTYPE variables are
2001     set, regardless of their values.  Sorting is not affected for the simu‐
2002     lated NLS.
2004     In addition, with both real and simulated NLS, all printable characters
2005     in the range \200-\377, i.e., those that have M-char bindings, are auto‐
2006     matically rebound to self-insert-command.  The corresponding binding for
2007     the escape-char sequence, if any, is left alone.  These characters are
2008     not rebound if the NOREBIND environment variable is set.  This may be
2009     useful for the simulated NLS or a primitive real NLS which assumes full
2010     ISO 8859-1.  Otherwise, all M-char bindings in the range \240-\377 are
2011     effectively undone.  Explicitly rebinding the relevant keys with bindkey
2012     is of course still possible.
2014     Unknown characters (i.e., those that are neither printable nor control
2015     characters) are printed in the format \nnn.  If the tty is not in 8 bit
2016     mode, other 8 bit characters are printed by converting them to ASCII and
2017     using standout mode.  The shell never changes the 7/8 bit mode of the tty
2018     and tracks user-initiated changes of 7/8 bit mode.  NLS users (or, for
2019     that matter, those who want to use a meta key) may need to explicitly set
2020     the tty in 8 bit mode through the appropriate stty(1) command in, e.g.,
2021     the ~/.login file.
2023   OS variant support (+)
2024     A number of new builtin commands are provided to support features in par‐
2025     ticular operating systems.  All are described in detail in the Builtin
2026     commands section.
2028     On systems that support TCF (aix-ibm370, aix-ps2), getspath and setspath
2029     get and set the system execution path, getxvers and setxvers get and set
2030     the experimental version prefix and migrate migrates processes between
2031     sites.  The jobs builtin prints the site on which each job is executing.
2033     Under BS2000, bs2cmd executes commands of the underlying BS2000/OSD oper‐
2034     ating system.
2036     Under Domain/OS, inlib adds shared libraries to the current environment,
2037     rootnode changes the rootnode and ver changes the systype.
2039     Under Mach, setpath is equivalent to Mach's setpath(1).
2041     Under Masscomp/RTU and Harris CX/UX, universe sets the universe.
2043     Under Harris CX/UX, ucb or att runs a command under the specified uni‐
2044     verse.
2046     Under Convex/OS, warp prints or sets the universe.
2048     The VENDOR, OSTYPE, and MACHTYPE environment variables indicate respec‐
2049     tively the vendor, operating system and machine type (microprocessor
2050     class or machine model) of the system on which the shell thinks it is
2051     running.  These are particularly useful when sharing one's home directory
2052     between several types of machines; one can, for example,
2054           set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)
2056     in one's ~/.login and put executables compiled for each machine in the
2057     appropriate directory.
2059     The version shell variable indicates what options were chosen when the
2060     shell was compiled.
2062     Note also the newgrp builtin, the afsuser and echo_style shell variables
2063     and the system-dependent locations of the shell's input files (see
2064     FILES).
2066   Signal handling
2067     Login shells ignore interrupts when reading the file ~/.logout.  The
2068     shell ignores quit signals unless started with -q.  Login shells catch
2069     the terminate signal, but non-login shells inherit the terminate behavior
2070     from their parents.  Other signals have the values which the shell inher‐
2071     ited from its parent.
2073     In shell scripts, the shell's handling of interrupt and terminate signals
2074     can be controlled with onintr, and its handling of hangups can be con‐
2075     trolled with hup and nohup.
2077     The shell exits on a hangup (see also the logout shell variable).  By de‐
2078     fault, the shell's children do too, but the shell does not send them a
2079     hangup when it exits.  hup arranges for the shell to send a hangup to a
2080     child when it exits, and nohup sets a child to ignore hangups.
2082   Terminal management (+)
2083     The shell uses three different sets of terminal (“tty”) modes: ‘edit’,
2084     used when editing; ‘quote’, used when quoting literal characters; and
2085     ‘execute’, used when executing commands.  The shell holds some settings
2086     in each mode constant, so commands which leave the tty in a confused
2087     state do not interfere with the shell.  The shell also matches changes in
2088     the speed and padding of the tty.  The list of tty modes that are kept
2089     constant can be examined and modified with the setty builtin.  Note that
2090     although the editor uses CBREAK mode (or its equivalent), it takes typed-
2091     ahead characters anyway.
2093     The echotc, settc, and telltc commands can be used to manipulate and de‐
2094     bug terminal capabilities from the command line.
2096     On systems that support SIGWINCH or SIGWINDOW, the shell adapts to window
2097     resizing automatically and adjusts the environment variables LINES and
2098     COLUMNS if set.  If the environment variable TERMCAP contains ‘li#’ and
2099     ‘co#’ fields, the shell adjusts them to reflect the new window size.


2102     The next sections of this manual describe all of the available Builtin
2103     commands, Special aliases (+), and Special shell variables.
2105   Builtin commands
2106     %job    A synonym for the fg builtin command.
2108     %job &  A synonym for the bg builtin command.
2110     :       Does nothing, successfully.
2112     @
2113     @ name = expr
2114     @ name[index] = expr
2115     @ name++|--
2116     @ name[index]++|--
2117             The first form prints the values of all shell variables.
2119             The second form assigns the value of expr to name.
2121             The third form assigns the value of expr to the index'th compo‐
2122             nent of name; both name and its index'th component must already
2123             exist.
2125             expr may contain the operators ‘*’, ‘+’, etc., as in C.  If expr
2126             contains ‘<’, ‘>’, ‘&’, or ‘|’ then at least that part of expr
2127             must be placed within (‘’ and ‘’).  Note that the syntax of expr
2128             has nothing to do with that described under Expressions.
2130             The fourth and fifth forms increment (‘++’) or decrement (‘--’)
2131             name or its index'th component.
2133             The space between ‘@’ and name is required.  The spaces between
2134             name and ‘=’ and between ‘=’ and expr are optional.  Components
2135             of expr must be separated by spaces.
2137     alias [name [wordlist]]
2138             Without arguments, prints all aliases.
2140             With name, prints the alias for name.
2142             With name and wordlist, assigns wordlist as the alias of name.
2143             wordlist is command and filename substituted.
2145             name may not be ‘alias’ or ‘unalias’.  See also the unalias
2146             builtin command.
2148     alloc   Shows the amount of dynamic memory acquired, broken down into
2149             used and free memory.  With an argument shows the number of free
2150             and used blocks in each size category.  The categories start at
2151             size 8 and double at each step.  This command's output may vary
2152             across system types, because systems other than the VAX may use a
2153             different memory allocator.
2155     bg [%job ...]
2156             Puts the specified jobs (or, without arguments, the current job)
2157             into the background, continuing each if it is stopped.  job may
2158             be a number, a string, ‘’, ‘%’, ‘+’, or ‘-’ as described under
2159             Jobs.
2161     bindkey [-l|-d|-e|-v|-u] (+)
2162     bindkey [-a] [-b] [-k] [-r] [--] key (+)
2163     bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
2164             The first form either lists all bound keys and the editor command
2165             to which each is bound, lists a description of the commands, or
2166             binds all keys to a specific mode.
2168             The second form lists the editor command to which key is bound.
2170             The third form binds the editor command command to key.
2172             Supported bindkey options:
2174             Option  bindkey description
2176             -a      Lists or changes key-bindings in the alternative key map.
2177                     This is the key map used in vimode command mode.
2179             -b      key is interpreted as a control character written
2180                     ^character (e.g., ^A) or C-character (e.g., C-A), a meta
2181                     character written M-character (e.g., M-A), a function key
2182                     written F-string (e.g., F-string), or an extended prefix
2183                     key written X-character (e.g., X-A).
2185             -c      command is interpreted as a builtin or external command
2186                     instead of an editor command.
2188             -d      Binds all keys to the standard bindings for the default
2189                     editor, as per -e and -v.
2191             -e      Binds all keys to emacs(1)-style bindings.  Unsets
2192                     vimode.
2194             -k      key is interpreted as a symbolic arrow key name, which
2195                     may be one of ‘down’, ‘up’, ‘left’, or ‘right’.
2197             -l      Lists all editor commands and a short description of
2198                     each.
2200             -r      Removes key's binding.  Be careful: ‘bindkey -r’ does not
2201                     bind key to self-insert-command, it unbinds key com‐
2202                     pletely.
2204             -s      command is taken as a literal string and treated as ter‐
2205                     minal input when key is typed.  Bound keys in command are
2206                     themselves reinterpreted, and this continues for ten lev‐
2207                     els of interpretation.
2209             -u (or any invalid option)
2210                     Prints a usage message.
2212             -v      Binds all keys to vi(1)-style bindings.  Sets vimode.
2214             --      Forces a break from option processing, so the next word
2215                     is taken as key even if it begins with ‘-’.
2217             key may be a single character or a string.  If a command is bound
2218             to a string, the first character of the string is bound to
2219             sequence-lead-in and the entire string is bound to the command.
2221             Control characters in key can be literal (they can be typed by
2222             preceding them with the editor command quoted-insert, normally
2223             bound to ^V) or written caret-character style, e.g., ^A.  Delete
2224             is written ^? (caret-question mark).  key and command can contain
2225             backslashed escape sequences (in the style of System V echo(1))
2226             as follows:
2228             Escape  Description
2230             \a      Bell.
2232             \b      Backspace.
2234             \e      Escape.
2236             \f      Form feed.
2238             \n      Newline.
2240             \r      Carriage return.
2242             \t      Horizontal tab.
2244             \v      Vertical tab.
2246             \nnn    The ASCII character corresponding to the octal number
2247                     nnn.
2249             ‘\’ nullifies the special meaning of the following character, if
2250             it has any, notably ‘\’ and ‘^’.
2252     bs2cmd bs2000-command (+)
2253             Passes bs2000-command to the BS2000 command interpreter for exe‐
2254             cution.  Only non-interactive commands can be executed, and it is
2255             not possible to execute any command that would overlay the image
2256             of the current process, like /EXECUTE or /CALL-PROCEDURE. (BS2000
2257             only)
2259     break   Causes execution to resume after the end of the nearest enclosing
2260             foreach or while.  The remaining commands on the current line are
2261             executed.  Multi-level breaks are thus possible by writing them
2262             all on one line.
2264     breaksw
2265             Causes a break from a switch, resuming after the endsw.
2267     builtins (+)
2268             Prints the names of all builtin commands.
2270     bye (+)
2271             A synonym for the logout builtin command.  Available only if the
2272             shell was so compiled; see the version shell variable.
2274     case label:
2275             A label in a switch statement as discussed below.
2277     cd [-p] [-l] [-n|-v] [--] [name]
2278             If a directory name is given, changes the shell's working direc‐
2279             tory to name.  If not, changes to home, unless the cdtohome vari‐
2280             able is not set, in which case a name is required.  If name is
2281             ‘-’ it is interpreted as the previous working directory (see
2282             Other substitutions (+)).  (+) If name is not a subdirectory of
2283             the current directory (and does not begin with ‘/’, ‘./’ or
2284             ‘../’), each component of the variable cdpath is checked to see
2285             if it has a subdirectory name.  Finally, if all else fails but
2286             name is a shell variable whose value begins with ‘/’ or ‘.’, then
2287             this is tried to see if it is a directory, and the -p option is
2288             implied.
2290             With -p, prints the final directory stack, just like dirs.  The
2291             -l, -n, and -v flags have the same effect on cd as on dirs, and
2292             they imply -p (+).  Using -- forces a break from option process‐
2293             ing so the next word is taken as the directory name even if it
2294             begins with ‘-’ (+).
2296             See also the implicitcd and cdtohome shell variables.
2298     chdir   A synonym for the cd builtin command.
2300     complete [command [word/pattern/list[:select]/[[suffix]/] ...]]  (+)
2301             Without arguments, lists all completions.
2303             With command, lists completions for command.
2305             With command and word ..., defines completions.
2307             command may be a full command name or a glob-pattern (see
2308             Filename substitution).  It can begin with ‘-’ to indicate that
2309             completion should be used only when command is ambiguous.
2311             word specifies which word relative to the current word is to be
2312             completed, and may be one of the following:
2314                   word   Completion word
2316                   c      Current-word completion.  pattern is a glob-pattern
2317                          which must match the beginning of the current word
2318                          on the command line.  pattern is ignored when com‐
2319                          pleting the current word.
2321                   C      Like ‘c’, but includes pattern when completing the
2322                          current word.
2324                   n      Next-word completion.  pattern is a glob-pattern
2325                          which must match the beginning of the previous word
2326                          on the command line.
2328                   N      Like ‘n’, but must match the beginning of the word
2329                          two before the current word.
2331                   p      Position-dependent completion.  pattern is a numeric
2332                          range, with the same syntax used to index shell
2333                          variables, which must include the current word.
2335             list, the list of possible completions, may be one of the follow‐
2336             ing:
2338                   list   Completion item
2340                   a      Aliases.
2342                   b      Bindings (editor commands).
2344                   c      Commands (builtin or external commands).
2346                   C      External commands which begin with the supplied path
2347                          prefix.
2349                   d      Directories.
2351                   D      Directories which begin with the supplied path pre‐
2352                          fix.
2354                   e      Environment variables.
2356                   f      Filenames.
2358                   F      Filenames which begin with the supplied path prefix.
2360                   g      Groupnames.
2362                   j      Jobs.
2364                   l      Limits.
2366                   n      Nothing.
2368                   s      Shell variables.
2370                   S      Signals.
2372                   t      Plain (“text”) files.
2374                   T      Plain (“text”) files which begin with the supplied
2375                          path prefix.
2377                   v      Any variables.
2379                   u      Usernames.
2381                   x      Like ‘n’, but prints select when list-choices is
2382                          used.
2384                   X      Completions.
2386                   $var   Words from the variable var.
2388                   (...)  Words from the given list.
2390                   `...`  Words from the output of command.
2392             select is an optional glob-pattern.  If given, words from only
2393             list that match select are considered and the fignore shell vari‐
2394             able is ignored.  The list types ‘$var’, ‘(...)’, and ‘`...`’ may
2395             not have a select pattern, and ‘x’ uses select as an explanatory
2396             message when the list-choices editor command is used.
2398             suffix is a single character to be appended to a successful com‐
2399             pletion.  If null, no character is appended.  If omitted (in
2400             which case the fourth delimiter can also be omitted), a slash is
2401             appended to directories and a space to other words.
2403             command invoked from list ‘`...`’ has the additional environment
2404             variable COMMAND_LINE set, which contains (as its name indicates)
2405             contents of the current (already typed in) command line.  One can
2406             examine and use contents of the COMMAND_LINE environment variable
2407             in a custom script to build more sophisticated completions (see
2408             completion for svn(1) included in this package).
2410             Now for some examples.  Some commands take only directories as
2411             arguments, so there's no point completing plain files.
2413                   > complete cd 'p/1/d/'
2415             completes only the first word following ‘cd’ (‘p/1’) with a di‐
2416             rectory.  ‘p’-type completion can also be used to narrow down
2417             command completion:
2419                   > co[^D]
2420                   complete compress
2421                   > complete -co* 'p/0/(compress)/'
2422                   > co[^D]
2423                   > compress
2425             This completion completes commands (words in position 0, ‘p/0’)
2426             which begin with ‘co’ (thus matching ‘co*’) to ‘compress’ (the
2427             only word in the list).  The leading ‘-’ indicates that this com‐
2428             pletion is to be used with only ambiguous commands.
2430                   > complete find 'n/-user/u/'
2432             is an example of ‘n’-type completion.  Any word following ‘find’
2433             and immediately following ‘-user’ is completed from the list of
2434             users.
2436                   > complete cc 'c/-I/d/'
2438             demonstrates ‘c’-type completion.  Any word following ‘cc’ and
2439             beginning with ‘-I’ is completed as a directory.  ‘-I’ is not
2440             taken as part of the directory because we used lowercase ‘c’.
2442             Different lists are useful with different commands.
2444                   > complete alias 'p/1/a/'
2445                   > complete man 'p/*/c/'
2446                   > complete set 'p/1/s/'
2447                   > complete true 'p/1/x:Truth has no options./'
2449             These complete words following ‘alias’ with aliases, ‘man’ with
2450             commands, and ‘set’ with shell variables.  true doesn't have any
2451             options, so ‘x’ does nothing when completion is attempted and
2452             prints
2453                   Truth has no options.
2454             when completion choices are listed.
2456             Note that the ‘man’ example, and several other examples below,
2457             could just as well have used ‘'c/*'’ or ‘'n/*'’ as ‘'p/*'’.
2459             Words can be completed from a variable evaluated at completion
2460             time,
2462                   > complete ftp 'p/1/$hostnames/'
2463                   > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu)
2464                   > ftp [^D]
2465                   rtfm.mit.edu tesla.ee.cornell.edu
2466                   > ftp [^C]
2467                   > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net)
2468                   > ftp [^D]
2469                   rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net
2471             or from a command run at completion time:
2473                   > complete kill 'p/*/`ps | awk \{print\ \$1\}`/'
2474                   > kill -9 [^D]
2475                   23113 23377 23380 23406 23429 23529 23530 PID
2477             Note that the complete command does not itself quote its argu‐
2478             ments, so the braces, space and ‘$’ in ‘{print $1}’ must be
2479             quoted explicitly.
2481             One command can have multiple completions:
2483                   > complete dbx 'p/2/(core)/' 'p/*/c/'
2485             completes the second argument to ‘dbx’ with the word ‘core’ and
2486             all other arguments with commands.  Note that the positional com‐
2487             pletion is specified before the next-word completion.  Because
2488             completions are evaluated from left to right, if the next-word
2489             completion were specified first it would always match and the po‐
2490             sitional completion would never be executed.  This is a common
2491             mistake when defining a completion.
2493             The select pattern is useful when a command takes files with only
2494             particular forms as arguments.  For example,
2496                   > complete cc 'p/*/f:*.[cao]/'
2498             completes ‘cc’ arguments to files ending in only ‘.c’, ‘.a’, or
2499             ‘.o’.  select can also exclude files, using negation of a glob-
2500             pattern as described under Filename substitution.  One might use
2502                   > complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'
2504             to exclude precious source code from ‘rm’ completion.  Of course,
2505             one could still type excluded names manually or override the com‐
2506             pletion mechanism using the complete-word-raw or list-choices-raw
2507             editor commands.
2509             The ‘C’, ‘D’, ‘F’, and ‘T’ lists are like ‘c’, ‘d’, ‘f’, and ‘t’
2510             respectively, but they use the select argument in a different
2511             way: to restrict completion to files beginning with a particular
2512             path prefix.  For example, the Elm mail program uses ‘=’ as an
2513             abbreviation for one's mail directory.  One might use
2515                   > complete elm c@=@F:$HOME/Mail/@
2517             to complete
2518                   elm -f =
2519             as if it were
2520                   elm -f ~/Mail/
2521             Note that we used the separator ‘@’ instead of ‘/’ to avoid con‐
2522             fusion with the select argument, and we used ‘$HOME’ instead of
2523             ‘~’ because home directory substitution works at only the begin‐
2524             ning of a word.
2526             suffix is used to add a nonstandard suffix (not space or ‘/’ for
2527             directories) to completed words.
2529                   > complete finger 'c/*@/$hostnames/' 'p/1/u/@'
2531             completes arguments to ‘finger’ from the list of users, appends
2532             an ‘@’, and then completes after the ‘@’ from the ‘hostnames’
2533             variable.  Note again the order in which the completions are
2534             specified.
2536             Finally, here's a complex example for inspiration:
2538                   > complete find \
2539                   'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
2540                   ´n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
2541                   'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
2542                   'n/-type/(b c d f l p s)/' \
2543                   ´c/-/(name newer cpio ncpio exec ok user \
2544                   group fstype type atime ctime depth inum \
2545                   ls mtime nogroup nouser perm print prune \
2546                   size xdev)/' \
2547                   'p/*/d/'
2549             This completes words following ‘-name’, ‘-newer’, ‘-cpio’, or
2550             ‘-ncpio’ (note the pattern which matches both) to files, words
2551             following ‘-exec’ or ‘-ok’ to commands, words following ‘-user’
2552             and ‘-group’ to users and groups respectively and words following
2553             ‘-fstype’ or ‘-type’ to members of the given lists.  It also com‐
2554             pletes the switches themselves from the given list (note the use
2555             of ‘c’-type completion) and completes anything not otherwise com‐
2556             pleted to a directory.  Whew.
2558             Remember that programmed completions are ignored if the word be‐
2559             ing completed is a tilde substitution (beginning with ‘~’) or a
2560             variable (beginning with ‘$’).  See also the uncomplete builtin
2561             command.
2563     continue
2564             Continues execution of the nearest enclosing while or foreach.
2565             The rest of the commands on the current line are executed.
2567     default:
2568             Labels the default case in a switch statement.  It should come
2569             after all case labels.
2571     dirs [-l] [-n|-v]
2572     dirs -S|-L [filename] (+)
2573     dirs -c (+)
2574             The first form prints the directory stack.  The top of the stack
2575             is at the left and the first directory in the stack is the cur‐
2576             rent directory.  With -l, ‘~’ or ‘~name’ in the output is ex‐
2577             panded explicitly to home or the pathname of the home directory
2578             for user name.  (+) With -n, entries are wrapped before they
2579             reach the edge of the screen.  (+) With -v, entries are printed
2580             one per line, preceded by their stack positions.  (+) If more
2581             than one of -n or -v is given, -v takes precedence.  -p is ac‐
2582             cepted but does nothing.
2584             The second form with -S saves the directory stack to filename as
2585             a series of cd and pushd commands.  The second form with -L
2586             sources filename, which is presumably a directory stack file
2587             saved by the -S option or the savedirs mechanism.  In either
2588             case, dirsfile is used if filename is not given and ~/.cshdirs is
2589             used if dirsfile is unset.
2591             Note that login shells do the equivalent of
2592                   dirs -L
2593             on startup and, if savedirs is set,
2594                   dirs -S
2595             before exiting.  Because only ~/.tcshrc is normally sourced be‐
2596             fore ~/.cshdirs, dirsfile should be set in ~/.tcshrc rather than
2597             ~/.login.
2599             The third form clears the directory stack.
2601     echo [-n] word ...
2602             Writes each word to the shell's standard output, separated by
2603             spaces and terminated with a newline.  The echo_style shell vari‐
2604             able may be set to emulate (or not) the flags and escape se‐
2605             quences of the BSD and/or System V versions of echo(1); see
2606             Escape sequences (+) and echo(1).
2608     echotc [-sv] arg ... (+)
2609             Exercises the terminal capabilities (see termcap(5)) in arg.  For
2610             example,
2611                   echotc home
2612             sends the cursor to the home position,
2613                   echotc cm 3 10
2614             sends it to column 3 and row 10, and
2615                   echotc ts 0; echo "This is a test."; echotc fs
2616             prints
2617                   This is a test.
2618             in the status line.
2620             If arg is ‘baud’, ‘cols’, ‘lines’, ‘meta’, or ‘tabs’, prints the
2621             value of that capability (“yes” or “no” indicating that the ter‐
2622             minal does or does not have that capability).  One might use this
2623             to make the output from a shell script less verbose on slow ter‐
2624             minals, or limit command output to the number of lines on the
2625             screen:
2627                   > set history=`echotc lines`
2628                   > @ history--
2630             Termcap strings may contain wildcards which will not echo cor‐
2631             rectly.  One should use double quotes when setting a shell vari‐
2632             able to a terminal capability string, as in the following example
2633             that places the date in the status line:
2635                   > set tosl="`echotc ts 0`"
2636                   > set frsl="`echotc fs`"
2637                   > echo -n "$tosl";date; echo -n "$frsl"
2639             With -s, nonexistent capabilities return the empty string rather
2640             than causing an error.  With -v, messages are verbose.
2642     else
2643     end
2644     endif
2645     endsw   See the description of the foreach, if, switch, and while state‐
2646             ments below.
2648     eval arg ...
2649             Treats the arguments as input to the shell and executes the re‐
2650             sulting command(s) in the context of the current shell.  This is
2651             usually used to execute commands generated as the result of com‐
2652             mand or variable substitution, because parsing occurs before
2653             these substitutions.  See tset(1) for a sample use of eval.
2655     exec command ...
2656             Executes the specified command in place of the current shell.
2658     exit [expr]
2659             The shell exits either with the value of the specified expr (an
2660             expression, as described under Expressions) or, without expr,
2661             with the value 0.
2663     fg [%job ...]
2664             Brings the specified jobs (or, without arguments, the current
2665             job) into the foreground, continuing each if it is stopped.  job
2666             may be a number, a string, ‘’, ‘%’, ‘+’, or ‘-’ as described un‐
2667             der Jobs.  See also the run-fg-editor editor command.
2669     filetest -op file ... (+)
2670             Applies op (which is a file inquiry operator as described under
2671             File inquiry operators) to each file and returns the results as a
2672             space-separated list.
2674     foreach name (wordlist)
2675     ...
2676     end     Successively sets the variable name to each member of wordlist
2677             and executes the sequence of commands between this command and
2678             the matching end.  (Both foreach and end must appear alone on
2679             separate lines.)  The builtin command continue may be used to
2680             continue the loop prematurely and the builtin command break to
2681             terminate it prematurely.  When this command is read from the
2682             terminal, the loop is read once prompting with
2683                   foreach?
2684             (or prompt2) before any statements in the loop are executed.  If
2685             you make a mistake typing in a loop at the terminal you can rub
2686             it out.
2688     getspath (+)
2689             Prints the system execution path.  (TCF only)
2691     getxvers (+)
2692             Prints the experimental version prefix.  (TCF only)
2694     glob word ...
2695             Like echo, but the -n parameter is not recognized and words are
2696             delimited by null characters in the output.  Useful for programs
2697             which wish to use the shell to filename expand a list of words.
2699     goto word
2700             word is filename and command-substituted to yield a string of the
2701             form ‘label’.  The shell rewinds its input as much as possible,
2702             searches for a line of the form
2703                   label:
2704             possibly preceded by blanks or tabs, and continues execution af‐
2705             ter that line.
2707     hashstat
2708             Prints a statistics line indicating how effective the internal
2709             hash table has been at locating commands (and avoiding exec's).
2710             An exec is attempted for each component of the path where the
2711             hash function indicates a possible hit, and in each component
2712             which does not begin with a ‘/’.
2714             On machines without vfork(2), prints only the number and size of
2715             hash buckets.
2717     history [-hTr] [n]
2718     history -S|-L|-M [filename] (+)
2719     history -c (+)
2720             The first form prints the history event list.  If n is given only
2721             the n most recent events are printed or saved.  With -h, the his‐
2722             tory list is printed without leading numbers.  If -T is speci‐
2723             fied, timestamps are printed also in comment form.  This can be
2724             used to produce files suitable for loading with
2725                   history -L
2726             or
2727                   source -h
2729             With -r, the order of printing is most recent first rather than
2730             oldest first.
2732             The second form with -S saves the history list to filename.  If
2733             the first word of the savehist shell variable is set to a number,
2734             at most that many lines are saved.  If the second word of
2735             savehist is set to ‘merge’, the history list is merged with the
2736             existing history file instead of replacing it (if there is one)
2737             and sorted by time stamp.  (+) Merging is intended for an envi‐
2738             ronment like the X Window System with several shells in simulta‐
2739             neous use.  If the second word of savehist is ‘merge’ and the
2740             third word is set to ‘lock’, the history file update will be se‐
2741             rialized with other shell sessions that would possibly like to
2742             merge history at exactly the same time.
2744             The second form with -L appends filename (which is presumably a
2745             history list saved by the -S option or the savehist mechanism) to
2746             the history list.  -M is like -L, but the contents of filename
2747             are merged into the history list and sorted by timestamp.  In ei‐
2748             ther case, histfile is used if filename is not given and
2749             ~/.history is used if histfile is unset.
2751             Note that
2752                   history -L
2753             is exactly like
2754                   source -h
2755             except that it does not require a filename.
2757             Note that login shells do the equivalent of
2758                   history -L
2759             on startup and, if savehist is set,
2760                   history -S
2761             before exiting.  Because only ~/.tcshrc is normally sourced be‐
2762             fore ~/.history, histfile should be set in ~/.tcshrc rather than
2763             ~/.login.
2765             If histlit is set, the first and second forms print and save the
2766             literal (unexpanded) form of the history list.
2768             The third form clears the history list.
2770     hup [command] (+)
2771             With command, runs command such that it will exit on a hangup
2772             signal and arranges for the shell to send it a hangup signal when
2773             the shell exits.  Note that commands may set their own response
2774             to hangups, overriding hup.  Without an argument, causes the non-
2775             interactive shell only to exit on a hangup for the remainder of
2776             the script.  See also Signal handling and the nohup builtin com‐
2777             mand.
2779     if (expr) command
2780             If expr (an expression, as described under Expressions) evaluates
2781             true, then command is executed.  Variable substitution on command
2782             happens early, at the same time it does for the rest of the if
2783             command.  command must be a simple command, not an alias, a pipe‐
2784             line, a command list or a parenthesized command list, but it may
2785             have arguments.  Input/output redirection occurs even if expr is
2786             false and command is thus not executed; this is a bug.
2788     if (expr) then
2789     ...
2790     else if (expr2) then
2791     ...
2792     else
2793     ...
2794     endif   If the specified expr is true then the commands to the first else
2795             are executed; otherwise if expr2 is true then the commands to the
2796             second else are executed, etc.  Any number of else if pairs are
2797             possible; only one endif is needed.  The else part is likewise
2798             optional.  (The words else and endif must appear at the beginning
2799             of input lines; the if must appear alone on its input line or af‐
2800             ter an else.)
2802     inlib shared-library ... (+)
2803             Adds each shared-library to the current environment.  There is no
2804             way to remove a shared library.  (Domain/OS only)
2806     jobs [-l]
2807     jobs -Z [title] (+)
2808             The first form lists the active jobs.  With -l, lists process IDs
2809             in addition to the normal information.  On TCF systems, prints
2810             the site on which each job is executing.
2812             The second form with the -Z option sets the process title to
2813             title using setproctitle(3) where available.  If no title is pro‐
2814             vided, the process title will be cleared.
2816     kill -l
2817     kill [-s signal] %job|pid ...
2818             The first form lists the signal names.
2820             The second form sends the specified signal (or, if none is given,
2821             the TERM (terminate) signal) to the specified jobs or processes.
2822             job may be a number, a string, ‘’, ‘%’, ‘+’, or ‘-’ as described
2823             under Jobs.  Signals are either given by number or by name (as
2824             given in /usr/include/signal.h, stripped of the prefix ‘SIG’).
2826             There is no default job; entering just
2827                   kill
2828             does not send a signal to the current job.  If the signal being
2829             sent is TERM (terminate) or HUP (hangup), then the job or process
2830             is sent a CONT (continue) signal as well.
2832     limit [-h] [resource [maximum-use]]
2833             Limits the consumption by the current process and each process it
2834             creates to not individually exceed maximum-use on the specified
2835             resource.
2837             If no maximum-use is given, then the current limit for resource
2838             is printed.
2840             If no resource is given, then all limitations are given.
2842             If the -h flag is given, the hard limits are used instead of the
2843             current limits.  The hard limits impose a ceiling on the values
2844             of the current limits.  Only the super-user may raise the hard
2845             limits, but a user may lower or raise the current limits within
2846             the legal range.
2848             Controllable resource types currently include (if supported by
2849             the OS):
2851                   resource      Resource description
2853                   concurrency   Maximum number of threads for this process.
2855                   coredumpsize  Size of the largest core dump that will be
2856                                 created.
2858                   cputime       Maximum number of cpu-seconds to be used by
2859                                 each process.
2861                   datasize      Maximum growth of the data+stack region via
2862                                 sbrk(2) beyond the end of the program text.
2864                   descriptors or openfiles
2865                                 Maximum number of open files for this
2866                                 process.
2868                   filesize      Largest single file which can be created.
2870                   heapsize      Maximum amount of memory a process may allo‐
2871                                 cate per brk(2) system call.
2873                   kqueues       Maximum number of kqueues allocated for this
2874                                 process.
2876                   maxlocks      Maximum number of locks for this user.
2878                   maxmessage    Maximum number of bytes in POSIX mqueues for
2879                                 this user.
2881                   maxnice       Maximum nice priority the user is allowed to
2882                                 raise mapped from [19...-20] to [0...39] for
2883                                 this user.
2885                   maxproc       Maximum number of simultaneous processes for
2886                                 this user id.
2888                   maxrtprio     Maximum realtime priority for this user.
2890                   maxrttime     Timeout for RT tasks in microseconds for this
2891                                 user.
2893                   maxsignal     Maximum number of pending signals for this
2894                                 user.
2896                   maxthread     Maximum number of simultaneous threads
2897                                 (lightweight processes) for this user id.
2899                   memorylocked  Maximum size which a process may lock into
2900                                 memory using mlock(2).
2902                   memoryuse     Maximum amount of physical memory a process
2903                                 may have allocated to it at a given time.
2905                   posixlocks    Maximum number of POSIX advisory locks for
2906                                 this user.
2908                   pseudoterminals
2909                                 Maximum number of pseudo-terminals for this
2910                                 user.
2912                   sbsize        Maximum size of socket buffer usage for this
2913                                 user.
2915                   stacksize     Maximum size of the automatically-extended
2916                                 stack region.
2918                   swapsize      Maximum amount of swap space reserved or used
2919                                 for this user.
2921                   threads       Maximum number of threads for this process.
2923                   vmemoryuse    NOTE: Changing this value has no effect. Sup‐
2924                                 port has been removed from Linux kernel v2.6
2925                                 and newer.  Maximum amount of virtual memory
2926                                 a process may have allocated to it at a given
2927                                 time (address space).
2929             maximum-use may be given as a (floating point or integer) number
2930             followed by a scale factor.  For all limits other than cputime
2931             the default scale is ‘k’ or ‘kilobytes’ (1024 bytes); a scale
2932             factor of ‘m’ or ‘megabytes’ (1048576 bytes) or ‘g’ or
2933             ‘gigabytes’ (1073741824 bytes) may also be used.  For cputime the
2934             default scaling is ‘seconds’, while ‘m’ for minutes or ‘h’ for
2935             hours, or a time of the form ‘mm:ss’ giving minutes and seconds
2936             may be used.
2938             If maximum-use is ‘unlimited’, then the limitation on the speci‐
2939             fied resource is removed (this is equivalent to the unlimit
2940             builtin command).
2942             For both resource names and scale factors, unambiguous prefixes
2943             of the names suffice.
2945     log (+)
2946             Prints the watch shell variable and reports on each user indi‐
2947             cated in watch who is logged in, regardless of when they last
2948             logged in.  See also watchlog.
2950     login   Terminates a login shell, replacing it with an instance of
2951             /bin/login.  This is one way to log off, included for compatibil‐
2952             ity with sh(1).
2954     logout  Terminates a login shell.  Especially useful if ignoreeof is set.
2956     ls-F [-switch ...] [file ...] (+)
2957             Lists files like
2958                   ls -F
2959             but much faster.
2961             ls-F identifies each type of special file in the listing with a
2962             special character suffix:
2964                   Suffix  Special file type
2966                   /       Directory.
2967                   *       Executable.
2968                   #       Block device.
2969                   %       Character device.
2970                   |       Named pipe (systems with named pipes only).
2971                   =       Socket (systems with sockets only).
2972                   @       Symbolic link (systems with symbolic links only).
2973                   +       Hidden directory (AIX only) or context dependent
2974                           (HP/UX only).
2975                   :       Network special (HP/UX only).
2977             If the listlinks shell variable is set, symbolic links are iden‐
2978             tified in more detail (on only systems that have them, of
2979             course):
2981                   Suffix  Symbolic link type
2983                   @       Symbolic link to a non-directory.
2984                   >       Symbolic link to a directory.
2985                   &       Orphaned (broken) symbolic link.
2987             listlinks also slows down ls-F and causes partitions holding
2988             files pointed to by symbolic links to be mounted.
2990             If the listflags shell variable is set to ‘x’, ‘a’, or ‘A’, or
2991             any combination thereof (e.g., ‘xA’), they are used as flags to
2992             ls-F, making it act like
2993                   ls -xF
2994                   ls -Fa
2995                   ls -FA
2997             or a combination, for example
2998                   ls -FxA
3000             On machines where
3001                   ls -C
3002             is not the default, ls-F acts like
3003                   ls -CF
3004             unless listflags contains an ‘x’, in which case it acts like
3005                   ls -xF
3007             ls-F passes its arguments to ls(1) if it is given any switches,
3008             so
3009                   alias ls ls-F
3010             generally does the right thing.
3012             The ls-F builtin can list files using different colors depending
3013             on the file type or extension.  See the color shell variable and
3014             the CLICOLOR_FORCE, LSCOLORS, and LS_COLORS environment vari‐
3015             ables.
3017     migrate [-site] pid|%jobid ... (+)
3018     migrate -site (+)
3019             The first form migrates the process or job to the site specified
3020             or the default site determined by the system path.  (TCF only)
3022             The second form is equivalent to
3023                   migrate -site $$
3024             in that it migrates the current process to the specified site.
3025             Migrating the shell itself can cause unexpected behavior, because
3026             the shell does not like to lose its tty.  (TCF only)
3028     newgrp [-] [group] (+)
3029             Equivalent to
3030                   exec newgrp
3031             as per newgrp(1).  Available only if the shell was so compiled;
3032             see the version shell variable.
3034     nice [+number] [command]
3035             Sets the scheduling priority for the shell to number, or, without
3036             number, to 4.  With command, runs command at the appropriate pri‐
3037             ority.  The greater the number, the less cpu the process gets.
3038             The super-user may specify negative priority by using
3039                   nice -number ...
3041             command is always executed in a sub-shell, and the restrictions
3042             placed on commands in simple if statements apply.
3044     nohup [command]
3045             With command, runs command such that it will ignore hangup sig‐
3046             nals.  Note that commands may set their own response to hangups,
3047             overriding nohup.
3049             Without an argument, causes the non-interactive shell only to ig‐
3050             nore hangups for the remainder of the script.  See also Signal
3051             handling and the hup builtin command.
3053     notify [%job ...]
3054             Causes the shell to notify the user asynchronously when the sta‐
3055             tus of any of the specified jobs (or, without %job, the current
3056             job) changes, instead of waiting until the next prompt as is
3057             usual.  job may be a number, a string, ‘’, ‘%’, ‘+’, or ‘-’ as
3058             described under Jobs.  See also the notify shell variable.
3060     onintr [-|label]
3061             Controls the action of the shell on interrupts.  Without argu‐
3062             ments, restores the default action of the shell on interrupts,
3063             which is to terminate shell scripts or to return to the terminal
3064             command input level.
3066             With ‘-’, causes all interrupts to be ignored.
3068             With label, causes the shell to execute a
3069                   goto label
3070             when an interrupt is received or a child process terminates be‐
3071             cause it was interrupted.
3073             onintr is ignored if the shell is running detached and in system
3074             startup files (see FILES), where interrupts are disabled anyway.
3076     popd [-p] [-l] [-n|-v] [+n]
3077             Without arguments, pops the directory stack and returns to the
3078             new top directory.
3080             With a number ‘+n’, discards the nth entry in the stack.
3082             Finally, all forms of popd print the final directory stack, just
3083             like dirs.  The pushdsilent shell variable can be set to prevent
3084             this and the -p flag can be given to override pushdsilent.  The
3085             -l, -n, and -v flags have the same effect on popd as on dirs.
3086             (+)
3088     printenv [name] (+)
3089             Prints the names and values of all environment variables or, with
3090             name, the value of the environment variable name.
3092     pushd [-p] [-l] [-n|-v] [name|+n]
3093             Without arguments, exchanges the top two elements of the direc‐
3094             tory stack.  If pushdtohome is set, pushd without arguments acts
3095             as
3096                   pushd ~
3097             like cd.  (+)
3099             With name, pushes the current working directory onto the direc‐
3100             tory stack and changes to name.  If name is ‘-’ it is interpreted
3101             as the previous working directory (see Filename substitution).
3102             (+) If dunique is set, pushd removes any instances of name from
3103             the stack before pushing it onto the stack.  (+)
3105             With a number ‘+n’, rotates the nth element of the directory
3106             stack around to be the top element and changes to it.  If
3107             dextract is set, however,
3108                   pushd +n
3109             extracts the nth directory, pushes it onto the top of the stack
3110             and changes to it.  (+)
3112             Finally, all forms of pushd print the final directory stack, just
3113             like dirs.  The pushdsilent shell variable can be set to prevent
3114             this and the -p flag can be given to override pushdsilent.  The
3115             -l, -n, and -v flags have the same effect on pushd as on dirs.
3116             (+)
3118     rehash  Causes the internal hash table of the contents of the directories
3119             in the path variable to be recomputed.  This is needed if the
3120             autorehash shell variable is not set and new commands are added
3121             to directories in path while you are logged in.  With autorehash,
3122             a new command will be found automatically, except in the special
3123             case where another command of the same name which is located in a
3124             different directory already exists in the hash table.  Also
3125             flushes the cache of home directories built by tilde expansion.
3127     repeat count command
3128             The specified command, which is subject to the same restrictions
3129             as the command in the one line if statement above, is executed
3130             count times.  I/O redirections occur exactly once, even if count
3131             is 0.
3133     rootnode //nodename (+)
3134             Changes the rootnode to //nodename, so that ‘/’ will be inter‐
3135             preted as ‘//nodename’.  (Domain/OS only)
3137     sched (+)
3138     sched [+]hh:mm command (+)
3139     sched -n (+)
3140             The first form prints the scheduled-event list.  The sched shell
3141             variable may be set to define the format in which the scheduled-
3142             event list is printed.
3144             The second form adds command to the scheduled-event list.  For
3145             example,
3147                   > sched 11:00 echo It\'s eleven o\'clock.
3149             causes the shell to echo
3150                   It's eleven o'clock.
3151             at 11 AM.
3153             The time may be in 12-hour AM/PM format
3155                   > sched 5pm set prompt='[%h] It\'s after 5; go home: >'
3157             or may be relative to the current time:
3159                   > sched +2:15 /usr/lib/uucp/uucico -r1 -sother
3161             A relative time specification may not use AM/PM format.
3163             The third form removes item n from the event list:
3165                   > sched
3166                   1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
3167                   2  Wed Apr  4 17:00  set prompt=[%h] It's after 5; go home: >
3168                   > sched -2
3169                   > sched
3170                   1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
3172             A command in the scheduled-event list is executed just before the
3173             first prompt is printed after the time when the command is sched‐
3174             uled.  It is possible to miss the exact time when the command is
3175             to be run, but an overdue command will execute at the next
3176             prompt.  A command which comes due while the shell is waiting for
3177             user input is executed immediately.  However, normal operation of
3178             an already-running command will not be interrupted so that a
3179             scheduled-event list element may be run.
3181             This mechanism is similar to, but not the same as, the at(1) com‐
3182             mand on some Unix systems.  Its major disadvantage is that it may
3183             not run a command at exactly the specified time.  Its major ad‐
3184             vantage is that because sched runs directly from the shell, it
3185             has access to shell variables and other structures.  This pro‐
3186             vides a mechanism for changing one's working environment based on
3187             the time of day.
3189     set
3190     set name ...
3191     set name=word ...
3192     set [-r] [-f|-l] name=(wordlist) ... (+)
3193     set name[index]=word ...
3194     set -r (+)
3195     set -r name ... (+)
3196     set -r name=word ... (+)
3197             The first form of the command prints the value of all shell vari‐
3198             ables.  Variables which contain more than a single word print as
3199             a parenthesized word list.
3201             The second form sets name to the null string.
3203             The third form sets name to the single word.
3205             The fourth form sets name to the list of words in wordlist.
3207             In all cases the value is command and filename expanded.  If -r
3208             is specified, the value is set read-only.  If -f or -l are speci‐
3209             fied, set only unique words keeping their order.  -f prefers the
3210             first occurrence of a word, and -l the last.
3212             The fifth form sets the index'th component of name to word; this
3213             component must already exist.
3215             The sixth form lists only the names of all shell variables that
3216             are read-only.
3218             The seventh form makes name read-only, whether or not it has a
3219             value.
3221             The eighth form is the same as the third form, but make name
3222             read-only at the same time.
3224             These arguments can be repeated to set and/or make read-only mul‐
3225             tiple variables in a single set command.  Note, however, that
3226             variable expansion happens for all arguments before any setting
3227             occurs.  Note also that ‘=’ can be adjacent to both name and word
3228             or separated from both by whitespace, but cannot be adjacent to
3229             only one or the other.  See also the unset builtin command.
3231     setenv [name [value]]
3232             Without arguments, prints the names and values of all environment
3233             variables.
3235             With name, sets the environment variable name to value or, with‐
3236             out value, to the null string.
3238     setpath path (+)
3239             Equivalent to setpath(1).  (Mach only)
3241     setspath LOCAL|site|cpu ... (+)
3242             Sets the system execution path.  (TCF only)
3244     settc cap value (+)
3245             Tells the shell to believe that the terminal capability cap (as
3246             defined in termcap(5)) has the value value.  No sanity checking
3247             is done.  Concept terminal users may have to
3248                   settc xn no
3249             to get proper wrapping at the rightmost column.
3251     setty [-d|-q|-x] [-a] [[+|-]mode] (+)
3252             Controls which tty modes (see Terminal management (+)) the shell
3253             does not allow to change.  -d, -q, or -x tells setty to act on
3254             the ‘edit’, ‘quote’, or ‘execute’ set of tty modes respectively;
3255             without -d, -q, or -x, ‘execute’ is used.
3257             Without other arguments, setty lists the modes in the chosen set
3258             which are fixed on (‘+mode’) or off (‘-mode’).  The available
3259             modes, and thus the display, vary from system to system.  With
3260             -a, lists all tty modes in the chosen set whether or not they are
3261             fixed.  With +mode, -mode, or mode, fixes mode on or off or re‐
3262             moves control from mode in the chosen set.  For example,
3263                   setty +echok echoe
3264             fixes ‘echok’ mode on and allows commands to turn ‘echoe’ mode on
3265             or off, both when the shell is executing commands.
3267     setxvers [string] (+)
3268             Set the experimental version prefix to string, or removes it if
3269             string is omitted.  (TCF only)
3271     shift [variable]
3272             Without arguments, discards argv[1] and shifts the members of
3273             argv to the left.  It is an error for argv not to be set or to
3274             have fewer than one word as value.
3276             With variable, performs the same function on variable.
3278     source [-h] name [args ...]
3279             The shell reads and executes commands from name.  The commands
3280             are not placed on the history list.  If any args are given, they
3281             are placed in argv.  (+) source commands may be nested; if they
3282             are nested too deeply the shell may run out of file descriptors.
3283             An error in a source at any level terminates all nested source
3284             commands.
3286             With -h, commands are placed on the history list instead of being
3287             executed, much like
3288                   history -L
3290     stop %job|pid ...
3291             Stops the specified jobs or processes which are executing in the
3292             background.  job may be a number, a string, ‘’, ‘%’, ‘+’, or ‘-’
3293             as described under Jobs.
3295             There is no default job; entering just
3296                   stop
3297             does not stop the current job.
3299     suspend
3300             Causes the shell to stop in its tracks, much as if it had been
3301             sent a stop signal with ^Z.  This is most often used to stop
3302             shells started by su(1).
3304     switch (string)
3305     case str1:
3306         ...
3307         breaksw
3308     ...
3309     default:
3310         ...
3311         breaksw
3312     endsw   Each case label is successively matched, against the specified
3313             string which is first command and filename expanded.  The file
3314             metacharacters ‘*’, ‘?’, and ‘[...]’ may be used in the case la‐
3315             bels, which are variable expanded.  If none of the labels match
3316             before a default label is found, then the execution begins after
3317             the default label.  Each case label and the default label must
3318             appear at the beginning of a line.  The command breaksw causes
3319             execution to continue after the endsw.  Otherwise control may
3320             fall through case labels and default labels as in C.  If no label
3321             matches and there is no default, execution continues after the
3322             endsw.
3324     telltc (+)
3325             Lists the values of all terminal capabilities (see termcap(5)).
3327     termname [termtype] (+)
3328             Tests if termtype (or the current value of TERM if no termtype is
3329             given) has an entry in the hosts termcap(5) or terminfo(5) data‐
3330             base.  Prints the terminal type to stdout and returns 0 if an en‐
3331             try is present otherwise returns 1.
3333     time [command]
3334             Executes command (which must be a simple command, not an alias, a
3335             pipeline, a command list or a parenthesized command list) and
3336             prints a time summary as described under the time variable.  If
3337             necessary, an extra shell is created to print the time statistic
3338             when the command completes.
3340             Without command, prints a time summary for the current shell and
3341             its children.
3343     umask [value]
3344             Sets the file creation mask to value, which is given in octal.
3345             Common values for the mask are 002, giving all access to the
3346             group and read and execute access to others, and 022, giving read
3347             and execute access to the group and others.
3349             Without value, prints the current file creation mask.
3351     unalias pattern
3352             Removes all aliases whose names match pattern.  Thus
3353                   unalias *
3354             removes all aliases.  It is not an error for nothing to be
3355             unaliased.
3357     uncomplete pattern (+)
3358             Removes all completions whose names match pattern.  Thus
3359                   uncomplete *
3360             removes all completions.  It is not an error for nothing to be
3361             uncompleted.
3363     unhash  Disables use of the internal hash table to speed location of exe‐
3364             cuted programs.
3366     universe universe (+)
3367             Sets the universe to universe.  (Masscomp/RTU only)
3369     unlimit [-hf] [resource]
3370             Removes the limitation on resource or, if no resource is speci‐
3371             fied, all resource limitations.
3373             With -h, the corresponding hard limits are removed.  Only the su‐
3374             per-user may do this.
3376             Note that unlimit may not exit successful, since most systems do
3377             not allow descriptors to be unlimited.
3379             With -f errors are ignored.
3381     unset pattern
3382             Removes all variables whose names match pattern, unless they are
3383             read-only.  Thus
3384                   unset *
3385             removes all variables unless they are read-only; this is a bad
3386             idea.
3388             It is not an error for nothing to be unset.
3390     unsetenv pattern
3391             Removes all environment variables whose names match pattern.
3392             Thus
3393                   unsetenv *
3394             removes all environment variables; this is a bad idea.
3396             It is not an error for nothing to be unsetenved.
3398     ver [systype [command]] (+)
3399             Without arguments, prints SYSTYPE.
3401             With systype, sets SYSTYPE to systype.
3403             With systype and command, executes command under systype.
3404             systype may be ‘bsd4.3’ or ‘sys5.3’.
3406             (Domain/OS only)
3408     wait    The shell waits for all background jobs.  If the shell is inter‐
3409             active, an interrupt will disrupt the wait and cause the shell to
3410             print the names and job numbers of all outstanding jobs.
3412     warp universe (+)
3413             Sets the universe to universe.  (Convex/OS only)
3415     watchlog (+)
3416             An alternate name for the log builtin command.  Available only if
3417             the shell was so compiled; see the version shell variable.
3419     where command (+)
3420             Reports all known instances of command, including aliases,
3421             builtins and executables in path.
3423     which command (+)
3424             Displays the command that will be executed by the shell after
3425             substitutions, path searching, etc.  The builtin command is just
3426             like which(1), but it correctly reports tcsh aliases and builtins
3427             and is 10 to 100 times faster.  See also the which-command editor
3428             command.
3430     while (expr)
3431     ...
3432     end     Executes the commands between the while and the matching end
3433             while expr (an expression, as described under Expressions) evalu‐
3434             ates non-zero.  while and end must appear alone on their input
3435             lines.  break and continue may be used to terminate or continue
3436             the loop prematurely.  If the input is a terminal, the user is
3437             prompted the first time through the loop as with foreach.
3439   Special aliases (+)
3440     If set, each of these aliases executes automatically at the indicated
3441     time.  They are all initially undefined.
3443     Supported special aliases are:
3445     beepcmd
3446             Runs when the shell wants to ring the terminal bell.
3448     cwdcmd  Runs after every change of working directory.  For example, if
3449             the user is working on an X window system using xterm(1) and a
3450             re-parenting window manager that supports title bars such as
3451             twm(1) and does
3453                   > alias cwdcmd  'echo -n "^[]2;${HOST}:$cwd ^G"'
3455             then the shell will change the title of the running xterm(1) to
3456             be the name of the host, a ‘:’, and the full current working di‐
3457             rectory.  A fancier way to do that is
3459                   > alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'
3461             This will put the hostname and working directory on the title bar
3462             but only the hostname in the icon manager menu.
3464             Note that putting a cd, pushd, or popd in cwdcmd may cause an in‐
3465             finite loop.  It is the author's opinion that anyone doing so
3466             will get what they deserve.
3468     jobcmd  Runs before each command gets executed, or when the command
3469             changes state.  This is similar to postcmd, but it does not print
3470             builtins.
3472                   > alias jobcmd  'echo -n "^[]2\;\!#:q^G"'
3474             then executing
3475                   vi foo.c
3476             will put the command string in the xterm title bar.
3478     helpcommand
3479             Invoked by the run-help editor command.  The command name for
3480             which help is sought is passed as sole argument.  For example, if
3481             one does
3483                   > alias helpcommand '\!:1 --help'
3485             then the help display of the command itself will be invoked, us‐
3486             ing the GNU help calling convention.
3488             Currently there is no easy way to account for various calling
3489             conventions (e.g., the customary Unix ‘-h’), except by using a
3490             table of many commands.
3492     periodic
3493             Runs every tperiod minutes.  This provides a convenient means for
3494             checking on common but infrequent changes such as new mail.  For
3495             example, if one does
3497                   > set tperiod = 30
3498                   > alias periodic checknews
3500             then the checknews(1) program runs every 30 minutes.
3502             If periodic is set but tperiod is unset or set to 0, periodic be‐
3503             haves like precmd.
3505     precmd  Runs just before each prompt is printed.  For example, if one
3506             does
3508                   > alias precmd date
3510             then date(1) runs just before the shell prompts for each command.
3512             There are no limits on what precmd can be set to do, but discre‐
3513             tion should be used.
3515     postcmd
3516             Runs before each command gets executed.
3518                   > alias postcmd  'echo -n "^[]2\;\!#:q^G"'
3520             then executing
3521                   vi foo.c
3522             will put the command string in the xterm title bar.
3524     shell   Specifies the interpreter for executable scripts which do not
3525             themselves specify an interpreter.  The first word should be a
3526             full path name to the desired interpreter (e.g., ‘/bin/csh’ or
3527             ‘/usr/local/bin/tcsh’).
3529   Special shell variables
3530     The variables described in this section have special meaning to the
3531     shell.
3533     The shell sets addsuffix, argv, autologout, csubstnonl, command,
3534     echo_style, edit, gid, group, home, loginsh, oid, path, prompt, prompt2,
3535     prompt3, shell, shlvl, tcsh, term, tty, uid, user, and version at
3536     startup; they do not change thereafter unless changed by the user.  The
3537     shell updates cwd, dirstack, owd, and status when necessary, and sets
3538     logout on logout.
3540     The shell synchronizes group, home, path, shlvl, term, and user with the
3541     environment variables of the same names: whenever the environment vari‐
3542     able changes the shell changes the corresponding shell variable to match
3543     (unless the shell variable is read-only) and vice versa.  Note that al‐
3544     though cwd and PWD have identical meanings, they are not synchronized in
3545     this manner, and that the shell automatically converts between the dif‐
3546     ferent formats of path and PATH.
3548     Supported special shell variables are:
3550     addsuffix (+)
3551             If set, filename completion adds ‘/’ to the end of directories
3552             and a space to the end of normal files when they are matched ex‐
3553             actly.  Set by default.
3555     afsuser (+)
3556             If set, autologout's autolock feature uses its value instead of
3557             the local username for kerberos authentication.
3559     ampm (+)
3560             If set, all times are shown in 12-hour AM/PM format.
3562     anyerror (+)
3563             This variable selects what is propagated to the value of the
3564             status variable.  For more information see the description of the
3565             status variable below.
3567     argv    The arguments to the shell.  Positional parameters are taken from
3568             argv, i.e., ‘$1’ is replaced by ‘$argv[1]’, etc.  Set by default,
3569             but usually empty in interactive shells.
3571     autocorrect (+)
3572             If set, the spell-word editor command is invoked automatically
3573             before each completion attempt.
3575     autoexpand (+)
3576             If set, the expand-history editor command is invoked automati‐
3577             cally before each completion attempt.
3579             If this is set to ‘onlyhistory’, then only history will be ex‐
3580             panded and a second completion will expand filenames.
3582     autolist (+)
3583             If set, possibilities are listed after an ambiguous completion.
3585             If set to ‘ambiguous’, possibilities are listed only when no new
3586             characters are added by completion.
3588     autologout (+)
3589             The first word is the number of minutes of inactivity before au‐
3590             tomatic logout.  The optional second word is the number of min‐
3591             utes of inactivity before automatic locking.  When the shell au‐
3592             tomatically logs out, it prints
3593                   auto-logout
3594             sets the variable logout to ‘automatic’ and exits.  When the
3595             shell automatically locks, the user is required to enter their
3596             password to continue working.  Five incorrect attempts result in
3597             automatic logout.
3599             Set to ‘60’ (automatic logout after 60 minutes, and no locking)
3600             by default in login and superuser shells, but not if the shell
3601             thinks it is running under a window system (i.e., the DISPLAY en‐
3602             vironment variable is set), the tty is a pseudo-tty (pty) or the
3603             shell was not so compiled (see the version shell variable).
3605             Unset autologout or set it to ‘0’ to disable automatic logout.
3606             See also the afsuser and logout shell variables.
3608     autorehash (+)
3609             If set, the internal hash table of the contents of the directo‐
3610             ries in the path variable will be recomputed if a command is not
3611             found in the hash table.  In addition, the list of available com‐
3612             mands will be rebuilt for each command completion or spelling
3613             correction attempt if set to ‘complete’ or ‘correct’ respec‐
3614             tively; if set to ‘always’, this will be done for both cases.
3616     backslash_quote (+)
3617             If set, backslashes (`\') always quote ‘\’, ‘'’, and ‘"’.  This
3618             may make complex quoting tasks easier, but it can cause syntax
3619             errors in csh(1) scripts.
3621     catalog
3622             The file name of the message catalog.  If set, tcsh uses
3623             tcsh.${catalog} as a message catalog instead of default tcsh.
3625     cdpath  A list of directories in which cd should search for subdirecto‐
3626             ries if they aren't found in the current directory.
3628     cdtohome (+)
3629             If not set, cd requires a directory name, and will not go to the
3630             home directory if it's omitted.  This is set by default.
3632     color   If set, it enables color display for the builtin ls-F and it
3633             passes --color=auto to ls(1) (or --color=always if CLICOLOR_FORCE
3634             is set).  Alternatively, it can be set to only ‘ls-F’ or only
3635             ‘ls’ to enable color for a specific command.  Setting it to noth‐
3636             ing is equivalent to setting it to ‘(ls-F ls)’.  Color is dis‐
3637             abled if the output is not directed to a terminal, unless
3638             CLICOLOR_FORCE is set.
3640     colorcat
3641             If set, it enables color escape sequence for NLS message files,
3642             and display colorful NLS messages.
3644     command (+)
3645             If set, the command which was passed to the shell with the -c
3646             flag.
3648     compat_expr (+)
3649             If set, the shell will evaluate expressions right to left, like
3650             the original csh(1).
3652     complete (+)
3653             If set to ‘igncase’, the completion becomes case insensitive.
3655             If set to ‘enhance’, completion ignores case and considers hy‐
3656             phens and underscores to be equivalent; it will also treat peri‐
3657             ods, hyphens and underscores (‘.’, ‘-’, and ‘_’) as word separa‐
3658             tors.
3660             If set to ‘Enhance’, completion matches uppercase and underscore
3661             characters explicitly and matches lowercase and hyphens in a
3662             case-insensitive manner; it will treat periods, hyphens and un‐
3663             derscores as word separators.
3665     continue (+)
3666             If set to a list of commands, the shell will continue the listed
3667             commands, instead of starting a new one.
3669     continue_args (+)
3670             Same as continue, but the shell will execute:
3672                   echo `pwd` $argv > ~/.<cmd>_pause; %<cmd>
3674     correct (+)
3675             If set to ‘cmd’, commands are automatically spelling-corrected.
3677             If set to ‘complete’, commands are automatically completed.
3679             If set to ‘all’, the entire command line is corrected.
3681     csubstnonl (+)
3682             If set, newlines and carriage returns in command substitution are
3683             replaced by spaces.  Set by default.
3685     cwd     The full pathname of the current directory.  See also the
3686             dirstack and owd shell variables.
3688     dextract (+)
3689             If set,
3690                   pushd +n
3691             extracts the nth directory from the directory stack rather than
3692             rotating it to the top.
3694     dirsfile (+)
3695             The default location in which
3696                   dirs -S
3697             and
3698                   dirs -L
3699             look for a history file.  If unset, ~/.cshdirs is used.  Because
3700             only ~/.tcshrc is normally sourced before ~/.cshdirs, dirsfile
3701             should be set in ~/.tcshrc rather than ~/.login.
3703     dirstack (+)
3704             An array of all the directories on the directory stack.
3705             ‘$dirstack[1]’ is the current working directory, ‘$dirstack[2]’
3706             the first directory on the stack, etc.  Note that the current
3707             working directory is ‘$dirstack[1]’ but ‘=0’ in directory stack
3708             substitutions, etc.  One can change the stack arbitrarily by set‐
3709             ting dirstack, but the first element (the current working direc‐
3710             tory) is always correct.  See also the cwd and owd shell vari‐
3711             ables.
3713     dspmbyte (+)
3714             Has an effect only if ‘dspm’ is listed as part of the version
3715             shell variable.
3717             If set to ‘euc’, it enables display and editing EUC-kanji(Japa‐
3718             nese) code.
3720             If set to ‘sjis’, it enables display and editing Shift-JIS(Japa‐
3721             nese) code.
3723             If set to ‘big5’, it enables display and editing Big5(Chinese)
3724             code.
3726             If set to ‘utf8’, it enables display and editing Utf8(Unicode)
3727             code.
3729             If set to exactly 256 characters in the following format, it en‐
3730             ables display and editing of original multi-byte code format:
3732                   > set dspmbyte = NNN...[250 characters]...NNN
3734             Each character N in the 256 character value corresponds (from
3735             left to right) to the ASCII codes 0x00, 0x01, 0x02, ..., 0xfd,
3736             0xfe, 0xff at the same index.  Each character is set to number 0,
3737             1, 2 or 3, with the meaning:
3739                   Number  Multi-byte purpose
3741                   0       Not used for multi-byte characters.
3742                   1       Used for the first byte of a multi-byte character.
3743                   2       Used for the second byte of a multi-byte character.
3744                   3       Used for both the first byte and second byte of a
3745                           multi-byte character.
3747             For example, if set to 256 characters starting with ‘001322’, the
3748             value is interpreted as:
3750                   Character    ASCII    Multi-byte character use
3752                   0            0x00     Not used.
3753                   0            0x01     Not used.
3754                   1            0x02     First byte.
3755                   3            0x03     First byte and second byte.
3756                   2            0x04     Second byte.
3757                   2            0x05     Second byte.
3759             The GNU coreutils version of ls(1) cannot display multi-byte
3760             filenames without the -N (--literal) option.  If you are using
3761             this version, set the second word of dspmbyte to ‘ls’.  If not,
3762             for example,
3763                   ls-F -l
3764             cannot display multi-byte filenames.
3766             Note that this variable can only be used if KANJI and DSPMBYTE
3767             has been defined at compile time.
3769     dunique (+)
3770             If set, pushd removes any instances of name from the stack before
3771             pushing it onto the stack.
3773     echo    If set, each command with its arguments is echoed just before it
3774             is executed.  For non-builtin commands all expansions occur be‐
3775             fore echoing.  Builtin commands are echoed before command and
3776             filename substitution, because these substitutions are then done
3777             selectively.  Set by the -x command line option.
3779     echo_style (+)
3780             The style of the echo builtin.  May be set to:
3782                   Value  echo style
3784                   bsd    Don't echo a newline if the first argument is -n;
3785                          the default for csh(1).
3787                   sysv   Recognize backslashed escape sequences in echo
3788                          strings.
3790                   both   Recognize both the -n flag and backslashed escape
3791                          sequences; the default for tcsh.
3793                   none   Recognize neither.
3795             Set by default to the local system default.  The BSD and System V
3796             options are described in the echo(1) man pages on the appropriate
3797             systems.
3799     edit (+)
3800             If set, the command-line editor is used.  Set by default in in‐
3801             teractive shells.
3803     editors (+)
3804             A list of command names for the run-fg-editor editor command to
3805             match.  If not set, the EDITOR (‘ed’ if unset) and VISUAL (‘vi’
3806             if unset) environment variables will be used instead.
3808     ellipsis (+)
3809             If set, the ‘%c’, ‘%.’, and ‘%C’ prompt sequences (see the prompt
3810             shell variable) indicate skipped directories with an ellipsis
3811             (‘...’) instead of ‘/<skipped>’.
3813     euid (+)
3814             The user's effective user ID.
3816     euser (+)
3817             The first matching passwd entry name corresponding to the effec‐
3818             tive user ID.
3820     fignore (+)
3821             Lists file name suffixes to be ignored by completion.
3823     filec   In tcsh, completion is always used and this variable is ignored
3824             by default.
3826             If edit is unset, then the traditional csh(1) completion is used.
3828             If set in csh(1), filename completion is used.
3830     gid (+)
3831             The user's real group ID.
3833     globdot (+)
3834             If set, wild-card glob patterns will match files and directories
3835             beginning with ‘.’ except for ‘.’ and ‘..’.
3837     globstar (+)
3838             If set, the ‘**’ and ‘***’ file glob patterns will match any
3839             string of characters including ‘/’ traversing any existing sub-
3840             directories.  For example,
3841                   ls **.c
3842             will list all the .c files in the current directory tree.
3844             If used by itself, it will match zero or more sub-directories.
3845             For example,
3846                   ls /usr/include/**/time.h
3847             will list any file named ‘time.h’ in the /usr/include directory
3848             tree; whereas
3849                   ls /usr/include/**time.h
3850             will match any file in the /usr/include directory tree ending in
3851             ‘time.h’.
3853             To prevent problems with recursion, the ‘**’ glob-pattern will
3854             not descend into a symbolic link containing a directory.  To
3855             override this, use ‘***’.
3857     group (+)
3858             The user's group name.
3860     highlight
3861             If set, the incremental search match (in i-search-back and
3862             i-search-fwd) and the region between the mark and the cursor are
3863             highlighted in reverse video.
3865             Highlighting requires more frequent terminal writes, which intro‐
3866             duces extra overhead.  If you care about terminal performance,
3867             you may want to leave this unset.
3869     histchars
3870             A string value determining the characters used in History
3871             substitution.
3873             The first character of its value is used as the history substitu‐
3874             tion character, replacing the default character ‘!’.
3876             The second character of its value replaces the character ‘^’ in
3877             quick substitutions.
3879     histdup (+)
3880             Controls handling of duplicate entries in the history list.
3882             If set to ‘all’ only unique history events are entered in the
3883             history list.
3885             If set to ‘prev’ and the last history event is the same as the
3886             current command, then the current command is not entered in the
3887             history.
3889             If set to ‘erase’ and the same event is found in the history
3890             list, that old event gets erased and the current one gets in‐
3891             serted.
3893             Note that the ‘prev’ and ‘all’ options renumber history events so
3894             there are no gaps.
3896     histfile (+)
3897             The default location in which
3898                   history -S
3899             and
3900                   history -L
3901             look for a history file.
3903             If unset, ~/.history is used.
3905             histfile is useful when sharing the same home directory between
3906             different machines, or when saving separate histories on differ‐
3907             ent terminals.  Because only ~/.tcshrc is normally sourced before
3908             ~/.history, histfile should be set in ~/.tcshrc rather than
3909             ~/.login.
3911     histlit (+)
3912             If set, builtin and editor commands and the savehist mechanism
3913             use the literal (unexpanded) form of lines in the history list.
3914             See also the toggle-literal-history editor command.
3916     history
3917             The first word indicates the number of history events to save.
3919             The optional second word (+) indicates the format in which his‐
3920             tory is printed; if not given, ‘%h\t%T\t%R\n’ is used.  The for‐
3921             mat sequences are described below under prompt; note the variable
3922             meaning of ‘%R’.
3924             Set to ‘100’ by default.
3926     home    Initialized to the home directory of the invoker.  The filename
3927             expansion of ‘~’ refers to this variable.
3929     ignoreeof
3930             If set to the empty string or ‘0’ and the input device is a ter‐
3931             minal, the end-of-file command (usually generated by the user by
3932             typing ^D on an empty line) causes the shell to print
3933                   Use "exit" to leave tcsh.
3934             instead of exiting.  This prevents the shell from accidentally
3935             being killed.  Historically this setting exited after 26 succes‐
3936             sive EOF's to avoid infinite loops.
3938             If set to a number ‘n’, the shell ignores n - 1 consecutive
3939             end-of-files and exits on the nth (+).
3941             If unset, ‘1’ is used, i.e., the shell exits on a single ^D.
3943     implicitcd (+)
3944             If set, the shell treats a directory name typed as a command as
3945             though it were a request to change to that directory.
3947             If set to verbose, the change of directory is echoed to the stan‐
3948             dard output.
3950             This behavior is inhibited in non-interactive shell scripts, or
3951             for command strings with more than one word.  Changing directory
3952             takes precedence over executing a like-named command, but it is
3953             done after alias substitutions.  Tilde and variable expansions
3954             work as expected.
3956     inputmode (+)
3957             If set to ‘insert’ or ‘overwrite’, puts the editor into that in‐
3958             put mode at the beginning of each line.
3960     killdup (+)
3961             Controls handling of duplicate entries in the kill ring.
3963             If set to ‘all’ only unique strings are entered in the kill ring.
3965             If set to ‘prev’ and the last killed string is the same as the
3966             current killed string, then the current string is not entered in
3967             the ring.
3969             If set to ‘erase’ and the same string is found in the kill ring,
3970             the old string is erased and the current one is inserted.
3972     killring (+)
3973             Indicates the number of killed strings to keep in memory.
3975             Set to ‘30’ by default.
3977             If unset or set to less than ‘2’, the shell will only keep the
3978             most recently killed string.
3980             Strings are put in the killring by the editor commands that
3981             delete (kill) strings of text, e.g.  backward-delete-word,
3982             kill-line, etc, as well as the copy-region-as-kill command.  The
3983             yank editor command will yank the most recently killed string
3984             into the command-line, while yank-pop (see Editor commands (+))
3985             can be used to yank earlier killed strings.
3987     listflags (+)
3988             If set to ‘x’, ‘a’, or ‘A’, or any combination thereof (e.g.,
3989             ‘xA’), they are used as flags to ls-F, making it act like
3990                   ls -xF
3991                   ls -Fa
3992                   ls -FA
3994             or a combination, for example
3995                   ls -FxA
3997             If the first word contains ‘a’, shows all files (even if they
3998             start with a ‘.’).
4000             If the first word contains ‘A’, shows all files but ‘.’ and ‘..’.
4002             If the first word contains ‘x’, sorts across instead of down.
4004             If the second word of listflags is set, it is used as the path to
4005             ls(1).
4007     listjobs (+)
4008             If set, all jobs are listed when a job is suspended.
4010             If set to ‘long’, the listing is in long format.
4012     listlinks (+)
4013             If set, the ls-F builtin command shows the type of file to which
4014             each symbolic link points.
4016     listmax (+)
4017             The maximum number of items which the list-choices editor command
4018             will list without asking first.
4020     listmaxrows (+)
4021             The maximum number of rows of items which the list-choices editor
4022             command will list without asking first.
4024     loginsh (+)
4025             Set by the shell if it is a login shell.  Setting or unsetting it
4026             within a shell has no effect.  See also shlvl.
4028     logout (+)
4029             Set by the shell to ‘normal’ before a normal logout, ‘automatic’
4030             before an automatic logout, and ‘hangup’ if the shell was killed
4031             by a hangup signal (see Signal handling).  See also the
4032             autologout shell variable.
4034     mail    A list of files and directories to check for incoming mail, op‐
4035             tionally preceded by a numeric word.  Before each prompt, if 10
4036             minutes have passed since the last check, the shell checks each
4037             file and displays
4038                   You have new mail.
4039             (or, if mail contains multiple files,
4040                   You have new mail in name.)
4041             if the filesize is greater than zero in size and has a modifica‐
4042             tion time greater than its access time.
4044             If you are in a login shell, then no mail file is reported unless
4045             it has been modified after the time the shell has started up, to
4046             prevent redundant notifications.  Most login programs will tell
4047             you whether or not you have mail when you log in.
4049             If a file specified in mail is a directory, the shell will count
4050             each file within that directory as a separate message, and will
4051             report
4052                   You have n mails.
4053             or
4054                   You have n mails in name.
4055             as appropriate.  This functionality is provided primarily for
4056             those systems which store mail in this manner, such as the Andrew
4057             Mail System.
4059             If the first word of mail is numeric it is taken as a different
4060             mail checking interval, in seconds.
4062             Under very rare circumstances, the shell may report
4063                   You have mail.
4064             instead of
4065                   You have new mail.
4067     matchbeep (+)
4068             If set to ‘never’, completion never beeps.
4070             If set to ‘nomatch’, it beeps only when there is no match.
4072             If set to ‘ambiguous’, it beeps when there are multiple matches.
4074             If set to ‘notunique’, it beeps when there is one exact and other
4075             longer matches.
4077             If unset, ‘ambiguous’ is used.
4079     nobeep (+)
4080             If set, beeping is completely disabled.  See also visiblebell.
4082     noclobber
4083             If set, restrictions are placed on output redirection to insure
4084             that files are not accidentally destroyed and that ‘>>’ redirec‐
4085             tions refer to existing files, as described in the Input/output
4086             section.
4088             If contains ‘ask’, an interacive confirmation is presented,
4089             rather than an error.
4091             If contains ‘notempty’, ‘>’ is allowed on empty files.
4093     noding  If set, disable the printing of
4094                   DING!
4095             in the prompt time specifiers at the change of hour.
4097     noglob  If set, Filename substitution and Directory stack substitution
4098             (+) are inhibited.  This is most useful in shell scripts which do
4099             not deal with filenames, or after a list of filenames has been
4100             obtained and further expansions are not desirable.
4102     nokanji (+)
4103             If set and the shell supports Kanji (see the version shell vari‐
4104             able), it is disabled so that the meta key can be used.
4106     nonomatch
4107             If set, a Filename substitution or Directory stack substitution
4108             (+) which does not match any existing files is left untouched
4109             rather than causing an error.  It is still an error for the sub‐
4110             stitution to be malformed.  For example,
4111                   echo [
4112             still gives an error.
4114     nostat (+)
4115             A list of directories (or glob-patterns which match directories;
4116             see Filename substitution) that should not be stat(2)ed during a
4117             completion operation.  This is usually used to exclude directo‐
4118             ries which take too much time to stat(2), for example /afs.
4120     notify  If set, the shell announces job completions asynchronously.  The
4121             default is to present job completions just before printing a
4122             prompt.
4124     oid (+)
4125             The user's real organization ID.  (Domain/OS only)
4127     owd (+)
4128             The old working directory, equivalent to the ‘-’ used by cd and
4129             pushd.  See also the cwd and dirstack shell variables.
4131     padhour
4132             If set, enable the printing of padding '0' for hours, in 24 and
4133             12 hour formats.  E.g., ‘07:45:42’ versus ‘7:45:42’.
4135     parseoctal
4136             To retain compatibily with older versions numeric variables
4137             starting with 0 are not interpreted as octal.  Setting this vari‐
4138             able enables proper octal parsing.
4140     path    A list of directories in which to look for executable commands.
4142             A null word specifies the current directory.
4144             If there is no path variable then only full path names will exe‐
4145             cute.
4147             path is set by the shell at startup from the PATH environment
4148             variable or, if PATH does not exist, to a system-dependent de‐
4149             fault, such as
4150                   (/usr/local/bin /usr/bsd /bin /usr/bin .)
4152             The shell may put ‘.’ first or last in path or omit it entirely
4153             depending on how it was compiled; see the version shell variable.
4155             A shell which is given neither the -c nor the -t option hashes
4156             the contents of the directories in path after reading ~/.tcshrc
4157             and each time path is reset.
4159             If one adds a new command to a directory in path while the shell
4160             is active, one may need to do a rehash for the shell to find it.
4162     printexitvalue (+)
4163             If set and an interactive program exits with a non-zero status,
4164             the shell prints
4165                   Exit status
4167     prompt  The string which is printed before reading each command from the
4168             terminal.
4170             prompt may include any of the following formatting sequences (+),
4171             which are replaced by the given information:
4173                   Format  Prompt information
4175                   %/      The current working directory.
4177                   %~      The current working directory, but with one's home
4178                           directory represented by ‘~’ and other users' home
4179                           directories represented by ‘~user’ as per Filename
4180                           substitution.  ‘~user’ substitution happens only if
4181                           the shell has already used ‘~user’ in a pathname in
4182                           the current session.
4184                   %c[[0]n], %.[[0]n]
4185                           The trailing component of the current working di‐
4186                           rectory, or n trailing components if a digit n is
4187                           given.  If n begins with ‘0’, the number of skipped
4188                           components precede the trailing component(s) in the
4189                           format ‘/<skipped>trailing’.  If the ellipsis shell
4190                           variable is set, skipped components are represented
4191                           by an ellipsis so the whole becomes ‘...trailing’.
4192                           ‘~’ substitution is done as in ‘%~’ above, but the
4193                           ‘~’ component is ignored when counting trailing
4194                           components.
4196                   %C      Like ‘%c’, but without ‘~’ substitution.
4198                   %h, %!, !
4199                           The current history event number.
4201                   %M      The full hostname.
4203                   %m      The hostname up to the first ‘.’.
4205                   %S (%s)
4206                           Start (stop) standout mode.
4208                   %B (%b)
4209                           Start (stop) boldfacing mode.
4211                   %U (%u)
4212                           Start (stop) underline mode.
4214                   %t, %@  The time of day in 12-hour AM/PM format.
4216                   %T      Like ‘%t’, but in 24-hour format (but see the ampm
4217                           shell variable).
4219                   %p      The ‘precise’ time of day in 12-hour AM/PM format,
4220                           with seconds.
4222                   %P      Like ‘%p’, but in 24-hour format (but see the ampm
4223                           shell variable).
4225                   \c      c is parsed as in bindkey.
4227                   ^c      c is parsed as in bindkey.
4229                   %%      A single ‘%’.
4231                   %n      The user name.
4233                   %N      The effective user name.
4235                   %j      The number of jobs.
4237                   %d      The weekday in ‘Day’ format.
4239                   %D      The day in ‘dd’ format.
4241                   %w      The month in ‘Mon’ format.
4243                   %W      The month in ‘mm’ format.
4245                   %y      The year in ‘yy’ format.
4247                   %Y      The year in ‘yyyy’ format.
4249                   %l      The shell's tty.
4251                   %L      Clears from the end of the prompt to end of the
4252                           display or the end of the line.
4254                   %$      Expands the shell or environment variable name im‐
4255                           mediately after the ‘$’.
4257                   %#      ‘>’ (or the first character of the promptchars
4258                           shell variable) for normal users, ‘#’ (or the sec‐
4259                           ond character of promptchars) for the superuser.
4261                   %{string%}
4262                           Includes string as a literal escape sequence.  It
4263                           should be used only to change terminal attributes
4264                           and should not move the cursor location.  This can‐
4265                           not be the last sequence in prompt.
4267                   %?      The return code of the command executed just before
4268                           the prompt.
4270                   %R      In prompt2, the status of the parser.  In prompt3,
4271                           the corrected string.  In history, the history
4272                           string.
4274             ‘%B’, ‘%S’, ‘%U’, and ‘%{string%}’ are available in only eight-
4275             bit-clean shells; see the version shell variable.
4277             The bold, standout and underline sequences are often used to dis‐
4278             tinguish a superuser shell.  For example,
4280                   > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
4281                   tut [37] [2:54pm] [/usr/accts/sys] you rang? _
4283             If ‘%t’, ‘%@’, ‘%T’, ‘%p’, or ‘%P’ is used, and noding is not
4284             set, then print
4285                   DING!
4286             on the change of hour (i.e, ‘:00’ minutes) instead of the actual
4287             time.
4289             Set by default to ‘%# ’ in interactive shells.
4291     prompt2 (+)
4292             The string with which to prompt in while and foreach loops and
4293             after lines ending in ‘\’.  The same format sequences may be used
4294             as in prompt; note the variable meaning of ‘%R’.
4296             Set by default to ‘%R? ’ in interactive shells.
4298     prompt3 (+)
4299             The string with which to prompt when confirming automatic spell‐
4300             ing correction.  The same format sequences may be used as in
4301             prompt; note the variable meaning of ‘%R’.
4303             Set by default to ‘CORRECT>%R (y|n|e|a)? ’ in interactive shells.
4305     promptchars (+)
4306             If set (to a two-character string), the ‘%#’ formatting sequence
4307             in the prompt shell variable is replaced with the first character
4308             for normal users and the second character for the superuser.
4310     pushdtohome (+)
4311             If set, pushd without arguments does
4312                   pushd ~
4313             like cd.
4315     pushdsilent (+)
4316             If set, pushd and popd do not print the directory stack.
4318     recexact (+)
4319             If set, completion completes on an exact match even if a longer
4320             match is possible.
4322     recognize_only_executables (+)
4323             If set, command listing displays only files in the path that are
4324             executable.  Slow.
4326     rmstar (+)
4327             If set, the user is prompted before
4328                   rm *
4329             is executed.
4331     rprompt (+)
4332             The string to print on the right-hand side of the screen (after
4333             the command input) when the prompt is being displayed on the
4334             left.  It recognizes the same formatting characters as prompt.
4335             It will automatically disappear and reappear as necessary, to en‐
4336             sure that command input isn't obscured, and will appear only if
4337             the prompt, command input, and itself will fit together on the
4338             first line.
4340             If edit isn't set, then rprompt will be printed after the prompt
4341             and before the command input.
4343     savedirs (+)
4344             If set, the shell does
4345                   dirs -S
4346             before exiting.
4348             If the first word is set to a number, at most that many directory
4349             stack entries are saved.
4351     savehist
4352             If set, the shell does
4353                   history -S
4354             before exiting.
4356             If the first word is set to a number, at most that many lines are
4357             saved.  (The number should be less than or equal to the number
4358             history entries; if it is set to greater than the number of
4359             history settings, only history entries will be saved.)
4361             If the second word is set to ‘merge’, the history list is merged
4362             with the existing history file instead of replacing it (if there
4363             is one) and sorted by time stamp and the most recent events are
4364             retained.
4366             If the second word is set to ‘merge’ and the third word is set to
4367             ‘lock’, the history file update will be serialized with other
4368             shell sessions that would possibly like to merge history at ex‐
4369             actly the same time. (+)
4371     sched (+)
4372             The format in which the sched builtin command prints scheduled
4373             events; if not given, ‘%h\t%T\t%R\n’ is used.  The format se‐
4374             quences are described above under prompt; note the variable mean‐
4375             ing of ‘%R’.
4377     shell   The file in which the shell resides.  This is used in forking
4378             shells to interpret files which have execute bits set, but which
4379             are not executable by the system.  (See the description of
4380             Builtin and non-builtin command execution.)  Initialized to the
4381             (system-dependent) home of the shell.
4383     shlvl (+)
4384             The number of nested shells.  Reset to 1 in login shells.  See
4385             also loginsh.
4387     status  The exit status from the last command or backquote expansion, or
4388             any command in a pipeline is propagated to status.  (This is also
4389             the default csh(1) behavior.)  This default does not match what
4390             POSIX mandates (to return the status of the last command only).
4391             To match the POSIX behavior, you need to unset anyerror.
4393             If the anyerror variable is unset, the exit status of a pipeline
4394             is determined only from the last command in the pipeline, and the
4395             exit status of a backquote expansion is not propagated to status.
4397             If a command terminated abnormally, then 0200 is added to the
4398             status.  Builtin commands which fail return exit status ‘1’, all
4399             other builtin commands return status ‘0’.
4401     symlinks (+)
4402             Can be set to several different values to control symbolic link
4403             (‘symlink’) resolution:
4405             If set to ‘chase’, whenever the current directory changes to a
4406             directory containing a symbolic link, it is expanded to the real
4407             name of the directory to which the link points.  This does not
4408             work for the user's home directory; this is a bug.
4410             If set to ‘ignore’, the shell tries to construct a current direc‐
4411             tory relative to the current directory before the link was
4412             crossed.  This means that
4413                   cd
4414             through a symbolic link and then
4415                   cd ..
4416             returns one to the original directory.  This affects only builtin
4417             commands and filename completion.
4419             If set to ‘expand’, the shell tries to fix symbolic links by ac‐
4420             tually expanding arguments which look like path names.  This af‐
4421             fects any command, not just builtins.  Unfortunately, this does
4422             not work for hard-to-recognize filenames, such as those embedded
4423             in command options.  Expansion may be prevented by quoting.
4424             While this setting is usually the most convenient, it is some‐
4425             times misleading and sometimes confusing when it fails to recog‐
4426             nize an argument which should be expanded.  A compromise is to
4427             use ‘ignore’ and use the editor command normalize-path (bound by
4428             default to ^X-n) when necessary.
4430             Some examples are in order.  First, let's set up some play direc‐
4431             tories:
4433                   > cd /tmp
4434                   > mkdir from from/src to
4435                   > ln -s from/src to/dst
4437             Here's the behavior with symlinks unset,
4439                   > cd /tmp/to/dst; echo $cwd
4440                   /tmp/to/dst
4441                   > cd ..; echo $cwd
4442                   /tmp/from
4444             Here's the behavior with symlinks set to ‘chase’,
4446                   > cd /tmp/to/dst; echo $cwd
4447                   /tmp/from/src
4448                   > cd ..; echo $cwd
4449                   /tmp/from
4451             Here's the behavior with symlinks set to ‘ignore’,
4453                   > cd /tmp/to/dst; echo $cwd
4454                   /tmp/to/dst
4455                   > cd ..; echo $cwd
4456                   /tmp/to
4458             Here's the behavior with symlinks set to ‘expand’.
4460                   > cd /tmp/to/dst; echo $cwd
4461                   /tmp/to/dst
4462                   > cd ..; echo $cwd
4463                   /tmp/to
4464                   > cd /tmp/to/dst; echo $cwd
4465                   /tmp/to/dst
4466                   > cd ".."; echo $cwd
4467                   /tmp/from
4468                   > /bin/echo ..
4469                   /tmp/to
4470                   > /bin/echo ".."
4471                   ..
4473             Note that ‘expand’ expansion:
4474                   1.   Works just like ‘ignore’ for builtins like cd.
4475                   2.   Is prevented by quoting.
4476                   3.   Happens before filenames are passed to non-builtin
4477                        commands.
4479     tcsh (+)
4480             The version number of the shell in the format ‘R.VV.PP’, where
4481R’ is the major release number, ‘VV’ the current version, and
4482PP’ the patchlevel.
4484     term    The terminal type.  Usually set in ~/.login as described under
4485             Startup and shutdown.
4487     time    If set to a number, then the time builtin executes automatically
4488             after each command which takes more than that many CPU seconds.
4490             If there is a second word, it is used as a format string for the
4491             output of the time builtin.
4493             (u) The following sequences may be used in the time format
4494             string:
4496                   Format  Time information
4498                   %U      The time the process spent in user mode in cpu sec‐
4499                           onds.
4501                   %S      The time the process spent in kernel mode in cpu
4502                           seconds.
4504                   %E      The elapsed (wall clock) time in seconds.
4506                   %P      The CPU percentage computed as (%U + %S) / %E.
4508                   %W      Number of times the process was swapped.
4510                   %X      The average amount in (shared) text space used in
4511                           Kbytes.
4513                   %D      The average amount in (unshared) data/stack space
4514                           used in Kbytes.
4516                   %K      The total space used (%X + %D) in Kbytes.
4518                   %M      The maximum memory the process had in use at any
4519                           time in Kbytes.
4521                   %F      The number of major page faults (page needed to be
4522                           brought from disk).
4524                   %R      The number of minor page faults.
4526                   %I      The number of input operations.
4528                   %O      The number of output operations.
4530                   %r      The number of socket messages received.
4532                   %s      The number of socket messages sent.
4534                   %k      The number of signals received.
4536                   %w      The number of voluntary context switches (waits).
4538                   %c      The number of involuntary context switches.
4540             Only the first four sequences are supported on systems without
4541             BSD resource limit functions.  The default time format is ‘%Uu
4542             %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww’ for systems that support re‐
4543             source usage reporting and ‘%Uu %Ss %E %P’ for systems that do
4544             not.
4546             Under Sequent's DYNIX/ptx, ‘%X’, ‘%D’, ‘%K’, ‘%r’, and ‘%s’ are
4547             not available, but the following additional sequences are:
4549                   Format  Description Sequent DYNIX/ptx time information
4551                   %Y      The number of system calls performed.
4553                   %Z      The number of pages which are zero-filled on de‐
4554                           mand.
4556                   %i      The number of times a process's resident set size
4557                           was increased by the kernel.
4559                   %d      The number of times a process's resident set size
4560                           was decreased by the kernel.
4562                   %l      The number of read system calls performed.
4564                   %m      The number of write system calls performed.
4566                   %p      The number of reads from raw disk devices.
4568                   %q      The number of writes to raw disk devices.
4570             and the default time format is ‘%Uu %Ss %E %P %I+%Oio %Fpf+%Ww’.
4572             Note that the CPU percentage can be higher than 100% on multi-
4573             processors.
4575     tperiod (+)
4576             The period, in minutes, between executions of the periodic spe‐
4577             cial alias.
4579     tty (+)
4580             The name of the tty, or empty if not attached to one.
4582     uid (+)
4583             The user's real user ID.
4585     user    The user's login name.
4587     verbose
4588             If set, causes the words of each command to be printed, after
4589             history substitution (if any).  Set by the -v command line op‐
4590             tion.
4592     version (+)
4593             The version ID stamp.  It contains the shell's version number
4594             (see tcsh), origin, release date, vendor, operating system and
4595             machine (see VENDOR, OSTYPE, and MACHTYPE) and a comma-separated
4596             list of options which were set at compile time.  Options which
4597             are set by default in the distribution are noted.
4599             Supported version options include:
4601                   Option  Description
4603                   8b      The shell is eight bit clean; default.
4605                   7b      The shell is not eight bit clean.
4607                   wide    The shell is multi-byte encoding clean (like
4608                           UTF-8).
4610                   nls     The system's NLS is used; default for systems with
4611                           NLS.
4613                   lf      Login shells execute /etc/csh.login before instead
4614                           of after /etc/csh.cshrc and ~/.login before instead
4615                           of after ~/.tcshrc and ~/.history.
4617                   dl      ‘.’ is put last in path for security; default.
4619                   nd      ‘.’ is omitted from path for security.
4621                   vi      vi(1)-style editing is the default rather than
4622                           emacs(1)-style.
4624                   dtr     Login shells drop DTR when exiting.
4626                   bye     bye is a synonym for logout and log is an alternate
4627                           name for watchlog.
4629                   al      autologout is enabled; default.
4631                   kan     Kanji is used if appropriate according to locale
4632                           settings, unless the nokanji shell variable is set.
4634                   sm      The system's malloc(3) is used.
4636                   hb      The
4637                                 #!interpreter arg ...
4638                           convention is emulated when executing shell
4639                           scripts.
4641                   ng      The newgrp builtin is available.
4643                   rh      The shell attempts to set the REMOTEHOST environ‐
4644                           ment variable.
4646                   afs     The shell verifies your password with the kerberos
4647                           server if local authentication fails.  The afsuser
4648                           shell variable or the AFSUSER environment variable
4649                           override your local username if set.
4651             An administrator may enter additional strings to indicate differ‐
4652             ences in the local version.
4654     vimode (+)
4655             If unset, various key bindings change behavior to be more
4656             emacs(1)-style: word boundaries are determined by wordchars ver‐
4657             sus other characters.
4659             If set, various key bindings change behavior to be more
4660             vi(1)-style: word boundaries are determined by wordchars versus
4661             whitespace versus other characters; cursor behavior depends upon
4662             current vi mode (command, delete, insert, replace).
4664             This variable is unset by bindkey -e and set by bindkey -v.
4665             vimode may be explicitly set or unset by the user after those
4666             bindkey operations if required.
4668     visiblebell (+)
4669             If set, a screen flash is used rather than the audible bell.  See
4670             also nobeep.
4672     watch (+)
4673             A list of user/terminal pairs to watch for logins and logouts.
4674             If either the user is ‘any’ all terminals are watched for the
4675             given user and vice versa.  Setting watch to
4676                   (any any)
4677             watches all users and terminals.  For example,
4679                   set watch = (george ttyd1 any console $user any)
4681             reports activity of the user ‘george’ on ‘ttyd1’, any user on the
4682             console, and oneself (or a trespasser) on any terminal.
4684             Logins and logouts are checked every 10 minutes by default, but
4685             the first word of watch can be set to a number to check every so
4686             many minutes.  For example,
4688                   set watch = (1 any any)
4690             reports any login/logout once every minute.  For the impatient,
4691             the log builtin command triggers a watch report at any time.  All
4692             current logins are reported (as with the log builtin) when watch
4693             is first set.
4695             The who shell variable controls the format of watch reports.
4697     who (+)
4698             The format string for watch messages.  The following sequences
4699             are replaced by the given information:
4701                   Format  Who information
4703                   %n      The name of the user who logged in/out.
4705                   %a      The observed action, i.e., ‘logged on’, ‘logged
4706                           off’, or ‘replaced olduser on’.
4708                   %l      The terminal (tty) on which the user logged in/out.
4710                   %M      The full hostname of the remote host, or ‘local’ if
4711                           the login/logout was from the local host.
4713                   %m      The hostname of the remote host up to the first
4714                           ‘.’.  The full name is printed if it is an IP ad‐
4715                           dress or an X Window System display.
4717             ‘%M’ and ‘%m’ are available on only systems that store the remote
4718             hostname in /etc/utmp.
4720             If unset,
4721                   %n has %a %l from %m.
4722             is used, or
4723                   %n has %a %l.
4724             on systems which don't store the remote hostname.
4726     wordchars (+)
4727             A list of non-alphanumeric characters to be considered part of a
4728             word by the forward-word, backward-word, etc., editor commands.
4730             If unset, the default value is determined based on the state of
4731             vimode: if vimode is unset, ‘*?_-.[]~=’ is used as the default;
4732             if vimode is set, ‘_’ is used as the default.


4735     AFSUSER (+)
4736             Equivalent to the afsuser shell variable.
4739             Color sequences for ls-F are normally disabled if the output is
4740             not directed to a terminal.  This can be overridden by setting
4741             this variable, which also changes the ls-F invocation of ls(1) to
4742             use --color=always instead of --color=auto.
4744             Note that color must be set for this environment variable to be
4745             effective; by itself CLICOLOR_FORCE does not enable color ls-F.
4748             Set by tcsh to the current command line when invoking programs
4749             for the complete list mode ‘`...`’.  See complete in Builtin
4750             commands.
4752     COLUMNS
4753             The number of columns in the terminal.  See Terminal management
4754             (+).
4756     DISPLAY
4757             Used by X Window System (see X(1)).  If set, the shell does not
4758             set autologout.
4760     EDITOR  The pathname to a default editor.  Used by the run-fg-editor edi‐
4761             tor command if the the editors shell variable is unset.  See also
4762             the VISUAL environment variable.
4764     GROUP (+)
4765             Equivalent to the group shell variable.
4767     HOME    Equivalent to the home shell variable.
4769     HOST (+)
4770             Initialized to the name of the machine on which the shell is run‐
4771             ning, as determined by the gethostname(2) system call.
4773     HOSTTYPE (+)
4774             Initialized to the type of machine on which the shell is running,
4775             as determined at compile time.  This variable is obsolete and
4776             will be removed in a future version.
4778     HPATH (+)
4779             A ‘:’-separated list of directories in which the run-help editor
4780             command looks for command documentation.
4782     LANG    Gives the preferred character environment.  See Native Language
4783             System support (+).
4785     LC_CTYPE
4786             If set, only ctype character handling is changed.  See Native
4787             Language System support (+).
4789     LINES   The number of lines in the terminal.  See Terminal management
4790             (+).
4792     LSCOLORS
4793             One of two environment variables that may be used to define the
4794             per-file colors used by ls-F (along with LS_COLORS).  This vari‐
4795             able is used by some BSD versions of ls(1).
4797             On tcsh startup, LS_COLORS takes priority over LSCOLORS.  If both
4798             LSCOLORS or LS_COLORS are setenv, the most recent setenv is used.
4799             If LSCOLORS is unsetenv while LS_COLORS is still setenv, then
4800             LS_COLORS is parsed again (with any warnings suppressed) to reap‐
4801             ply its settings.
4803             This variable is a 22 character string containing a concatenation
4804             of 11 pairs of the format fb, where f is the foreground color and
4805             b is the background color.  If fewer than 11 pairs are provided,
4806             default colors are used for the remaining entries.  If more than
4807             11 pairs are provided, the extra values are ignored.
4809             The order of the color attribute pairs to the equivalent
4810             LS_COLORS variable, the file type, and default color, is as fol‐
4811             lows:
4813                   Index    Var    File type. [Default color]
4814                   1        di     Directory. [Bold blue]
4815                   2        ln     Symbolic link. [Bold cyan]
4816                   3        so     Socket. [Bold magenta]
4817                   4        pi     Named pipe (FIFO). [Yellow (or brown)]
4818                   5        ex     Executable file. [Bold green]
4819                   6        bd     Block device. [Bold yellow]
4820                   7        cd     Character device. [Bold yellow]
4821                   8        su     Setuid file. [White on red]
4822                   9        sg     Setgid file. [Black on yellow]
4823                   10       tw     Sticky and other writable directory. [Black
4824                                       on green]
4825                   11       ow     Other writable but not sticky directory.
4826                                       [Blue on green]
4828             The color code designators are as follows:
4830                   Code  Description
4831                   a     Black.
4832                   b     Red.
4833                   c     Green.
4834                   d     Yellow (or brown).
4835                   e     Blue.
4836                   f     Magenta.
4837                   g     Cyan.
4838                   h     Light grey.
4839                   A     Bold black, usually shows up as dark grey.
4840                   B     Bold red.
4841                   C     Bold green.
4842                   D     Bold yellow.
4843                   E     Bold blue.
4844                   F     Bold magenta.
4845                   G     Bold cyan.
4846                   H     Bold light grey; looks like bright white.
4847                   x     Default foreground or background.
4849             Note that the above are standard ANSI colors.  The actual display
4850             may differ depending on the color capabilities of the terminal in
4851             use.
4853             The default colors are as per the color variables in LS_COLORS,
4854             and are not the same default colors as those used by some BSD
4855             versions of ls(1).
4857     LS_COLORS
4858             One of two environment variables that may be used to define the
4859             per-file colors used by ls-F (along with LSCOLORS).  This vari‐
4860             able is used by the GNU coreutils version of ls(1) and may be
4861             setup by dircolors(1).
4863             On tcsh startup, LS_COLORS takes priority over LSCOLORS.  If both
4864             LSCOLORS or LS_COLORS are setenv, the most recent setenv is used.
4865             If LS_COLORS is unsetenv while LSCOLORS is still setenv, then
4866             LSCOLORS is parsed again (with any warnings suppressed) to reap‐
4867             ply its settings.
4869             The format of this variable is reminiscent of the termcap(5) file
4870             format; a ‘:’-separated list of expressions of the form
4871             "xx=value" or "*ext=value".
4873             The first form "xx=value", where "xx" is a two-character variable
4874             name, supports the following variables, their associated default
4875             ISO 6429 color code or escape sequences, and file type:
4877                   Var    Default    File type. [Default color]
4878                   no     0          Normal (non-filename) text.
4879                   fi     0          Regular file.
4880                   di     01;34      Directory. [Bold blue]
4881                   ln     01;36      Symbolic link. [Bold cyan]
4882                   pi     33         Named pipe (FIFO). [Yellow (or brown)]
4883                   so     01;35      Socket. [Bold magenta]
4884                   do     01;35      Door. [Bold magenta]
4885                   bd     01;33      Block device. [Bold yellow]
4886                   cd     01;33      Character device. [Bold yellow]
4887                   ex     01;32      Executable file. [Bold green]
4888                   mi     (none)     Missing file (orphaned symbolic link
4889                                         target). Defaults to fi.
4890                   or     (none)     Orphaned (broken) symbolic link. Defaults
4891                                         to ln.
4892                   lc     ^[[        Left code.
4893                   rc     m          Right code.
4894                   ec     (none)     End code. Replaces lc+no+rc.
4895                   su     37;41      Setuid file. [White on red]
4896                   sg     30;43      Setgid file. [Black on yellow]
4897                   tw     30;42      Sticky and other writable directory.
4898                                         [Black on green]
4899                   ow     34;42      Other writable but not sticky directory.
4900                                         [Blue on green]
4901                   st     37;44      Sticky but not other writable directory.
4902                                         [White on blue]
4903                   mh     (none)     File with multiple hard links.
4905             You need to include only the variables you want to change from
4906             the default.
4908             The second form "*ext=value" colorizes file names based on exten‐
4909             sion.  For example, using ISO 6429 codes, to color all C-language
4910             source files blue you would specify "*.c=34".  This would color
4911             all files ending in ‘.c’ in blue foreground (34) color.
4913             Control characters can be written either in C-style-escaped nota‐
4914             tion, or in stty-like ^-notation.  The C-style notation adds ‘^[’
4915             for Escape, ‘_’ for a normal space character, and ‘?’ for Delete.
4916             In addition, the ‘^[’ escape character can be used to override
4917             the default interpretation of ‘^[’, ‘^’, ‘:’, and ‘=’.
4919             Each filename will be output to the terminal as
4920                   lc color-code rc filename ec
4922             If the ‘ec’ code is undefined, the sequence
4923                   lc no rc
4924             will be used instead.  This is generally more convenient to use,
4925             but less general.
4927             The left code (‘lc’), right code (‘rc’), and end codes (‘ec’) are
4928             provided so you don't have to type common parts over and over
4929             again and to support weird terminals; you will generally not need
4930             to change them at all unless your terminal does not use ISO 6429
4931             color codes but a different system.
4933             If your terminal uses ISO 6429 color codes, you can compose the
4934             type codes (i.e., all except the ‘lc’, ‘rc’, and ‘ec’ codes) from
4935             numerical ISO 6429 color codes separated by ‘;’.  For example,
4936             ‘01;32’ is bright green foreground with default background.
4938             The most common ISO 6429 color codes are:
4940                   Color  Description
4942                   0      To restore default color.
4943                   1      Bold / brighter colors.
4944                   4      Underlined text.
4945                   5      Flashing text.
4946                   30     Black foreground.
4947                   31     Red foreground.
4948                   32     Green foreground.
4949                   33     Yellow (or brown) foreground.
4950                   34     Blue foreground.
4951                   35     Magenta foreground.
4952                   36     Cyan foreground.
4953                   37     White (or gray) foreground.
4954                   40     Black background.
4955                   41     Red background.
4956                   42     Green background.
4957                   43     Yellow (or brown) background.
4958                   44     Blue background.
4959                   45     Magenta background.
4960                   46     Cyan background.
4961                   47     White (or gray) background.
4963             Not all ISO 6429 color codes will work on all systems or display
4964             devices.
4966             A few terminal programs do not recognize the default end code
4967             properly.  If all text gets colorized after you do a directory
4968             listing, try changing the ‘no’ and ‘fi’ codes from 0 to the nu‐
4969             merical codes for your standard foreground and background colors.
4971             For symbolic links the ‘ln’ keyword can be set to ‘target’, which
4972             makes the file color the same as the color of the link target.
4974     MACHTYPE (+)
4975             The machine type (microprocessor class or machine model), as de‐
4976             termined at compile time.
4978     NOREBIND (+)
4979             If set, printable characters are not rebound to
4980             self-insert-command.  See Native Language System support (+).
4982     OSTYPE (+)
4983             The operating system, as determined at compile time.
4985     PATH    A ‘:’-separated list of directories in which to look for executa‐
4986             bles.  Equivalent to the path shell variable, but in a different
4987             format.
4989     PWD (+)
4990             Equivalent to the cwd shell variable, but not synchronized to it;
4991             updated only after an actual directory change.
4993     REMOTEHOST (+)
4994             The host from which the user has logged in remotely, if this is
4995             the case and the shell is able to determine it.  Set only if the
4996             shell was so compiled; see the version shell variable.
4998     SHLVL (+)
4999             Equivalent to the shlvl shell variable.
5001     SYSTYPE (+)
5002             The current system type.  (Domain/OS only)
5004     TERM    Equivalent to the term shell variable.
5006     TERMCAP
5007             The terminal capability string.  See Terminal management (+).
5009     USER    Equivalent to the user shell variable.
5011     VENDOR (+)
5012             The vendor, as determined at compile time.
5014     VISUAL  The pathname to a default full-screen editor.  Used by the
5015             run-fg-editor editor command if the the editors shell variable is
5016             unset.  See also the EDITOR environment variable.


5019     /etc/csh.cshrc
5020             Read first by every shell.
5022             ConvexOS, Stellix and Intel use /etc/cshrc.
5024             NeXTs use /etc/cshrc.std.
5026             A/UX, AMIX, Cray and IRIX have no equivalent in csh(1), but read
5027             this file in tcsh anyway.
5029             Solaris 2.x does not have it either, but tcsh reads /etc/.cshrc.
5031             (+)
5033     /etc/csh.login
5034             Read by login shells after /etc/csh.cshrc.
5036             ConvexOS, Stellix and Intel use /etc/login.
5038             NeXTs use /etc/login.std.
5040             Solaris 2.x uses /etc/.login.
5042             A/UX, AMIX, Cray and IRIX use /etc/cshrc.
5044     ~/.tcshrc (+)
5045             Read by every shell after /etc/csh.cshrc or its equivalent.
5047     ~/.cshrc
5048             Read by every shell, if ~/.tcshrc doesn't exist, after
5049             /etc/csh.cshrc or its equivalent.
5051             This manual uses ‘~/.tcshrc’ to mean “~/.tcshrc or, if ~/.tcshrc
5052             is not found, ~/.cshrc”.
5054     ~/.history
5055             Read by login shells after ~/.tcshrc if savehist is set, but see
5056             also histfile.
5058     ~/.login
5059             Read by login shells after ~/.tcshrc or ~/.history.
5061             The shell may be compiled to read ~/.login before instead of af‐
5062             ter ~/.tcshrc and ~/.history; see the version shell variable.
5064     ~/.cshdirs (+)
5065             Read by login shells after ~/.login if savedirs is set, but see
5066             also dirsfile.
5068     /etc/csh.logout
5069             Read by login shells at logout.
5071             ConvexOS, Stellix and Intel use /etc/logout.  NeXTs use
5072             /etc/logout.std.
5074             A/UX, AMIX, Cray and IRIX have no equivalent in csh(1), but read
5075             this file in tcsh anyway.
5077             Solaris 2.x does not have it either, but tcsh reads /etc/.logout.
5078             (+)
5080     ~/.logout
5081             Read by login shells at logout after /etc/csh.logout or its
5082             equivalent.
5084     /bin/sh
5085             Used to interpret shell scripts not starting with a ‘#’.
5087     /tmp/sh*
5088             Temporary file for ‘<<’.
5090     /etc/passwd
5091             Source of home directories for ‘~name’ substitutions.
5093     The order in which startup files are read may differ if the shell was so
5094     compiled; see Startup and shutdown and the version shell variable.


5097     This manual describes tcsh as a single entity, but experienced csh(1)
5098     users will want to pay special attention to tcsh's new features.
5100     A command-line editor, which supports emacs(1)-style or vi(1)-style key
5101     bindings.  See The command-line editor (+) and Editor commands (+).
5103     Programmable, interactive word completion and listing.  See Completion
5104     and listing (+) and the complete and uncomplete builtin commands.
5106     Spelling correction (+) of filenames, commands and variables.
5108     Editor commands (+) which perform other useful functions in the middle of
5109     typed commands, including documentation lookup (run-help), quick editor
5110     restarting (run-fg-editor), and command resolution (which-command).
5112     An enhanced history mechanism.  Events in the history list are time-
5113     stamped.  See also the history command and its associated shell vari‐
5114     ables, the previously undocumented ‘#’ event specifier and new modifiers
5115     under History substitution, the down-history, expand-history,
5116     history-search-backward, history-search-forward, i-search-back,
5117     i-search-fwd, toggle-literal-history, vi-search-back, vi-search-fwd, and
5118     up-history editor commands and the histlit shell variable.
5120     Enhanced directory parsing and directory stack handling.  See the cd,
5121     pushd, popd, and dirs commands and their associated shell variables, the
5122     description of Directory stack substitution (+), the dirstack, owd, and
5123     symlinks shell variables and the normalize-command and normalize-path ed‐
5124     itor commands.
5126     Negation in glob-patterns.  See Filename substitution.
5128     New File inquiry operators and a filetest builtin which uses them.
5130     A variety of Automatic, periodic and timed events (+) including scheduled
5131     events, special aliases, automatic logout and terminal locking, command
5132     timing and watching for logins and logouts.
5134     Support for the Native Language System (see Native Language System
5135     support (+)), OS variant features (see OS variant support (+) and the
5136     echo_style shell variable) and system-dependent file locations (see
5137     FILES).
5139     Extensive terminal-management capabilities.  See Terminal management (+).
5141     New builtin commands including builtins, hup, ls-F, newgrp, printenv,
5142     which, and where.
5144     New variables that make useful information easily available to the shell.
5145     See the gid, loginsh, oid, shlvl, tcsh, tty, uid, and version shell vari‐
5146     ables and the HOST, REMOTEHOST, VENDOR, OSTYPE, and MACHTYPE environment
5147     variables.
5149     A new syntax for including useful information in the prompt string (see
5150     prompt), and special prompts for loops and spelling correction (see
5151     prompt2 and prompt3).
5153     Read-only variables.  See Variable substitution.


5156     In 1964, DEC produced the PDP-6.  The PDP-10 was a later re-implementa‐
5157     tion.  It was re-christened the DECsystem-10 in 1970 or so when DEC
5158     brought out the second model, the KI10.
5160     TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts
5161     think tank) in 1972 as an experiment in demand-paged virtual memory oper‐
5162     ating systems.  They built a new pager for the DEC PDP-10 and created the
5163     OS to go with it.  It was extremely successful in academia.
5165     In 1975, DEC brought out a new model of the PDP-10, the KL10; they in‐
5166     tended to have only a version of TENEX, which they had licensed from BBN,
5167     for the new box.  They called their version TOPS-20 (their capitalization
5168     is trademarked).  A lot of TOPS-10 users (`The OPerating System for
5169     PDP-10') objected; thus DEC found themselves supporting two incompatible
5170     systems on the same hardware--but then there were 6 on the PDP-11!
5172     TENEX, and TOPS-20 to version 3, had command completion via a user-code-
5173     level subroutine library called ULTCMD.  With version 3, DEC moved all
5174     that capability and more into the monitor (`kernel' for you Unix types),
5175     accessed by the COMND% JSYS (`Jump to SYStem' instruction, the supervisor
5176     call mechanism [are my IBM roots also showing?]).
5178     The creator of tcsh was impressed by this feature and several others of
5179     TENEX and TOPS-20, and created a version of csh which mimicked them.


5182     The system limits argument lists to ARG_MAX characters.
5184     The number of arguments to a command which involves filename expansion is
5185     limited to 1/6th the number of characters allowed in an argument list.
5187     Command substitutions may substitute no more characters than are allowed
5188     in an argument list.
5190     To detect looping, the shell restricts the number of alias substitutions
5191     on a single line to 20.


5194     csh(1), dircolors(1), emacs(1), ls(1), newgrp(1), setpath(1), sh(1),
5195     stty(1), su(1), tset(1), vi(1), x(1), access(2), execve(2), fork(2),
5196     killpg(2), pipe(2), setrlimit(2), sigvec(2), stat(2), umask(2), vfork(2),
5197     wait(2), malloc(3), setlocale(3), tty(4), a.out(5), termcap(5),
5198     environ(7), termio(7), Introduction to the C Shell


5201     This manual documents tcsh 6.24.10 (Astron) 2023-04-14.


5204     William Joy.
5205         Original author of csh(1).
5206     J.E. Kulp, IIASA, Laxenburg, Austria.
5207         Job control and directory stack features.
5208     Ken Greer, HP Labs, 1981.
5209         File name completion.
5210     Mike Ellis, Fairchild, 1983.
5211         Command name recognition/completion.
5212     Paul Placeway, Ohio State CIS Dept., 1983-1993.
5213         Command line editor, prompt routines, new glob syntax and numerous
5214         fixes and speedups.
5215     Karl Kleinpaste, CCI, 1983-4.
5216         Special aliases, directory stack extraction stuff, login/logout
5217         watch, scheduled events, and the idea of the new prompt format.
5218     Rayan Zachariassen, University of Toronto, 1984.
5219         ls-F and which builtins and numerous bug fixes, modifications and
5220         speedups.
5221     Chris Kingsley, Caltech.
5222         Fast storage allocator routines.
5223     Chris Grevstad, TRW, 1987.
5224         Incorporated 4.3BSD csh(1) into tcsh.
5225     Christos S. Zoulas, Cornell U. EE Dept., 1987-94.
5226         Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c,
5227         SHORT_STRINGS support and a new version of sh.glob.c.
5228     James J Dempsey, BBN, and Paul Placeway, OSU, 1988.
5229         A/UX port.
5230     Daniel Long, NNSC, 1988.
5231         wordchars.
5232     Patrick Wolfe, Kuck and Associates, Inc., 1988.
5233         vi mode cleanup.
5234     David C Lawrence, Rensselaer Polytechnic Institute, 1989.
5235         autolist and ambiguous completion listing.
5236     Alec Wolman, DEC, 1989.
5237         Newlines in the prompt.
5238     Matt Landau, BBN, 1989.
5239         ~/.tcshrc.
5240     Ray Moody, Purdue Physics, 1989.
5241         Magic space bar history expansion.
5242     Mordechai ????, Intel, 1989.
5243         printprompt() fixes and additions.
5244     Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989.
5245         Automatic spelling correction and prompt3.
5246     Per Hedeland, Ellemtel, Sweden, 1990-.
5247         Various bugfixes, improvements and manual updates.
5248     Hans J. Albertsson, Sun Sweden.
5249         ampm, settc, and telltc.
5250     Michael Bloom.
5251         Interrupt handling fixes.
5252     Michael Fine, Digital Equipment Corp.
5253         Extended key support.
5254     Eric Schnoebelen, Convex, 1990.
5255         Convex support, lots of csh(1) bug fixes, save and restore of direc‐
5256         tory stack.
5257     Ron Flax, Apple, 1990.
5258         A/UX 2.0 (re)port.
5259     Dan Oscarsson, LTH Sweden, 1990.
5260         NLS support and simulated NLS support for non NLS sites, fixes.
5261     Johan Widen, SICS Sweden, 1990.
5262         shlvl, Mach support, correct-line, 8-bit printing.
5263     Matt Day, Sanyo Icon, 1990.
5264         POSIX termio support, SysV limit fixes.
5265     Jaap Vermeulen, Sequent, 1990-91.
5266         Vi mode fixes, expand-line, window change fixes, Symmetry port.
5267     Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991.
5268         autolist beeping options, modified the history search to search for
5269         the whole string from the beginning of the line to the cursor.
5270     Scott Krotz, Motorola, 1991.
5271         Minix port.
5272     David Dawes, Sydney U. Australia, Physics Dept., 1991.
5273         SVR4 job control fixes.
5274     Kimmo Suominen, 1991-.
5275         Various portability and other fixes.  Added ‘$''’ (dollar-single-
5277     Jose Sousa, Interactive Systems Corp., 1991.
5278         Extended vi fixes and vi delete command.
5279     Marc Horowitz, MIT, 1991.
5280         ANSIfication fixes, new exec hashing code, imake fixes, where.
5281     Luke Mewburn, 1991-.
5282         Enhanced directory printing in prompt.  Added ellipsis and rprompt.
5283         vimode improvements.  Manual page improvements.
5284     Bruce Sterling Woodcock, sterling@netcom.com, 1991-1995.
5285         ETA and Pyramid port, Makefile and lint fixes, ignoreeof=n addition,
5286         and various other portability changes and bug fixes.
5287     Jeff Fink, 1992.
5288         complete-word-fwd and complete-word-back.
5289     Harry C. Pulley, 1992.
5290         Coherent port.
5291     Andy Phillips, Mullard Space Science Lab U.K., 1992.
5292         VMS-POSIX port.
5293     Beto Appleton, IBM Corp., 1992.
5294         Walking process group fixes, csh(1) bug fixes, POSIX file tests,
5295         POSIX SIGHUP.
5296     Scott Bolte, Cray Computer Corp., 1992.
5297         CSOS port.
5298     Kaveh R. Ghazi, Rutgers University, 1992.
5299         Tek, m88k, Titan and Masscomp ports and fixes.  Added autoconf sup‐
5300         port.
5301     Mark Linderman, Cornell University, 1992.
5302         OS/2 port.
5303     Mika Liljeberg, liljeber@kruuna.Helsinki.FI, 1992.
5304         Linux port.
5305     Tim P. Starrin, NASA Langley Research Center Operations, 1993.
5306         Read-only variables.
5307     Dave Schweisguth, Yale University, 1993-4.
5308         New man page and tcsh.man2html.
5309     Larry Schwimmer, Stanford University, 1993.
5310         AFS and HESIOD patches.
5311     Edward Hutchins, Silicon Graphics Inc., 1996.
5312         Added implicit cd.
5313     Martin Kraemer, 1997.
5314         Ported to Siemens Nixdorf EBCDIC machine.
5315     Amol Deshpande, Microsoft, 1997.
5316         Ported to WIN32 (Windows/95 and Windows/NT); wrote all the missing
5317         library and message catalog code to interface to Windows.
5318     Taga Nayuta, 1998.
5319         Color ls additions.


5322     Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig,
5323     Diana Smetters, Bob Sutterfield, Mark Verber, Elizabeth Zwicky and all
5324     the other people at Ohio State for suggestions and encouragement
5326     All the people on the net, for putting up with, reporting bugs in, and
5327     suggesting new additions to each and every version
5329     Richard M. Alderson III, for writing the T in tcsh section


5332     When a suspended command is restarted, the shell prints the directory it
5333     started in if this is different from the current directory.  This can be
5334     misleading (i.e., wrong) as the job may have changed directories inter‐
5335     nally.
5337     Shell builtin functions are not stoppable/restartable.  Command sequences
5338     of the form
5339           a ; b ; c
5340     are also not handled gracefully when stopping is attempted.  If you sus‐
5341     pend ‘b’, the shell will then immediately execute ‘c’.  This is espe‐
5342     cially noticeable if this expansion results from an alias.  It suffices
5343     to place the sequence of commands in ‘()’'s to force it to a subshell,
5344     i.e.,
5345           ( a ; b ; c )
5347     Control over tty output after processes are started is primitive; perhaps
5348     this will inspire someone to work on a good virtual terminal interface.
5349     In a virtual terminal interface much more interesting things could be
5350     done with output control.
5352     Alias substitution is most often used to clumsily simulate shell proce‐
5353     dures; shell procedures should be provided rather than aliases.
5355     Control structures should be parsed rather than being recognized as
5356     built-in commands.  This would allow control commands to be placed any‐
5357     where, to be combined with ‘|’, and to be used with ‘&’ and ‘;’ metasyn‐
5358     tax.
5360     foreach doesn't ignore here documents when looking for its end.
5362     It should be possible to use the ‘:’ modifiers on the output of command
5363     substitutions.
5365     The screen update for lines longer than the screen width is very poor if
5366     the terminal cannot move the cursor up (i.e., terminal type ‘dumb’).
5368     HPATH and NOREBIND don't need to be environment variables.
5370     Glob-patterns which do not use ‘?’, ‘*’, or ‘[]’, or which use ‘{}’ or
5371     ‘~’ are not negated correctly.
5373     The single-command form of if does output redirection even if the expres‐
5374     sion is false and the command is not executed.
5376     ls-F includes file identification characters when sorting filenames and
5377     does not handle control characters in filenames well.  It cannot be in‐
5378     terrupted.
5380     Command substitution supports multiple commands and conditions, but not
5381     cycles or backward gotos.
5383     Report bugs at https://bugs.astron.com/ preferably with fixes.  If you
5384     want to help maintain and test tcsh, add yourself to the mailing list in
5385     https://mailman.astron.com/mailman/listinfo/tcsh
5387Astron 6.24.10                  April 14, 2023                  Astron 6.24.10