1LESS(1)                     General Commands Manual                    LESS(1)
2
3
4

NAME

6       less - opposite of more
7

SYNOPSIS

9       less -?
10       less --help
11       less -V
12       less --version
13       less [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
14            [-b space] [-h lines] [-j line] [-k keyfile]
15            [-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
16            [-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
17            [-# shift] [+[+]cmd] [--] [filename]...
18       (See  the  OPTIONS section for alternate option syntax with long option
19       names.)
20
21

DESCRIPTION

23       Less is a program similar to more (1), but which allows backward  move‐
24       ment in the file as well as forward movement.  Also, less does not have
25       to read the entire input file before  starting,  so  with  large  input
26       files  it  starts  up  faster than text editors like vi (1).  Less uses
27       termcap (or terminfo on some systems), so it can run on  a  variety  of
28       terminals.   There is even limited support for hardcopy terminals.  (On
29       a hardcopy terminal, lines which should be printed at the  top  of  the
30       screen are prefixed with a caret.)
31
32       Commands  are based on both more and vi.  Commands may be preceded by a
33       decimal number, called N in the descriptions below.  The number is used
34       by some commands, as indicated.
35
36

COMMANDS

38       In  the following descriptions, ^X means control-X.  ESC stands for the
39       ESCAPE  key;  for  example  ESC-v  means  the  two  character  sequence
40       "ESCAPE", then "v".
41
42       h or H Help:  display  a  summary of these commands.  If you forget all
43              the other commands, remember this one.
44
45       SPACE or ^V or f or ^F
46              Scroll forward N  lines,  default  one  window  (see  option  -z
47              below).   If  N  is  more  than  the screen size, only the final
48              screenful is displayed.  Warning: some systems use ^V as a  spe‐
49              cial literalization character.
50
51       z      Like  SPACE,  but  if  N is specified, it becomes the new window
52              size.
53
54       ESC-SPACE
55              Like SPACE, but scrolls a full screenful,  even  if  it  reaches
56              end-of-file in the process.
57
58       ENTER or RETURN or ^N or e or ^E or j or ^J
59              Scroll  forward N lines, default 1.  The entire N lines are dis‐
60              played, even if N is more than the screen size.
61
62       d or ^D
63              Scroll forward N lines, default one half of the screen size.  If
64              N  is specified, it becomes the new default for subsequent d and
65              u commands.
66
67       b or ^B or ESC-v
68              Scroll backward N lines,  default  one  window  (see  option  -z
69              below).   If  N  is  more  than  the screen size, only the final
70              screenful is displayed.
71
72       w      Like ESC-v, but if N is specified, it  becomes  the  new  window
73              size.
74
75       y or ^Y or ^P or k or ^K
76              Scroll backward N lines, default 1.  The entire N lines are dis‐
77              played, even if N is more than the screen size.   Warning:  some
78              systems use ^Y as a special job control character.
79
80       u or ^U
81              Scroll  backward  N  lines, default one half of the screen size.
82              If N is specified, it becomes the new default for  subsequent  d
83              and u commands.
84
85       J      Like j, but continues to scroll beyond the end of the file.
86
87       K or Y Like  k,  but  continues  to  scroll beyond the beginning of the
88              file.
89
90       ESC-) or RIGHTARROW
91              Scroll horizontally right N characters, default half the  screen
92              width  (see  the  -#  option).   If  a number N is specified, it
93              becomes the default for future  RIGHTARROW  and  LEFTARROW  com‐
94              mands.   While  the  text  is scrolled, it acts as though the -S
95              option (chop lines) were in effect.
96
97       ESC-( or LEFTARROW
98              Scroll horizontally left N characters, default half  the  screen
99              width  (see  the  -#  option).   If  a number N is specified, it
100              becomes the default for future  RIGHTARROW  and  LEFTARROW  com‐
101              mands.
102
103       ESC-} or ^RIGHTARROW
104              Scroll  horizontally  right  to show the end of the longest dis‐
105              played line.
106
107       ESC-{ or ^LEFTARROW
108              Scroll horizontally left back to the first column.
109
110       r or ^R or ^L
111              Repaint the screen.
112
113       R      Repaint the screen, discarding any buffered  input.   Useful  if
114              the file is changing while it is being viewed.
115
116       F      Scroll  forward, and keep trying to read when the end of file is
117              reached.  Normally this command would be used  when  already  at
118              the  end of the file.  It is a way to monitor the tail of a file
119              which is growing while it is being  viewed.   (The  behavior  is
120              similar to the "tail -f" command.)
121
122       ESC-F  Like  F,  but  as soon as a line is found which matches the last
123              search pattern, the terminal bell is rung and forward  scrolling
124              stops.
125
126       g or < or ESC-<
127              Go to line N in the file, default 1 (beginning of file).  (Warn‐
128              ing: this may be slow if N is large.)
129
130       G or > or ESC->
131              Go to line N in the file, default the end of the  file.   (Warn‐
132              ing:  this  may  be slow if N is large, or if N is not specified
133              and standard input, rather than a file, is being read.)
134
135       ESC-G  Same as G, except if no number N is specified and the  input  is
136              standard  input,  goes  to  the  last  line  which  is currently
137              buffered.
138
139       p or % Go to a position N percent into the file.  N should be between 0
140              and 100, and may contain a decimal point.
141
142       P      Go to the line containing byte offset N in the file.
143
144       {      If a left curly bracket appears in the top line displayed on the
145              screen, the { command  will  go  to  the  matching  right  curly
146              bracket.   The matching right curly bracket is positioned on the
147              bottom line of the screen.  If there is more than one left curly
148              bracket  on  the top line, a number N may be used to specify the
149              N-th bracket on the line.
150
151       }      If a right curly bracket appears in the bottom line displayed on
152              the  screen,  the  }  command will go to the matching left curly
153              bracket.  The matching left curly bracket is positioned  on  the
154              top  line  of the screen.  If there is more than one right curly
155              bracket on the top line, a number N may be used to  specify  the
156              N-th bracket on the line.
157
158       (      Like {, but applies to parentheses rather than curly brackets.
159
160       )      Like }, but applies to parentheses rather than curly brackets.
161
162       [      Like  {, but applies to square brackets rather than curly brack‐
163              ets.
164
165       ]      Like }, but applies to square brackets rather than curly  brack‐
166              ets.
167
168       ESC-^F Followed  by two characters, acts like {, but uses the two char‐
169              acters as open and close brackets, respectively.   For  example,
170              "ESC  ^F < >" could be used to go forward to the > which matches
171              the < in the top displayed line.
172
173       ESC-^B Followed by two characters, acts like }, but uses the two  char‐
174              acters  as  open and close brackets, respectively.  For example,
175              "ESC ^B < >" could be used to go backward to the < which matches
176              the > in the bottom displayed line.
177
178       m      Followed  by  any lowercase or uppercase letter, marks the first
179              displayed line with  that  letter.   If  the  status  column  is
180              enabled  via  the  -J option, the status column shows the marked
181              line.
182
183       M      Acts like m, except the last displayed  line  is  marked  rather
184              than the first displayed line.
185
186       '      (Single  quote.)  Followed by any lowercase or uppercase letter,
187              returns to the position which was previously  marked  with  that
188              letter.   Followed by another single quote, returns to the posi‐
189              tion at which the last "large" movement  command  was  executed.
190              Followed  by a ^ or $, jumps to the beginning or end of the file
191              respectively.  Marks are preserved when a new file is  examined,
192              so the ' command can be used to switch between input files.
193
194       ^X^X   Same as single quote.
195
196       ESC-m  Followed  by  any lowercase or uppercase letter, clears the mark
197              identified by that letter.
198
199       /pattern
200              Search forward in the file for the N-th line containing the pat‐
201              tern.  N defaults to 1.  The pattern is a regular expression, as
202              recognized by the regular expression library  supplied  by  your
203              system.   The search starts at the first line displayed (but see
204              the -a and -j options, which change this).
205
206              Certain characters are special if entered at  the  beginning  of
207              the  pattern;  they modify the type of search rather than become
208              part of the pattern:
209
210              ^N or !
211                     Search for lines which do NOT match the pattern.
212
213              ^E or *
214                     Search multiple files.  That is, if  the  search  reaches
215                     the  END of the current file without finding a match, the
216                     search continues in the next file  in  the  command  line
217                     list.
218
219              ^F or @
220                     Begin  the  search at the first line of the FIRST file in
221                     the command line list, regardless of  what  is  currently
222                     displayed  on  the screen or the settings of the -a or -j
223                     options.
224
225              ^K     Highlight any text which matches the pattern on the  cur‐
226                     rent screen, but don't move to the first match (KEEP cur‐
227                     rent position).
228
229              ^R     Don't interpret regular expression  metacharacters;  that
230                     is, do a simple textual comparison.
231
232       ?pattern
233              Search  backward  in  the  file for the N-th line containing the
234              pattern.  The search starts at the last line displayed (but  see
235              the -a and -j options, which change this).
236
237              Certain characters are special as in the / command:
238
239              ^N or !
240                     Search for lines which do NOT match the pattern.
241
242              ^E or *
243                     Search  multiple  files.   That is, if the search reaches
244                     the beginning of  the  current  file  without  finding  a
245                     match,  the  search continues in the previous file in the
246                     command line list.
247
248              ^F or @
249                     Begin the search at the last line of the last file in the
250                     command  line  list, regardless of what is currently dis‐
251                     played on the screen or the settings  of  the  -a  or  -j
252                     options.
253
254              ^K     As in forward searches.
255
256              ^R     As in forward searches.
257
258       ESC-/pattern
259              Same as "/*".
260
261       ESC-?pattern
262              Same as "?*".
263
264       n      Repeat  previous  search, for N-th line containing the last pat‐
265              tern.  If the previous search was modified by ^N, the search  is
266              made  for the N-th line NOT containing the pattern.  If the pre‐
267              vious search was modified by ^E, the  search  continues  in  the
268              next  (or  previous)  file if not satisfied in the current file.
269              If the previous search was modified by ^R, the  search  is  done
270              without  using  regular  expressions.  There is no effect if the
271              previous search was modified by ^F or ^K.
272
273       N      Repeat previous search, but in the reverse direction.
274
275       ESC-n  Repeat previous  search,  but  crossing  file  boundaries.   The
276              effect is as if the previous search were modified by *.
277
278       ESC-N  Repeat  previous search, but in the reverse direction and cross‐
279              ing file boundaries.
280
281       ESC-u  Undo search highlighting.   Turn  off  highlighting  of  strings
282              matching the current search pattern.  If highlighting is already
283              off because of a previous ESC-u command, turn highlighting  back
284              on.   Any  search  command  will also turn highlighting back on.
285              (Highlighting can also be disabled by toggling the -G option; in
286              that case search commands do not turn highlighting back on.)
287
288       &pattern
289              Display  only  lines which match the pattern; lines which do not
290              match the pattern are not displayed.  If pattern  is  empty  (if
291              you  type  &  immediately  followed  by ENTER), any filtering is
292              turned off, and all lines are displayed.  While filtering is  in
293              effect,  an  ampersand  is  displayed  at  the  beginning of the
294              prompt, as a reminder that some lines in the file may be hidden.
295
296              Certain characters are special as in the / command:
297
298              ^N or !
299                     Display only lines which do NOT match the pattern.
300
301              ^R     Don't interpret regular expression  metacharacters;  that
302                     is, do a simple textual comparison.
303
304       :e [filename]
305              Examine  a  new file.  If the filename is missing, the "current"
306              file (see the :n and :p commands below) from the list  of  files
307              in  the  command line is re-examined.  A percent sign (%) in the
308              filename is replaced by the name of the current file.   A  pound
309              sign  (#)  is  replaced  by  the name of the previously examined
310              file.   However,  two  consecutive  percent  signs  are   simply
311              replaced with a single percent sign.  This allows you to enter a
312              filename that contains a percent sign in the  name.   Similarly,
313              two  consecutive  pound  signs  are replaced with a single pound
314              sign.  The filename is inserted into the command  line  list  of
315              files  so  that it can be seen by subsequent :n and :p commands.
316              If the filename consists of several files, they are all inserted
317              into  the  list  of files and the first one is examined.  If the
318              filename contains one or more spaces, the entire filename should
319              be enclosed in double quotes (also see the -" option).
320
321       ^X^V or E
322              Same  as :e.  Warning: some systems use ^V as a special literal‐
323              ization character.  On such systems, you may not be able to  use
324              ^V.
325
326       :n     Examine  the next file (from the list of files given in the com‐
327              mand line).  If a number N is specified, the N-th next  file  is
328              examined.
329
330       :p     Examine the previous file in the command line list.  If a number
331              N is specified, the N-th previous file is examined.
332
333       :x     Examine the first file in the command line list.  If a number  N
334              is specified, the N-th file in the list is examined.
335
336       :d     Remove the current file from the list of files.
337
338       t      Go  to the next tag, if there were more than one matches for the
339              current tag.  See the -t option for more details about tags.
340
341       T      Go to the previous tag, if there were more than one matches  for
342              the current tag.
343
344       = or ^G or :f
345              Prints  some  information about the file being viewed, including
346              its name and the line number and byte offset of the bottom  line
347              being  displayed.  If possible, it also prints the length of the
348              file, the number of lines in the file and  the  percent  of  the
349              file above the last displayed line.
350
351       -      Followed  by one of the command line option letters (see OPTIONS
352              below), this will change the setting of that option and print  a
353              message  describing  the  new  setting.   If a ^P (CONTROL-P) is
354              entered immediately after the dash, the setting of the option is
355              changed  but  no message is printed.  If the option letter has a
356              numeric value (such as -b or -h), or a string value (such as  -P
357              or  -t), a new value may be entered after the option letter.  If
358              no new value is entered, a message describing the  current  set‐
359              ting is printed and nothing is changed.
360
361       --     Like  the  -  command, but takes a long option name (see OPTIONS
362              below) rather than a single option letter.  You must press ENTER
363              or  RETURN after typing the option name.  A ^P immediately after
364              the second dash suppresses printing of a message describing  the
365              new setting, as in the - command.
366
367       -+     Followed  by  one  of  the command line option letters this will
368              reset the option to its default  setting  and  print  a  message
369              describing  the  new  setting.  (The "-+X" command does the same
370              thing as "-+X" on the command line.)  This  does  not  work  for
371              string-valued options.
372
373       --+    Like  the -+ command, but takes a long option name rather than a
374              single option letter.
375
376       -!     Followed by one of the command line option  letters,  this  will
377              reset  the  option  to the "opposite" of its default setting and
378              print a message describing the new setting.  This does not  work
379              for numeric or string-valued options.
380
381       --!    Like  the -! command, but takes a long option name rather than a
382              single option letter.
383
384       _      (Underscore.)  Followed by one of the command line  option  let‐
385              ters,  this  will print a message describing the current setting
386              of that option.  The setting of the option is not changed.
387
388       __     (Double underscore.)  Like the _ (underscore) command, but takes
389              a long option name rather than a single option letter.  You must
390              press ENTER or RETURN after typing the option name.
391
392       +cmd   Causes the specified cmd to be executed each time a new file  is
393              examined.  For example, +G causes less to initially display each
394              file starting at the end rather than the beginning.
395
396       V      Prints the version number of less being run.
397
398       q or Q or :q or :Q or ZZ
399              Exits less.
400
401       The following four commands may or may not be valid, depending on  your
402       particular installation.
403
404       v      Invokes  an  editor  to edit the current file being viewed.  The
405              editor is taken from the environment variable VISUAL if defined,
406              or  EDITOR if VISUAL is not defined, or defaults to "vi" if nei‐
407              ther VISUAL nor EDITOR is defined.  See also the  discussion  of
408              LESSEDIT under the section on PROMPTS below.
409
410       ! shell-command
411              Invokes  a shell to run the shell-command given.  A percent sign
412              (%) in the command is replaced by the name of the current  file.
413              A pound sign (#) is replaced by the name of the previously exam‐
414              ined file.  "!!" repeats the last shell command.   "!"  with  no
415              shell  command  simply  invokes  a  shell.  On Unix systems, the
416              shell is taken from the environment variable SHELL, or  defaults
417              to  "sh".   On  MS-DOS and OS/2 systems, the shell is the normal
418              command processor.
419
420       | <m> shell-command
421              <m> represents any mark letter.  Pipes a section  of  the  input
422              file  to the given shell command.  The section of the file to be
423              piped is between the position marked by the letter and the  cur‐
424              rent  screen.  The entire current screen is included, regardless
425              of whether the marked position is before or  after  the  current
426              screen.   <m> may also be ^ or $ to indicate beginning or end of
427              file respectively.  If <m> is . or newline, the  current  screen
428              is piped.
429
430       s filename
431              Save  the  input  to  a file.  This only works if the input is a
432              pipe, not an ordinary file.
433

OPTIONS

435       Command line options are described below.  Most options may be  changed
436       while less is running, via the "-" command.
437
438       Most  options  may be given in one of two forms: either a dash followed
439       by a single letter, or two dashes followed by a long  option  name.   A
440       long  option  name  may  be  abbreviated as long as the abbreviation is
441       unambiguous.  For example, --quit-at-eof may be abbreviated --quit, but
442       not --qui, since both --quit-at-eof and --quiet begin with --qui.  Some
443       long option names are in uppercase, such as --QUIT-AT-EOF, as  distinct
444       from  --quit-at-eof.  Such option names need only have their first let‐
445       ter capitalized; the remainder of the name may be in either case.   For
446       example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.
447
448       Options are also taken from the environment variable "LESS".  For exam‐
449       ple, to avoid typing "less -options ..." each time less is invoked, you
450       might tell csh:
451
452       setenv LESS "-options"
453
454       or if you use sh:
455
456       LESS="-options"; export LESS
457
458       On  MS-DOS,  you don't need the quotes, but you should replace any per‐
459       cent signs in the options string by double percent signs.
460
461       The environment variable is parsed before the command line, so  command
462       line  options  override  the  LESS  environment variable.  If an option
463       appears in the LESS variable, it can be reset to its default  value  on
464       the command line by beginning the command line option with "-+".
465
466       Some  options  like -k or -D require a string to follow the option let‐
467       ter.  The string for that option is considered to  end  when  a  dollar
468       sign  ($)  is found.  For example, you can set two -D options on MS-DOS
469       like this:
470
471       LESS="Dn9.1$Ds4.1"
472
473       If the --use-backslash option appears earlier in the  options,  then  a
474       dollar  sign or backslash may be included literally in an option string
475       by preceding it with a backslash.  If the --use-backslash option is not
476       in  effect, then backslashes are not treated specially, and there is no
477       way to include a dollar sign in the option string.
478
479       -? or --help
480              This option displays a summary of the commands accepted by  less
481              (the  same  as  the  h  command).   (Depending on how your shell
482              interprets the question mark, it may be necessary to  quote  the
483              question mark, thus: "-\?".)
484
485       -a or --search-skip-screen
486              By  default,  forward searches start at the top of the displayed
487              screen and backwards searches start at the bottom  of  the  dis‐
488              played  screen (except for repeated searches invoked by the n or
489              N commands, which  start  after  or  before  the  "target"  line
490              respectively; see the -j option for more about the target line).
491              The -a option causes forward searches to instead  start  at  the
492              bottom  of  the screen and backward searches to start at the top
493              of the screen, thus skipping all lines displayed on the screen.
494
495       -A or --SEARCH-SKIP-SCREEN
496              Causes all forward searches (not just non-repeated searches)  to
497              start  just  after the target line, and all backward searches to
498              start just before the target line.  Thus, forward searches  will
499              skip part of the displayed screen (from the first line up to and
500              including the target line).  Similarly backwards  searches  will
501              skip the displayed screen from the last line up to and including
502              the target line.  This was the default behavior in less versions
503              prior to 441.
504
505       -bn or --buffers=n
506              Specifies  the  amount  of  buffer  space less will use for each
507              file, in units of kilobytes (1024 bytes).  By  default  64 K  of
508              buffer  space  is used for each file (unless the file is a pipe;
509              see the -B option).  The -b  option  specifies  instead  that  n
510              kilobytes of buffer space should be used for each file.  If n is
511              -1, buffer space is unlimited; that is, the entire file  can  be
512              read into memory.
513
514       -B or --auto-buffers
515              By default, when data is read from a pipe, buffers are allocated
516              automatically as needed.  If a large amount of data is read from
517              the  pipe,  this  can cause a large amount of memory to be allo‐
518              cated.  The -B option disables this automatic allocation of buf‐
519              fers for pipes, so that only 64 K (or the amount of space speci‐
520              fied by the -b option) is used for the pipe.  Warning: use of -B
521              can  result  in  erroneous display, since only the most recently
522              viewed part of the piped data is kept  in  memory;  any  earlier
523              data is lost.
524
525       -c or --clear-screen
526              Causes  full  screen  repaints  to  be painted from the top line
527              down.  By default, full screen repaints are  done  by  scrolling
528              from the bottom of the screen.
529
530       -C or --CLEAR-SCREEN
531              Same as -c, for compatibility with older versions of less.
532
533       -d or --dumb
534              The -d option suppresses the error message normally displayed if
535              the terminal is dumb; that is, lacks some important  capability,
536              such as the ability to clear the screen or scroll backward.  The
537              -d option does not otherwise change the behavior of  less  on  a
538              dumb terminal.
539
540       -Dxcolor or --color=xcolor
541              [MS-DOS only] Sets the color of the text displayed.  x is a sin‐
542              gle character which selects the type  of  text  whose  color  is
543              being  set: n=normal, s=standout, d=bold, u=underlined, k=blink.
544              color is a pair of numbers separated by  a  period.   The  first
545              number  selects  the foreground color and the second selects the
546              background color of the text.  A single number N is the same  as
547              N.M,  where  M  is  the  normal background color.  The color may
548              start or end with u to use underline (with the normal color,  if
549              by  itself),  if  the  system supports it (Windows only).  x may
550              also be a to toggle strict ANSI sequence rendering (SGR mode).
551
552
553       -e or --quit-at-eof
554              Causes less to automatically exit the  second  time  it  reaches
555              end-of-file.   By  default, the only way to exit less is via the
556              "q" command.
557
558       -E or --QUIT-AT-EOF
559              Causes less to automatically exit the first time it reaches end-
560              of-file.
561
562       -f or --force
563              Forces non-regular files to be opened.  (A non-regular file is a
564              directory or a device special file.)  Also suppresses the  warn‐
565              ing message when a binary file is opened.  By default, less will
566              refuse to open non-regular files.  Note that some operating sys‐
567              tems will not allow directories to be read, even if -f is set.
568
569       -F or --quit-if-one-screen
570              Causes less to automatically exit if the entire file can be dis‐
571              played on the first screen.
572
573       -g or --hilite-search
574              Normally, less will highlight ALL strings which match  the  last
575              search  command.   The  -g option changes this behavior to high‐
576              light only the particular string which was  found  by  the  last
577              search command.  This can cause less to run somewhat faster than
578              the default.
579
580       -G or --HILITE-SEARCH
581              The -G option suppresses all highlighting of  strings  found  by
582              search commands.
583
584       --old-bot
585              Reverts to the old bottom of screen behavior.  This can be some‐
586              times desirable  if  the  long lines are not wrapped   correctly
587              when  reaching  the  bottom  of  the  terminal,  while scrolling
588              forward.
589
590       -hn or --max-back-scroll=n
591              Specifies a maximum number of lines to scroll backward.   If  it
592              is necessary to scroll backward more than n lines, the screen is
593              repainted in a forward direction instead.  (If the terminal does
594              not have the ability to scroll backward, -h0 is implied.)
595
596       -i or --ignore-case
597              Causes searches to ignore case; that is, uppercase and lowercase
598              are considered identical.  This option is ignored if any  upper‐
599              case  letters appear in the search pattern; in other words, if a
600              pattern contains uppercase letters, then that  search  does  not
601              ignore case.
602
603       -I or --IGNORE-CASE
604              Like  -i,  but searches ignore case even if the pattern contains
605              uppercase letters.
606
607       -jn or --jump-target=n
608              Specifies a line on the screen where the "target" line is to  be
609              positioned.   The  target line is the line specified by any com‐
610              mand to search for a pattern, jump to a line number, jump  to  a
611              file percentage or jump to a tag.  The screen line may be speci‐
612              fied by a number: the top line on the screen is 1, the  next  is
613              2, and so on.  The number may be negative to specify a line rel‐
614              ative to the bottom of the screen: the bottom line on the screen
615              is  -1, the second to the bottom is -2, and so on.  Alternately,
616              the screen line may be specified as a fraction of the height  of
617              the  screen,  starting with a decimal point: .5 is in the middle
618              of the screen, .3 is three tenths down from the first line,  and
619              so  on.  If the line is specified as a fraction, the actual line
620              number is recalculated if the terminal  window  is  resized,  so
621              that  the  target  line remains at the specified fraction of the
622              screen height.  If any form of the -j option is  used,  repeated
623              forward  searches  (invoked  with  "n" or "N") begin at the line
624              immediately  after  the  target  line,  and  repeated   backward
625              searches  begin  at the target line, unless changed by -a or -A.
626              For example, if "-j4" is used, the target  line  is  the  fourth
627              line  on the screen, so forward searches begin at the fifth line
628              on the screen.  However nonrepeated searches (invoked  with  "/"
629              or  "?")  always begin at the start or end of the current screen
630              respectively.
631
632       -J or --status-column
633              Displays a status column at the left edge of  the  screen.   The
634              status  column  shows the lines that matched the current search,
635              and any lines that are marked (via the m  or  M  command).   The
636              status column is also used if the -w or -W option is in effect.
637
638       -kfilename or --lesskey-file=filename
639              Causes  less  to  open and interpret the named file as a lesskey
640              (1) file.  Multiple -k options may be specified.  If the LESSKEY
641              or  LESSKEY_SYSTEM  environment variable is set, or if a lesskey
642              file is found in a standard place (see KEY BINDINGS), it is also
643              used as a lesskey file.
644
645       -K or --quit-on-intr
646              Causes  less  to exit immediately (with status 2) when an inter‐
647              rupt character (usually ^C) is typed.   Normally,  an  interrupt
648              character causes less to stop whatever it is doing and return to
649              its command prompt.  Note that  use  of  this  option  makes  it
650              impossible to return to the command prompt from the "F" command.
651
652       -L or --no-lessopen
653              Ignore  the  LESSOPEN  environment  variable (see the INPUT PRE‐
654              PROCESSOR section below).  This option can be  set  from  within
655              less,  but  it will apply only to files opened subsequently, not
656              to the file which is currently open.
657
658       -m or --long-prompt
659              Causes less to prompt verbosely (like more),  with  the  percent
660              into the file.  By default, less prompts with a colon.
661
662       -M or --LONG-PROMPT
663              Causes less to prompt even more verbosely than more.
664
665       -n or --line-numbers
666              Suppresses  line numbers.  The default (to use line numbers) may
667              cause less to run more slowly in some cases, especially  with  a
668              very  large  input  file.   Suppressing line numbers with the -n
669              option will avoid this problem.  Using line numbers  means:  the
670              line number will be displayed in the verbose prompt and in the =
671              command, and the v command will pass the current line number  to
672              the  editor  (see  also  the  discussion  of LESSEDIT in PROMPTS
673              below).
674
675       -N or --LINE-NUMBERS
676              Causes a line number to be displayed at the  beginning  of  each
677              line in the display.
678
679       -ofilename or --log-file=filename
680              Causes  less  to copy its input to the named file as it is being
681              viewed.  This applies only when the input file is a pipe, not an
682              ordinary  file.   If  the file already exists, less will ask for
683              confirmation before overwriting it.
684
685       -Ofilename or --LOG-FILE=filename
686              The -O option is like -o, but it will overwrite an existing file
687              without asking for confirmation.
688
689              If  no log file has been specified, the -o and -O options can be
690              used from within less to specify a log  file.   Without  a  file
691              name, they will simply report the name of the log file.  The "s"
692              command is equivalent to specifying -o from within less.
693
694       -ppattern or --pattern=pattern
695              The -p option on the command line is  equivalent  to  specifying
696              +/pattern;  that  is, it tells less to start at the first occur‐
697              rence of pattern in the file.
698
699       -Pprompt or --prompt=prompt
700              Provides a way to tailor the three prompt  styles  to  your  own
701              preference.  This option would normally be put in the LESS envi‐
702              ronment variable, rather than being typed in with each less com‐
703              mand.  Such an option must either be the last option in the LESS
704              variable, or be terminated by a dollar sign.
705               -Ps followed by a string changes the default (short) prompt  to
706              that string.
707               -Pm changes the medium (-m) prompt.
708               -PM changes the long (-M) prompt.
709               -Ph changes the prompt for the help screen.
710               -P= changes the message printed by the = command.
711               -Pw  changes the message printed while waiting for data (in the
712              F command).
713
714              All prompt strings consist of a sequence of letters and  special
715              escape sequences.  See the section on PROMPTS for more details.
716
717       -q or --quiet or --silent
718              Causes  moderately  "quiet"  operation: the terminal bell is not
719              rung if an attempt is made to scroll past the end of the file or
720              before the beginning of the file.  If the terminal has a "visual
721              bell", it is used instead.  The bell will  be  rung  on  certain
722              other  errors, such as typing an invalid character.  The default
723              is to ring the terminal bell in all such cases.
724
725       -Q or --QUIET or --SILENT
726              Causes totally "quiet" operation: the  terminal  bell  is  never
727              rung.
728
729       -r or --raw-control-chars
730              Causes "raw" control characters to be displayed.  The default is
731              to display control characters  using  the  caret  notation;  for
732              example, a control-A (octal 001) is displayed as "^A".  Warning:
733              when the -r option is used, less cannot keep track of the actual
734              appearance  of  the screen (since this depends on how the screen
735              responds to each type of control character).  Thus, various dis‐
736              play  problems may result, such as long lines being split in the
737              wrong place.
738
739       -R or --RAW-CONTROL-CHARS
740              Like -r, but only ANSI "color" escape sequences  are  output  in
741              "raw" form.  Unlike -r, the screen appearance is maintained cor‐
742              rectly  in  most  cases.   ANSI  "color"  escape  sequences  are
743              sequences of the form:
744
745                   ESC [ ... m
746
747              where  the  "..." is zero or more color specification characters
748              For the purpose of keeping  track  of  screen  appearance,  ANSI
749              color  escape sequences are assumed to not move the cursor.  You
750              can make less think that characters other than "m" can end  ANSI
751              color  escape  sequences  by  setting  the  environment variable
752              LESSANSIENDCHARS to the list of characters which can end a color
753              escape  sequence.   And  you can make less think that characters
754              other than the standard ones may appear between the ESC and  the
755              m  by  setting  the environment variable LESSANSIMIDCHARS to the
756              list of characters which can appear.
757
758       -s or --squeeze-blank-lines
759              Causes consecutive blank lines to  be  squeezed  into  a  single
760              blank line.  This is useful when viewing nroff output.
761
762       -S or --chop-long-lines
763              Causes  lines  longer than the screen width to be chopped (trun‐
764              cated) rather than wrapped.  That is, the portion of a long line
765              that does not fit in the screen width is not shown.  The default
766              is to wrap long lines; that is, display  the  remainder  on  the
767              next line.
768
769       -ttag or --tag=tag
770              The -t option, followed immediately by a TAG, will edit the file
771              containing that tag.  For this to work, tag information must  be
772              available;  for  example,  there  may  be  a file in the current
773              directory called "tags", which was previously built by ctags (1)
774              or an equivalent command.  If the environment variable LESSGLOB‐
775              ALTAGS is set, it is taken to be the name of a command  compati‐
776              ble  with  global  (1), and that command is executed to find the
777              tag.  (See http://www.gnu.org/software/global/global.html).  The
778              -t  option  may  also be specified from within less (using the -
779              command) as a way of examining a new file.  The command ":t"  is
780              equivalent to specifying -t from within less.
781
782       -Ttagsfile or --tag-file=tagsfile
783              Specifies a tags file to be used instead of "tags".
784
785       -u or --underline-special
786              Causes  backspaces  and carriage returns to be treated as print‐
787              able characters; that is, they are sent  to  the  terminal  when
788              they appear in the input.
789
790       -U or --UNDERLINE-SPECIAL
791              Causes  backspaces, tabs, carriage returns and "formatting char‐
792              acters" (as defined by Unicode) to be treated as control charac‐
793              ters; that is, they are handled as specified by the -r option.
794
795              By  default,  if  neither  -u  nor -U is given, backspaces which
796              appear adjacent to an  underscore  character  are  treated  spe‐
797              cially:  the  underlined  text is displayed using the terminal's
798              hardware underlining capability.  Also, backspaces which  appear
799              between  two  identical  characters  are  treated specially: the
800              overstruck text is printed using the terminal's  hardware  bold‐
801              face  capability.   Other backspaces are deleted, along with the
802              preceding character.  Carriage returns immediately followed by a
803              newline  are  deleted.   Other  carriage  returns are handled as
804              specified by the -r option.  Text which is overstruck or  under‐
805              lined can be searched for if neither -u nor -U is in effect.
806
807       -V or --version
808              Displays the version number of less.
809
810       -w or --hilite-unread
811              Temporarily  highlights  the  first  "new"  line after a forward
812              movement of a full page.  The first "new" line is the line imme‐
813              diately  following  the  line  previously  at  the bottom of the
814              screen.  Also highlights the target line after a g or p command.
815              The  highlight is removed at the next command which causes move‐
816              ment.  The entire line is highlighted, unless the -J  option  is
817              in effect, in which case only the status column is highlighted.
818
819       -W or --HILITE-UNREAD
820              Like -w, but temporarily highlights the first new line after any
821              forward movement command larger than one line.
822
823       -xn,... or --tabs=n,...
824              Sets tab stops.  If only one n is specified, tab stops  are  set
825              at  multiples  of n.  If multiple values separated by commas are
826              specified, tab stops are set at those positions, and  then  con‐
827              tinue  with  the  same  spacing  as  the last two.  For example,
828              -x9,17 will set tabs at positions  9,  17,  25,  33,  etc.   The
829              default for n is 8.
830
831       -X or --no-init
832              Disables sending the termcap initialization and deinitialization
833              strings to the terminal.  This is  sometimes  desirable  if  the
834              deinitialization  string does something unnecessary, like clear‐
835              ing the screen.
836
837       -yn or --max-forw-scroll=n
838              Specifies a maximum number of lines to scroll forward.  If it is
839              necessary  to  scroll  forward  more than n lines, the screen is
840              repainted instead.  The -c or -C option may be used  to  repaint
841              from  the top of the screen if desired.  By default, any forward
842              movement causes scrolling.
843
844       -zn or --window=n or -n
845              Changes the default scrolling  window  size  to  n  lines.   The
846              default is one screenful.  The z and w commands can also be used
847              to change the window size.  The "z" may be omitted for  compati‐
848              bility with some versions of more.  If the number n is negative,
849              it indicates n lines less than the  current  screen  size.   For
850              example, if the screen is 24 lines, -z-4 sets the scrolling win‐
851              dow to 20 lines.  If the screen is  resized  to  40  lines,  the
852              scrolling window automatically changes to 36 lines.
853
854       -"cc or --quotes=cc
855              Changes  the  filename quoting character.  This may be necessary
856              if you are trying to name a file which contains both spaces  and
857              quote  characters.  Followed by a single character, this changes
858              the quote character to that character.  Filenames  containing  a
859              space should then be surrounded by that character rather than by
860              double quotes.  Followed by two  characters,  changes  the  open
861              quote  to the first character, and the close quote to the second
862              character.  Filenames containing a space should then be preceded
863              by  the  open  quote  character  and followed by the close quote
864              character.  Note  that  even  after  the  quote  characters  are
865              changed,  this  option  remains  -" (a dash followed by a double
866              quote).
867
868       -~ or --tilde
869              Normally lines after end of file are displayed as a single tilde
870              (~).  This option causes lines after end of file to be displayed
871              as blank lines.
872
873       -# or --shift
874              Specifies the default number of positions to scroll horizontally
875              in  the RIGHTARROW and LEFTARROW commands.  If the number speci‐
876              fied is zero, it sets the default number  of  positions  to  one
877              half of the screen width.  Alternately, the number may be speci‐
878              fied as a fraction of the width of the screen, starting  with  a
879              decimal  point:  .5  is  half  of  the screen width, .3 is three
880              tenths of the screen width, and so on.  If the number is  speci‐
881              fied  as  a  fraction,  the actual number of scroll positions is
882              recalculated if the terminal window  is  resized,  so  that  the
883              actual  scroll  remains  at the specified fraction of the screen
884              width.
885
886       --follow-name
887              Normally, if the input file is renamed while  an  F  command  is
888              executing,  less  will  continue  to display the contents of the
889              original file despite its  name  change.   If  --follow-name  is
890              specified, during an F command less will periodically attempt to
891              reopen the file by name.  If the reopen succeeds and the file is
892              a  different file from the original (which means that a new file
893              has been created  with  the  same  name  as  the  original  (now
894              renamed) file), less will display the contents of that new file.
895
896       --no-keypad
897              Disables  sending the keypad initialization and deinitialization
898              strings to the terminal.  This is sometimes useful if the keypad
899              strings make the numeric keypad behave in an undesirable manner.
900
901       --use-backslash
902              This  option changes the interpretations of options which follow
903              this one.  After the --use-backslash option, any backslash in an
904              option  string  is  removed and the following character is taken
905              literally.  This allows a dollar sign to be included  in  option
906              strings.
907
908       --rscroll
909              This  option changes the character used to mark truncated lines.
910              It may begin with a two-character attribute indicator like LESS‐
911              BINFMT  does.   If  there is no attribute indicator, standout is
912              used.  If set to "-", truncated lines are not marked.
913
914       --     A command line argument of "--" marks the end  of  option  argu‐
915              ments.   Any  arguments  following this are interpreted as file‐
916              names.  This can be useful when viewing a file whose name begins
917              with a "-" or "+".
918
919       +      If  a  command  line option begins with +, the remainder of that
920              option is taken to be an initial command to less.  For  example,
921              +G  tells  less  to start at the end of the file rather than the
922              beginning, and +/xyz tells it to start at the  first  occurrence
923              of  "xyz"  in  the file.  As a special case, +<number> acts like
924              +<number>g; that is, it starts the display at the specified line
925              number  (however,  see  the caveat under the "g" command above).
926              If the option starts with ++, the  initial  command  applies  to
927              every  file being viewed, not just the first one.  The + command
928              described previously may also be used to set (or change) an ini‐
929              tial command for every file.
930
931

LINE EDITING

933       When  entering command line at the bottom of the screen (for example, a
934       filename for the :e command, or the pattern for a search command), cer‐
935       tain  keys  can  be used to manipulate the command line.  Most commands
936       have an alternate form in [ brackets ] which can be used if a key  does
937       not  exist  on  a  particular keyboard.  (Note that the forms beginning
938       with ESC do not work in some MS-DOS and Windows systems because ESC  is
939       the  line  erase  character.)  Any of these special keys may be entered
940       literally by preceding it with the "literal" character,  either  ^V  or
941       ^A.   A  backslash itself may also be entered literally by entering two
942       backslashes.
943
944       LEFTARROW [ ESC-h ]
945              Move the cursor one space to the left.
946
947       RIGHTARROW [ ESC-l ]
948              Move the cursor one space to the right.
949
950       ^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
951              (That is, CONTROL and LEFTARROW simultaneously.)  Move the  cur‐
952              sor one word to the left.
953
954       ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
955              (That is, CONTROL and RIGHTARROW simultaneously.)  Move the cur‐
956              sor one word to the right.
957
958       HOME [ ESC-0 ]
959              Move the cursor to the beginning of the line.
960
961       END [ ESC-$ ]
962              Move the cursor to the end of the line.
963
964       BACKSPACE
965              Delete the character to the left of the cursor,  or  cancel  the
966              command if the command line is empty.
967
968       DELETE or [ ESC-x ]
969              Delete the character under the cursor.
970
971       ^BACKSPACE [ ESC-BACKSPACE ]
972              (That  is,  CONTROL  and  BACKSPACE simultaneously.)  Delete the
973              word to the left of the cursor.
974
975       ^DELETE [ ESC-X or ESC-DELETE ]
976              (That is, CONTROL and DELETE simultaneously.)  Delete  the  word
977              under the cursor.
978
979       UPARROW [ ESC-k ]
980              Retrieve  the  previous  command  line.  If you first enter some
981              text and then press UPARROW, it will retrieve the previous  com‐
982              mand which begins with that text.
983
984       DOWNARROW [ ESC-j ]
985              Retrieve  the  next  command line.  If you first enter some text
986              and then press DOWNARROW, it  will  retrieve  the  next  command
987              which begins with that text.
988
989       TAB    Complete  the partial filename to the left of the cursor.  If it
990              matches more than one filename, the first match is entered  into
991              the  command  line.   Repeated  TABs  will  cycle thru the other
992              matching filenames.  If the completed filename is a directory, a
993              "/"  is  appended to the filename.  (On MS-DOS systems, a "\" is
994              appended.)  The environment variable LESSSEPARATOR can  be  used
995              to specify a different character to append to a directory name.
996
997       BACKTAB [ ESC-TAB ]
998              Like, TAB, but cycles in the reverse direction thru the matching
999              filenames.
1000
1001       ^L     Complete the partial filename to the left of the cursor.  If  it
1002              matches more than one filename, all matches are entered into the
1003              command line (if they fit).
1004
1005       ^U (Unix and OS/2) or ESC (MS-DOS)
1006              Delete the entire command line, or cancel  the  command  if  the
1007              command line is empty.  If you have changed your line-kill char‐
1008              acter in Unix to something other than ^U, that character is used
1009              instead of ^U.
1010
1011       ^G     Delete the entire command line and return to the main prompt.
1012
1013

KEY BINDINGS

1015       You  may define your own less commands by using the program lesskey (1)
1016       to create a lesskey file.  This file specifies a set  of  command  keys
1017       and  an  action  associated with each key.  You may also use lesskey to
1018       change the line-editing keys (see LINE EDITING), and to set environment
1019       variables.   If the environment variable LESSKEY is set, less uses that
1020       as the name of the lesskey file.  Otherwise, less looks in  a  standard
1021       place  for  the lesskey file: On Unix systems, less looks for a lesskey
1022       file called "$HOME/.less".  On MS-DOS and Windows systems,  less  looks
1023       for  a lesskey file called "$HOME/_less", and if it is not found there,
1024       then looks for a lesskey file called "_less" in any directory specified
1025       in  the  PATH  environment variable.  On OS/2 systems, less looks for a
1026       lesskey file called "$HOME/less.ini", and if  it  is  not  found,  then
1027       looks  for  a lesskey file called "less.ini" in any directory specified
1028       in the INIT environment variable, and if it not found there, then looks
1029       for  a lesskey file called "less.ini" in any directory specified in the
1030       PATH environment variable.   See  the  lesskey  manual  page  for  more
1031       details.
1032
1033       A  system-wide lesskey file may also be set up to provide key bindings.
1034       If a key is defined in both a local lesskey file and in the system-wide
1035       file,  key bindings in the local file take precedence over those in the
1036       system-wide file.  If the environment variable LESSKEY_SYSTEM  is  set,
1037       less uses that as the name of the system-wide lesskey file.  Otherwise,
1038       less looks in a standard place for the  system-wide  lesskey  file:  On
1039       Unix  systems,  the system-wide lesskey file is /usr/local/etc/sysless.
1040       (However, if less was built with a  different  sysconf  directory  than
1041       /usr/local/etc, that directory is where the sysless file is found.)  On
1042       MS-DOS and Windows systems, the system-wide lesskey  file  is  c:\_sys‐
1043       less.  On OS/2 systems, the system-wide lesskey file is c:\sysless.ini.
1044
1045

INPUT PREPROCESSOR

1047       You  may  define an "input preprocessor" for less.  Before less opens a
1048       file, it first gives your input preprocessor a chance to modify the way
1049       the  contents of the file are displayed.  An input preprocessor is sim‐
1050       ply an executable program (or shell script), which writes the  contents
1051       of the file to a different file, called the replacement file.  The con‐
1052       tents of the replacement file are then displayed in place of  the  con‐
1053       tents  of the original file.  However, it will appear to the user as if
1054       the original file is opened; that is, less will  display  the  original
1055       filename as the name of the current file.
1056
1057       An  input preprocessor receives one command line argument, the original
1058       filename, as entered by the user.  It  should  create  the  replacement
1059       file,  and when finished, print the name of the replacement file to its
1060       standard output.  If the input preprocessor does not output a  replace‐
1061       ment  filename, less uses the original file, as normal.  The input pre‐
1062       processor is not called when viewing standard  input.   To  set  up  an
1063       input  preprocessor, set the LESSOPEN environment variable to a command
1064       line which will invoke your  input  preprocessor.   This  command  line
1065       should  include  one  occurrence  of  the  string  "%s",  which will be
1066       replaced by  the  filename  when  the  input  preprocessor  command  is
1067       invoked.
1068
1069       When less closes a file opened in such a way, it will call another pro‐
1070       gram, called the input postprocessor, which  may  perform  any  desired
1071       clean-up  action  (such  as  deleting  the  replacement file created by
1072       LESSOPEN).  This program receives two command line arguments, the orig‐
1073       inal  filename  as entered by the user, and the name of the replacement
1074       file.  To set up an input postprocessor, set the LESSCLOSE  environment
1075       variable  to a command line which will invoke your input postprocessor.
1076       It may include two  occurrences  of  the  string  "%s";  the  first  is
1077       replaced  with  the  original  name of the file and the second with the
1078       name of the replacement file, which was output by LESSOPEN.
1079
1080       For example, on many Unix systems, these two scripts will allow you  to
1081       keep files in compressed format, but still let less view them directly:
1082
1083       lessopen.sh:
1084            #! /bin/sh
1085            case "$1" in
1086            *.Z) uncompress -c $1  >/tmp/less.$$  2>/dev/null
1087                 if [ -s /tmp/less.$$ ]; then
1088                      echo /tmp/less.$$
1089                 else
1090                      rm -f /tmp/less.$$
1091                 fi
1092                 ;;
1093            esac
1094
1095       lessclose.sh:
1096            #! /bin/sh
1097            rm $2
1098
1099       To  use these scripts, put them both where they can be executed and set
1100       LESSOPEN="lessopen.sh %s",  and  LESSCLOSE="lessclose.sh %s %s".   More
1101       complex  LESSOPEN  and LESSCLOSE scripts may be written to accept other
1102       types of compressed files, and so on.
1103
1104       It is also possible to set up an input preprocessor to  pipe  the  file
1105       data  directly to less, rather than putting the data into a replacement
1106       file.  This avoids the need to decompress the entire file before start‐
1107       ing to view it.  An input preprocessor that works this way is called an
1108       input pipe.  An input pipe, instead of writing the name of  a  replace‐
1109       ment  file  on  its  standard output, writes the entire contents of the
1110       replacement file on its standard output.  If the input  pipe  does  not
1111       write  any characters on its standard output, then there is no replace‐
1112       ment file and less uses the original file, as normal.  To use an  input
1113       pipe,  make  the first character in the LESSOPEN environment variable a
1114       vertical bar (|) to signify that the input  preprocessor  is  an  input
1115       pipe.   As  with  non-pipe input preprocessors, the command string must
1116       contain one occurrence of %s, which is replaced with  the  filename  of
1117       the input file.
1118
1119       For  example, on many Unix systems, this script will work like the pre‐
1120       vious example scripts:
1121
1122       lesspipe.sh:
1123            #! /bin/sh
1124            case "$1" in
1125            *.Z) uncompress -c $1  2>/dev/null
1126            *)   exit 1
1127                 ;;
1128            esac
1129            exit $?
1130
1131       To  use  this  script,  put  it  where  it  can  be  executed  and  set
1132       LESSOPEN="|lesspipe.sh %s".
1133
1134       Note  that  a  preprocessor  cannot output an empty file, since that is
1135       interpreted as meaning there is no replacement, and the  original  file
1136       is used.  To avoid this, if LESSOPEN starts with two vertical bars, the
1137       exit status of the script becomes meaningful.  If the  exit  status  is
1138       zero,  the  output  is considered to be replacement text, even if it is
1139       empty.  If the exit status is nonzero, any output is  ignored  and  the
1140       original  file  is  used.   For compatibility with previous versions of
1141       less, if LESSOPEN starts with only one vertical bar, the exit status of
1142       the preprocessor is ignored.
1143
1144       When  an input pipe is used, a LESSCLOSE postprocessor can be used, but
1145       it is usually not necessary since there is no replacement file to clean
1146       up.   In  this  case, the replacement file name passed to the LESSCLOSE
1147       postprocessor is "-".
1148
1149       For compatibility with previous versions of less, the input  preproces‐
1150       sor or pipe is not used if less is viewing standard input.  However, if
1151       the first character of LESSOPEN is a dash (-), the  input  preprocessor
1152       is  used  on  standard input as well as other files.  In this case, the
1153       dash is not considered to be part  of  the  preprocessor  command.   If
1154       standard input is being viewed, the input preprocessor is passed a file
1155       name consisting of a single dash.  Similarly, if the first two  charac‐
1156       ters  of  LESSOPEN  are vertical bar and dash (|-) or two vertical bars
1157       and a dash (||-), the input pipe is used on standard input as  well  as
1158       other files.  Again, in this case the dash is not considered to be part
1159       of the input pipe command.
1160
1161       There are used following files to set up default preprocessor:
1162            /etc/profile.d/less.sh
1163            /etc/profile.d/less.csh
1164       These files set up /usr/bin/lesspipe.sh as a default  filter.  An  user
1165       defined filter can be specified in ~/.lessfilter. This file should have
1166       an execute bit set and accept only one parameter,  which  represents  a
1167       filename.  If  the user defined filter process the file, zero should be
1168       returned. Otherwise ~/.lessfilter tries to handle the file.
1169
1170

NATIONAL CHARACTER SETS

1172       There are three types of characters in the input file:
1173
1174       normal characters
1175              can be displayed directly to the screen.
1176
1177       control characters
1178              should not be displayed directly, but are expected to  be  found
1179              in ordinary text files (such as backspace and tab).
1180
1181       binary characters
1182              should  not  be  displayed  directly  and are not expected to be
1183              found in text files.
1184
1185       A "character set" is simply a description of which characters are to be
1186       considered  normal,  control,  and binary.  The LESSCHARSET environment
1187       variable may be used to select a character set.   Possible  values  for
1188       LESSCHARSET are:
1189
1190       ascii  BS,  TAB, NL, CR, and formfeed are control characters, all chars
1191              with values between 32 and 126 are normal, and  all  others  are
1192              binary.
1193
1194       iso8859
1195              Selects  an  ISO 8859 character set.  This is the same as ASCII,
1196              except characters between 160 and  255  are  treated  as  normal
1197              characters.
1198
1199       latin1 Same as iso8859.
1200
1201       latin9 Same as iso8859.
1202
1203       dos    Selects a character set appropriate for MS-DOS.
1204
1205       ebcdic Selects an EBCDIC character set.
1206
1207       IBM-1047
1208              Selects  an  EBCDIC  character set used by OS/390 Unix Services.
1209              This is the EBCDIC analogue of latin1.  You get similar  results
1210              by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
1211              environment.
1212
1213       koi8-r Selects a Russian character set.
1214
1215       next   Selects a character set appropriate for NeXT computers.
1216
1217       utf-8  Selects the UTF-8 encoding  of  the  ISO  10646  character  set.
1218              UTF-8  is  special  in that it supports multi-byte characters in
1219              the input file.  It is the  only  character  set  that  supports
1220              multi-byte characters.
1221
1222       windows
1223              Selects  a  character  set appropriate for Microsoft Windows (cp
1224              1251).
1225
1226       In rare cases, it may be desired to tailor less to use a character  set
1227       other  than the ones definable by LESSCHARSET.  In this case, the envi‐
1228       ronment variable LESSCHARDEF can be used to define a character set.  It
1229       should be set to a string where each character in the string represents
1230       one character in the character set.  The character "." is  used  for  a
1231       normal  character, "c" for control, and "b" for binary.  A decimal num‐
1232       ber may be used for repetition.   For  example,  "bccc4b."  would  mean
1233       character  0  is  binary,  1,  2  and  3 are control, 4, 5, 6 and 7 are
1234       binary, and 8 is normal.  All characters after the last are taken to be
1235       the  same  as  the  last,  so characters 9 through 255 would be normal.
1236       (This is an example, and does not necessarily represent any real  char‐
1237       acter set.)
1238
1239       This  table  shows the value of LESSCHARDEF which is equivalent to each
1240       of the possible values for LESSCHARSET:
1241
1242            ascii     8bcccbcc18b95.b
1243            dos       8bcccbcc12bc5b95.b.
1244            ebcdic    5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
1245                      9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
1246            IBM-1047  4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
1247                      191.b
1248            iso8859   8bcccbcc18b95.33b.
1249            koi8-r    8bcccbcc18b95.b128.
1250            latin1    8bcccbcc18b95.33b.
1251            next      8bcccbcc18b95.bb125.bb
1252
1253       If neither LESSCHARSET nor LESSCHARDEF is set, but any of  the  strings
1254       "UTF-8",  "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_CTYPE or
1255       LANG environment variables, then the default character set is utf-8.
1256
1257       If that string is not found, but your  system  supports  the  setlocale
1258       interface,  less  will  use  setlocale  to determine the character set.
1259       setlocale is controlled by setting the  LANG  or  LC_CTYPE  environment
1260       variables.
1261
1262       Finally,  if the setlocale interface is also not available, the default
1263       character set is latin1.
1264
1265       Control and  binary  characters  are  displayed  in  standout  (reverse
1266       video).  Each such character is displayed in caret notation if possible
1267       (e.g. ^A for control-A).  Caret notation is used only if inverting  the
1268       0100 bit results in a normal printable character.  Otherwise, the char‐
1269       acter is displayed as a hex number in angle brackets.  This format  can
1270       be  changed by setting the LESSBINFMT environment variable.  LESSBINFMT
1271       may begin with a "*" and one character to select the display attribute:
1272       "*k"  is  blinking, "*d" is bold, "*u" is underlined, "*s" is standout,
1273       and "*n" is normal.  If LESSBINFMT does not begin with  a  "*",  normal
1274       attribute  is  assumed.   The remainder of LESSBINFMT is a string which
1275       may include one printf-style escape sequence (a % followed by x, X,  o,
1276       d,  etc.).   For  example, if LESSBINFMT is "*u[%x]", binary characters
1277       are displayed in underlined hexadecimal surrounded  by  brackets.   The
1278       default  if  no  LESSBINFMT  is  specified is "*s<%02X>".  Warning: the
1279       result of expanding the character via LESSBINFMT must be less  than  31
1280       characters.
1281
1282       When the character set is utf-8, the LESSUTFBINFMT environment variable
1283       acts similarly to LESSBINFMT but it applies to Unicode code points that
1284       were  successfully  decoded but are unsuitable for display (e.g., unas‐
1285       signed code points).  Its default  value  is  "<U+%04lX>".   Note  that
1286       LESSUTFBINFMT  and  LESSBINFMT  share  their  display attribute setting
1287       ("*x") so specifying one will affect both; LESSUTFBINFMT is read  after
1288       LESSBINFMT  so  its  setting,  if any, will have priority.  Problematic
1289       octets in a UTF-8 file (octets of a truncated  sequence,  octets  of  a
1290       complete  but  non-shortest  form  sequence,  illegal octets, and stray
1291       trailing octets) are displayed individually using LESSBINFMT so  as  to
1292       facilitate diagnostic of how the UTF-8 file is ill-formed.
1293
1294

PROMPTS

1296       The  -P option allows you to tailor the prompt to your preference.  The
1297       string given to the -P option replaces  the  specified  prompt  string.
1298       Certain characters in the string are interpreted specially.  The prompt
1299       mechanism is rather complicated to provide flexibility, but  the  ordi‐
1300       nary  user need not understand the details of constructing personalized
1301       prompt strings.
1302
1303       A percent sign followed by a single character is expanded according  to
1304       what the following character is:
1305
1306       %bX    Replaced  by the byte offset into the current input file.  The b
1307              is followed by a single character (shown as X above) which spec‐
1308              ifies  the line whose byte offset is to be used.  If the charac‐
1309              ter is a "t", the byte offset of the top line in the display  is
1310              used, an "m" means use the middle line, a "b" means use the bot‐
1311              tom line, a "B" means use the line just after the  bottom  line,
1312              and  a  "j"  means use the "target" line, as specified by the -j
1313              option.
1314
1315       %B     Replaced by the size of the current input file.
1316
1317       %c     Replaced by the column number of the text appearing in the first
1318              column of the screen.
1319
1320       %dX    Replaced  by  the  page number of a line in the input file.  The
1321              line to be used is determined by the X, as with the %b option.
1322
1323       %D     Replaced by the number of pages in the input  file,  or  equiva‐
1324              lently, the page number of the last line in the input file.
1325
1326       %E     Replaced  by the name of the editor (from the VISUAL environment
1327              variable, or the EDITOR environment variable if  VISUAL  is  not
1328              defined).  See the discussion of the LESSEDIT feature below.
1329
1330       %f     Replaced by the name of the current input file.
1331
1332       %F     Replaced  by the last component of the name of the current input
1333              file.
1334
1335       %i     Replaced by the index of the current file in the list  of  input
1336              files.
1337
1338       %lX    Replaced  by  the  line number of a line in the input file.  The
1339              line to be used is determined by the X, as with the %b option.
1340
1341       %L     Replaced by the line number of the last line in the input file.
1342
1343       %m     Replaced by the total number of input files.
1344
1345       %pX    Replaced by the percent into the current input  file,  based  on
1346              byte  offsets.  The line used is determined by the X as with the
1347              %b option.
1348
1349       %PX    Replaced by the percent into the current input  file,  based  on
1350              line  numbers.  The line used is determined by the X as with the
1351              %b option.
1352
1353       %s     Same as %B.
1354
1355       %t     Causes any trailing spaces to be removed.  Usually used  at  the
1356              end of the string, but may appear anywhere.
1357
1358       %T     Normally  expands  to the word "file".  However if viewing files
1359              via a tags list using the -t option,  it  expands  to  the  word
1360              "tag".
1361
1362       %x     Replaced by the name of the next input file in the list.
1363
1364       If any item is unknown (for example, the file size if input is a pipe),
1365       a question mark is printed instead.
1366
1367       The format of the prompt string can be  changed  depending  on  certain
1368       conditions.   A  question mark followed by a single character acts like
1369       an "IF": depending on the following character, a  condition  is  evalu‐
1370       ated.   If the condition is true, any characters following the question
1371       mark and condition character, up to  a  period,  are  included  in  the
1372       prompt.   If  the condition is false, such characters are not included.
1373       A colon appearing between the question mark and the period can be  used
1374       to establish an "ELSE": any characters between the colon and the period
1375       are included in the string if and only if the IF  condition  is  false.
1376       Condition characters (which follow a question mark) may be:
1377
1378       ?a     True if any characters have been included in the prompt so far.
1379
1380       ?bX    True if the byte offset of the specified line is known.
1381
1382       ?B     True if the size of current input file is known.
1383
1384       ?c     True if the text is horizontally shifted (%c is not zero).
1385
1386       ?dX    True if the page number of the specified line is known.
1387
1388       ?e     True if at end-of-file.
1389
1390       ?f     True  if  there is an input filename (that is, if input is not a
1391              pipe).
1392
1393       ?lX    True if the line number of the specified line is known.
1394
1395       ?L     True if the line number of the last line in the file is known.
1396
1397       ?m     True if there is more than one input file.
1398
1399       ?n     True if this is the first prompt in a new input file.
1400
1401       ?pX    True if the percent into the current input file, based  on  byte
1402              offsets, of the specified line is known.
1403
1404       ?PX    True  if  the percent into the current input file, based on line
1405              numbers, of the specified line is known.
1406
1407       ?s     Same as "?B".
1408
1409       ?x     True if there is a next input file  (that  is,  if  the  current
1410              input file is not the last one).
1411
1412       Any  characters  other  than  the  special  ones (question mark, colon,
1413       period, percent, and backslash) become literally part  of  the  prompt.
1414       Any  of  the special characters may be included in the prompt literally
1415       by preceding it with a backslash.
1416
1417       Some examples:
1418
1419       ?f%f:Standard input.
1420
1421       This prompt prints the filename, if known; otherwise the string  "Stan‐
1422       dard input".
1423
1424       ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
1425
1426       This  prompt  would print the filename, if known.  The filename is fol‐
1427       lowed by the line number, if known, otherwise  the  percent  if  known,
1428       otherwise  the  byte  offset  if  known.  Otherwise, a dash is printed.
1429       Notice how each question mark has a matching  period,  and  how  the  %
1430       after the %pt is included literally by escaping it with a backslash.
1431
1432       ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x..%t";
1433
1434       This  prints  the  filename if this is the first prompt in a file, fol‐
1435       lowed by the "file N of N" message if there  is  more  than  one  input
1436       file.   Then,  if  we are at end-of-file, the string "(END)" is printed
1437       followed by the name of the next file, if there is one.   Finally,  any
1438       trailing spaces are truncated.  This is the default prompt.  For refer‐
1439       ence, here are the defaults for  the  other  two  prompts  (-m  and  -M
1440       respectively).   Each  is  broken  into  two lines here for readability
1441       only.
1442
1443       ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x.:
1444            ?pB%pB\%:byte %bB?s/%s...%t
1445
1446       ?f%f .?n?m(%T %i of %m) ..?ltlines %lt-%lb?L/%L. :
1447            byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
1448
1449       And here is the default message produced by the = command:
1450
1451       ?f%f .?m(%T %i of %m) .?ltlines %lt-%lb?L/%L. .
1452            byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
1453
1454       The prompt expansion features are also used for another purpose: if  an
1455       environment  variable LESSEDIT is defined, it is used as the command to
1456       be executed when the v command is  invoked.   The  LESSEDIT  string  is
1457       expanded  in the same way as the prompt strings.  The default value for
1458       LESSEDIT is:
1459
1460            %E ?lm+%lm. %f
1461
1462       Note that this expands to the editor name, followed by a + and the line
1463       number,  followed by the file name.  If your editor does not accept the
1464       "+linenumber" syntax, or has other differences  in  invocation  syntax,
1465       the LESSEDIT variable can be changed to modify this default.
1466
1467

SECURITY

1469       When  the  environment  variable LESSSECURE is set to 1, less runs in a
1470       "secure" mode.  This means these features are disabled:
1471
1472              !      the shell command
1473
1474              |      the pipe command
1475
1476              :e     the examine command.
1477
1478              v      the editing command
1479
1480              s  -o  log files
1481
1482              -k     use of lesskey files
1483
1484              -t     use of tags files
1485
1486                     metacharacters in filenames, such as *
1487
1488                     filename completion (TAB, ^L)
1489
1490       Less can also be compiled to be permanently in "secure" mode.
1491
1492

COMPATIBILITY WITH MORE

1494       If the environment variable LESS_IS_MORE is set to 1, or if the program
1495       is  invoked via a file link named "more", less behaves (mostly) in con‐
1496       formance with the POSIX "more" command specification.   In  this  mode,
1497       less behaves differently in these ways:
1498
1499       The  -e  option  works  differently.  If the -e option is not set, less
1500       behaves as if the -e option were set.  If the -e option  is  set,  less
1501       behaves as if the -E option were set.
1502
1503       The  -m  option  works  differently.   If the -m option is not set, the
1504       medium prompt is used, and it is prefixed with the  string  "--More--".
1505       If the -m option is set, the short prompt is used.
1506
1507       The  -n  option acts like the -z option.  The normal behavior of the -n
1508       option is unavailable in this mode.
1509
1510       The parameter to the -p option is taken to be  a  less  command  rather
1511       than a search pattern.
1512
1513       The  LESS  environment  variable  is  ignored, and the MORE environment
1514       variable is used in its place.
1515
1516

ENVIRONMENT VARIABLES

1518       Environment variables may be specified either in the system environment
1519       as  usual,  or  in  a  lesskey  (1) file.  If environment variables are
1520       defined in more than one place, variables defined in  a  local  lesskey
1521       file  take precedence over variables defined in the system environment,
1522       which take precedence over variables defined in the system-wide lesskey
1523       file.
1524
1525       COLUMNS
1526              Sets the number of columns on the screen.  Takes precedence over
1527              the number of columns specified by the TERM variable.   (But  if
1528              you  have  a  windowing  system  which  supports  TIOCGWINSZ  or
1529              WIOCGETD, the window system's idea  of  the  screen  size  takes
1530              precedence over the LINES and COLUMNS environment variables.)
1531
1532       EDITOR The name of the editor (used for the v command).
1533
1534       HOME   Name  of  the user's home directory (used to find a lesskey file
1535              on Unix and OS/2 systems).
1536
1537       HOMEDRIVE, HOMEPATH
1538              Concatenation of the HOMEDRIVE and  HOMEPATH  environment  vari‐
1539              ables is the name of the user's home directory if the HOME vari‐
1540              able is not set (only in the Windows version).
1541
1542       INIT   Name of the user's init directory (used to find a  lesskey  file
1543              on OS/2 systems).
1544
1545       LANG   Language for determining the character set.
1546
1547       LC_CTYPE
1548              Language for determining the character set.
1549
1550       LESS   Options which are passed to less automatically.
1551
1552       LESSANSIENDCHARS
1553              Characters  which may end an ANSI color escape sequence (default
1554              "m").
1555
1556       LESSANSIMIDCHARS
1557              Characters which may appear between the ESC  character  and  the
1558              end   character  in  an  ANSI  color  escape  sequence  (default
1559              "0123456789:;[?!"'#%()*+ ".
1560
1561       LESSBINFMT
1562              Format for displaying non-printable, non-control characters.
1563
1564       LESSCHARDEF
1565              Defines a character set.
1566
1567       LESSCHARSET
1568              Selects a predefined character set.
1569
1570       LESSCLOSE
1571              Command line to invoke the (optional) input-postprocessor.
1572
1573       LESSECHO
1574              Name of the lessecho program (default "lessecho").  The lessecho
1575              program  is needed to expand metacharacters, such as * and ?, in
1576              filenames on Unix systems.
1577
1578       LESSEDIT
1579              Editor prototype string (used for the v command).   See  discus‐
1580              sion under PROMPTS.
1581
1582       LESSGLOBALTAGS
1583              Name  of  the command used by the -t option to find global tags.
1584              Normally should be set to "global" if your system has the global
1585              (1) command.  If not set, global tags are not used.
1586
1587       LESSHISTFILE
1588              Name  of  the  history file used to remember search commands and
1589              shell commands between invocations of less.  If set  to  "-"  or
1590              "/dev/null",  a  history  file  is  not  used.   The  default is
1591              "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst"  on  DOS  and
1592              Windows  systems,  or "$HOME/lesshst.ini" or "$INIT/lesshst.ini"
1593              on OS/2 systems.
1594
1595       LESSHISTSIZE
1596              The maximum number of commands to save in the history file.  The
1597              default is 100.
1598
1599       LESSKEY
1600              Name of the default lesskey(1) file.
1601
1602       LESSKEY_SYSTEM
1603              Name of the default system-wide lesskey(1) file.
1604
1605       LESSMETACHARS
1606              List  of characters which are considered "metacharacters" by the
1607              shell.
1608
1609       LESSMETAESCAPE
1610              Prefix which less will add before each metacharacter in  a  com‐
1611              mand  sent  to the shell.  If LESSMETAESCAPE is an empty string,
1612              commands containing metacharacters will not  be  passed  to  the
1613              shell.
1614
1615       LESSOPEN
1616              Command line to invoke the (optional) input-preprocessor.
1617
1618       LESSSECURE
1619              Runs less in "secure" mode.  See discussion under SECURITY.
1620
1621       LESSSEPARATOR
1622              String  to  be  appended to a directory name in filename comple‐
1623              tion.
1624
1625       LESSUTFBINFMT
1626              Format for displaying non-printable Unicode code points.
1627
1628       LESS_IS_MORE
1629              Emulate the more (1) command.
1630
1631       LINES  Sets the number of lines on the screen.  Takes  precedence  over
1632              the number of lines specified by the TERM variable.  (But if you
1633              have a windowing system which supports TIOCGWINSZ  or  WIOCGETD,
1634              the  window  system's  idea  of the screen size takes precedence
1635              over the LINES and COLUMNS environment variables.)
1636
1637       MORE   Options which are passed to less automatically when  running  in
1638              more compatible mode.
1639
1640       PATH   User's  search  path  (used to find a lesskey file on MS-DOS and
1641              OS/2 systems).
1642
1643       SHELL  The shell used to execute the ! command, as well  as  to  expand
1644              filenames.
1645
1646       TERM   The type of terminal on which less is being run.
1647
1648       VISUAL The name of the editor (used for the v command).
1649
1650

SEE ALSO

1652       lesskey(1)
1653
1654
1656       Copyright (C) 1984-2017  Mark Nudelman
1657
1658       less  is  part of the GNU project and is free software.  You can redis‐
1659       tribute it and/or modify it under the terms of either (1) the GNU  Gen‐
1660       eral  Public  License  as published by the Free Software Foundation; or
1661       (2) the Less License.  See the file README in the less distribution for
1662       more details regarding redistribution.  You should have received a copy
1663       of the GNU General Public License along with the source for  less;  see
1664       the  file  COPYING.   If not, write to the Free Software Foundation, 59
1665       Temple Place, Suite 330, Boston, MA  02111-1307, USA.  You should  also
1666       have received a copy of the Less License; see the file LICENSE.
1667
1668       less is distributed in the hope that it will be useful, but WITHOUT ANY
1669       WARRANTY; without even the implied warranty of MERCHANTABILITY or  FIT‐
1670       NESS  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
1671       more details.
1672
1673

AUTHOR

1675       Mark Nudelman
1676       Send bug reports or comments to <bug-less@gnu.org>
1677       See http://www.greenwoodsoftware.com/less/bugs.html for the latest list
1678       of known bugs in less.
1679       For more information, see the less homepage at
1680       http://www.greenwoodsoftware.com/less.
1681
1682
1683
1684                           Version 530: 05 Dec 2017                    LESS(1)
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