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

OPTIONS

405       Command line options are described below.  Most options may be  changed
406       while less is running, via the "-" command.
407
408       Most  options  may be given in one of two forms: either a dash followed
409       by a single letter, or two dashes followed by a long  option  name.   A
410       long  option  name  may  be  abbreviated as long as the abbreviation is
411       unambiguous.  For example, --quit-at-eof may be abbreviated --quit, but
412       not --qui, since both --quit-at-eof and --quiet begin with --qui.  Some
413       long option names are in uppercase, such as --QUIT-AT-EOF, as  distinct
414       from  --quit-at-eof.  Such option names need only have their first let‐
415       ter capitalized; the remainder of the name may be in either case.   For
416       example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.
417
418       Options are also taken from the environment variable "LESS".  For exam‐
419       ple, to avoid typing "less -options ..." each time less is invoked, you
420       might tell csh:
421
422       setenv LESS "-options"
423
424       or if you use sh:
425
426       LESS="-options"; export LESS
427
428       On  MS-DOS,  you don't need the quotes, but you should replace any per‐
429       cent signs in the options string by double percent signs.
430
431       The environment variable is parsed before the command line, so  command
432       line  options  override  the  LESS  environment variable.  If an option
433       appears in the LESS variable, it can be reset to its default  value  on
434       the command line by beginning the command line option with "-+".
435
436       For  options like -P or -D which take a following string, a dollar sign
437       ($) must be used to signal the end of the string.  For example, to  set
438       two  -D  options  on  MS-DOS, you must have a dollar sign between them,
439       like this:
440
441       LESS="-Dn9.1$-Ds4.1"
442
443
444       -? or --help
445              This option displays a summary of the commands accepted by  less
446              (the  same  as  the  h  command).   (Depending on how your shell
447              interprets the question mark, it may be necessary to  quote  the
448              question mark, thus: "-\?".)
449
450       -a or --search-skip-screen
451              Causes  searches  to  start after the last line displayed on the
452              screen, thus skipping all lines displayed  on  the  screen.   By
453              default,  searches  start  at  the second line on the screen (or
454              after the last found line; see the -j option).
455
456       -bn or --buffers=n
457              Specifies the amount of buffer space  less  will  use  for  each
458              file,  in  units  of  kilobytes (1024 bytes).  By default 64K of
459              buffer space is used for each file (unless the file is  a  pipe;
460              see  the  -B  option).   The  -b option specifies instead that n
461              kilobytes of buffer space should be used for each file.  If n is
462              -1,  buffer  space is unlimited; that is, the entire file can be
463              read into memory.
464
465       -B or --auto-buffers
466              By default, when data is read from a pipe, buffers are allocated
467              automatically as needed.  If a large amount of data is read from
468              the pipe, this can cause a large amount of memory  to  be  allo‐
469              cated.  The -B option disables this automatic allocation of buf‐
470              fers for pipes, so that only 64K (or the amount of space  speci‐
471              fied by the -b option) is used for the pipe.  Warning: use of -B
472              can result in erroneous display, since only  the  most  recently
473              viewed  part  of  the  piped data is kept in memory; any earlier
474              data is lost.
475
476       -c or --clear-screen
477              Causes full screen repaints to be  painted  from  the  top  line
478              down.   By  default,  full screen repaints are done by scrolling
479              from the bottom of the screen.
480
481       -C or --CLEAR-SCREEN
482              Same as -c, for compatibility with older versions of less.
483
484       -d or --dumb
485              The -d option suppresses the error message normally displayed if
486              the  terminal is dumb; that is, lacks some important capability,
487              such as the ability to clear the screen or scroll backward.  The
488              -d  option  does  not otherwise change the behavior of less on a
489              dumb terminal.
490
491       -Dxcolor or --color=xcolor
492              [MS-DOS only] Sets the color of the text displayed.  x is a sin‐
493              gle  character  which  selects  the  type of text whose color is
494              being set: n=normal, s=standout, d=bold, u=underlined,  k=blink.
495              color  is  a  pair  of numbers separated by a period.  The first
496              number selects the foreground color and the second  selects  the
497              background  color of the text.  A single number N is the same as
498              N.M, where M is the normal background color.
499
500
501       -e or --quit-at-eof
502              Causes less to automatically exit the  second  time  it  reaches
503              end-of-file.   By  default, the only way to exit less is via the
504              "q" command.
505
506       -E or --QUIT-AT-EOF
507              Causes less to automatically exit the first time it reaches end-
508              of-file.
509
510       -f or --force
511              Forces non-regular files to be opened.  (A non-regular file is a
512              directory or a device special file.)  Also suppresses the  warn‐
513              ing message when a binary file is opened.  By default, less will
514              refuse to open non-regular files.  Note that some operating sys‐
515              tems will not allow directories to be read, even if -f is set.
516
517       -F or --quit-if-one-screen
518              Causes less to automatically exit if the entire file can be dis‐
519              played on the first screen.
520
521       -g or --hilite-search
522              Normally, less will highlight ALL strings which match  the  last
523              search  command.   The  -g option changes this behavior to high‐
524              light only the particular string which was  found  by  the  last
525              search command.  This can cause less to run somewhat faster than
526              the default.
527
528       -G or --HILITE-SEARCH
529              The -G option suppresses all highlighting of  strings  found  by
530              search commands.
531
532       --old-bot
533              Reverts to the old bottom of screen behavior.  This can be some‐
534              times desirable  if  the  long lines are not wrapped   correctly
535              when  reaching  the  bottom  of  the  terminal,  while scrolling
536              forward.
537
538       -hn or --max-back-scroll=n
539              Specifies a maximum number of lines to scroll backward.   If  it
540              is necessary to scroll backward more than n lines, the screen is
541              repainted in a forward direction instead.  (If the terminal does
542              not have the ability to scroll backward, -h0 is implied.)
543
544       -i or --ignore-case
545              Causes searches to ignore case; that is, uppercase and lowercase
546              are considered identical.  This option is ignored if any  upper‐
547              case  letters appear in the search pattern; in other words, if a
548              pattern contains uppercase letters, then that  search  does  not
549              ignore case.
550
551       -I or --IGNORE-CASE
552              Like  -i,  but searches ignore case even if the pattern contains
553              uppercase letters.
554
555       -jn or --jump-target=n
556              Specifies a line on the screen where the "target" line is to  be
557              positioned.   The  target line is the line specified by any com‐
558              mand to search for a pattern, jump to a line number, jump  to  a
559              file percentage or jump to a tag.  The screen line may be speci‐
560              fied by a number: the top line on the screen is 1, the  next  is
561              2, and so on.  The number may be negative to specify a line rel‐
562              ative to the bottom of the screen: the bottom line on the screen
563              is  -1, the second to the bottom is -2, and so on.  Alternately,
564              the screen line may be specified as a fraction of the height  of
565              the  screen,  starting with a decimal point: .5 is in the middle
566              of the screen, .3 is three tenths down from the first line,  and
567              so  on.  If the line is specified as a fraction, the actual line
568              number is recalculated if the terminal  window  is  resized,  so
569              that  the  target  line remains at the specified fraction of the
570              screen height.  If any form of the -j option  is  used,  forward
571              searches  begin  at  the line immediately after the target line,
572              and backward searches begin at the target line.  For example, if
573              "-j4" is used, the target line is the fourth line on the screen,
574              so forward searches begin at the fifth line on the screen.
575
576       -J or --status-column
577              Displays a status column at the left edge of  the  screen.   The
578              status  column  shows the lines that matched the current search.
579              The status column is also used if the -w  or  -W  option  is  in
580              effect.
581
582       -kfilename or --lesskey-file=filename
583              Causes  less  to  open and interpret the named file as a lesskey
584              (1) file.  Multiple -k options may be specified.  If the LESSKEY
585              or  LESSKEY_SYSTEM  environment variable is set, or if a lesskey
586              file is found in a standard place (see KEY BINDINGS), it is also
587              used as a lesskey file.
588
589       -K or --quit-on-intr
590              Causes  less  to  exit  immediately  when an interrupt character
591              (usually ^C) is typed.  Normally, an interrupt character  causes
592              less  to  stop  whatever  it  is doing and return to its command
593              prompt.  Note that use of this option  makes  it  impossible  to
594              return to the command prompt from the "F" command.
595
596       -L or --no-lessopen
597              Ignore  the  LESSOPEN  environment  variable (see the INPUT PRE‐
598              PROCESSOR section below).  This option can be  set  from  within
599              less,  but  it will apply only to files opened subsequently, not
600              to the file which is currently open.
601
602       -m or --long-prompt
603              Causes less to prompt verbosely (like more),  with  the  percent
604              into the file.  By default, less prompts with a colon.
605
606       -M or --LONG-PROMPT
607              Causes less to prompt even more verbosely than more.
608
609       -n or --line-numbers
610              Suppresses  line numbers.  The default (to use line numbers) may
611              cause less to run more slowly in some cases, especially  with  a
612              very  large  input  file.   Suppressing line numbers with the -n
613              option will avoid this problem.  Using line numbers  means:  the
614              line number will be displayed in the verbose prompt and in the =
615              command, and the v command will pass the current line number  to
616              the  editor  (see  also  the  discussion  of LESSEDIT in PROMPTS
617              below).
618
619       -N or --LINE-NUMBERS
620              Causes a line number to be displayed at the  beginning  of  each
621              line in the display.
622
623       -ofilename or --log-file=filename
624              Causes  less  to copy its input to the named file as it is being
625              viewed.  This applies only when the input file is a pipe, not an
626              ordinary  file.   If  the file already exists, less will ask for
627              confirmation before overwriting it.
628
629       -Ofilename or --LOG-FILE=filename
630              The -O option is like -o, but it will overwrite an existing file
631              without asking for confirmation.
632
633              If  no log file has been specified, the -o and -O options can be
634              used from within less to specify a log  file.   Without  a  file
635              name, they will simply report the name of the log file.  The "s"
636              command is equivalent to specifying -o from within less.
637
638       -ppattern or --pattern=pattern
639              The -p option on the command line is  equivalent  to  specifying
640              +/pattern;  that  is, it tells less to start at the first occur‐
641              rence of pattern in the file.
642
643       -Pprompt or --prompt=prompt
644              Provides a way to tailor the three prompt  styles  to  your  own
645              preference.  This option would normally be put in the LESS envi‐
646              ronment variable, rather than being typed in with each less com‐
647              mand.  Such an option must either be the last option in the LESS
648              variable, or be terminated by a dollar sign.  -Ps followed by  a
649              string  changes  the default (short) prompt to that string.  -Pm
650              changes the medium (-m)  prompt.   -PM  changes  the  long  (-M)
651              prompt.   -Ph  changes  the  prompt  for  the  help screen.  -P=
652              changes the message printed by the = command.  -Pw  changes  the
653              message  printed while waiting for data (in the F command).  All
654              prompt strings consist of a  sequence  of  letters  and  special
655              escape sequences.  See the section on PROMPTS for more details.
656
657       -q or --quiet or --silent
658              Causes  moderately  "quiet"  operation: the terminal bell is not
659              rung if an attempt is made to scroll past the end of the file or
660              before the beginning of the file.  If the terminal has a "visual
661              bell", it is used instead.  The bell will  be  rung  on  certain
662              other  errors, such as typing an invalid character.  The default
663              is to ring the terminal bell in all such cases.
664
665       -Q or --QUIET or --SILENT
666              Causes totally "quiet" operation: the  terminal  bell  is  never
667              rung.
668
669       -r or --raw-control-chars
670              Causes "raw" control characters to be displayed.  The default is
671              to display control characters  using  the  caret  notation;  for
672              example, a control-A (octal 001) is displayed as "^A".  Warning:
673              when the -r option is used, less cannot keep track of the actual
674              appearance  of  the screen (since this depends on how the screen
675              responds to each type of control character).  Thus, various dis‐
676              play  problems may result, such as long lines being split in the
677              wrong place.
678
679       -R or --RAW-CONTROL-CHARS
680              Like -r, but only ANSI "color" escape sequences  are  output  in
681              "raw" form.  Unlike -r, the screen appearance is maintained cor‐
682              rectly  in  most  cases.   ANSI  "color"  escape  sequences  are
683              sequences of the form:
684
685                   ESC [ ... m
686
687              where  the  "..." is zero or more color specification characters
688              For the purpose of keeping  track  of  screen  appearance,  ANSI
689              color  escape sequences are assumed to not move the cursor.  You
690              can make less think that characters other than "m" can end  ANSI
691              color  escape  sequences  by  setting  the  environment variable
692              LESSANSIENDCHARS to the list of characters which can end a color
693              escape  sequence.   And  you can make less think that characters
694              other than the standard ones may appear between the ESC and  the
695              m  by  setting  the environment variable LESSANSIMIDCHARS to the
696              list of characters which can appear.
697
698       -s or --squeeze-blank-lines
699              Causes consecutive blank lines to  be  squeezed  into  a  single
700              blank line.  This is useful when viewing nroff output.
701
702       -S or --chop-long-lines
703              Causes  lines  longer than the screen width to be chopped rather
704              than folded.  That is, the portion of a long line that does  not
705              fit  in  the  screen width is not shown.  The default is to fold
706              long lines; that is, display the remainder on the next line.
707
708       -ttag or --tag=tag
709              The -t option, followed immediately by a TAG, will edit the file
710              containing  that tag.  For this to work, tag information must be
711              available; for example, there may  be  a  file  in  the  current
712              directory called "tags", which was previously built by ctags (1)
713              or an equivalent command.  If the environment variable LESSGLOB‐
714              ALTAGS  is set, it is taken to be the name of a command compati‐
715              ble with global (1), and that command is executed  to  find  the
716              tag.  (See http://www.gnu.org/software/global/global.html).  The
717              -t option may also be specified from within less  (using  the  -
718              command)  as a way of examining a new file.  The command ":t" is
719              equivalent to specifying -t from within less.
720
721       -Ttagsfile or --tag-file=tagsfile
722              Specifies a tags file to be used instead of "tags".
723
724       -u or --underline-special
725              Causes backspaces and carriage returns to be treated  as  print‐
726              able  characters;  that  is,  they are sent to the terminal when
727              they appear in the input.
728
729       -U or --UNDERLINE-SPECIAL
730              Causes backspaces, tabs and carriage returns to  be  treated  as
731              control  characters;  that  is, they are handled as specified by
732              the -r option.
733
734              By default, if neither -u nor  -U  is  given,  backspaces  which
735              appear  adjacent  to  an  underscore  character are treated spe‐
736              cially: the underlined text is displayed  using  the  terminal's
737              hardware  underlining capability.  Also, backspaces which appear
738              between two identical  characters  are  treated  specially:  the
739              overstruck  text  is printed using the terminal's hardware bold‐
740              face capability.  Other backspaces are deleted, along  with  the
741              preceding character.  Carriage returns immediately followed by a
742              newline are deleted.  other  carriage  returns  are  handled  as
743              specified  by the -r option.  Text which is overstruck or under‐
744              lined can be searched for if neither -u nor -U is in effect.
745
746       -V or --version
747              Displays the version number of less.
748
749       -w or --hilite-unread
750              Temporarily highlights the first  "new"  line  after  a  forward
751              movement of a full page.  The first "new" line is the line imme‐
752              diately following the line  previously  at  the  bottom  of  the
753              screen.  Also highlights the target line after a g or p command.
754              The highlight is removed at the next command which causes  move‐
755              ment.   The  entire line is highlighted, unless the -J option is
756              in effect, in which case only the status column is highlighted.
757
758       -W or --HILITE-UNREAD
759              Like -w, but temporarily highlights the first new line after any
760              forward movement command larger than one line.
761
762       -xn,... or --tabs=n,...
763              Sets  tab  stops.  If only one n is specified, tab stops are set
764              at multiples of n.  If multiple values separated by  commas  are
765              specified,  tab  stops are set at those positions, and then con‐
766              tinue with the same spacing  as  the  last  two.   For  example,
767              -x9,17  will  set  tabs  at  positions  9, 17, 25, 33, etc.  The
768              default for n is 8.
769
770       -X or --no-init
771              Disables sending the termcap initialization and deinitialization
772              strings  to  the  terminal.   This is sometimes desirable if the
773              deinitialization string does something unnecessary, like  clear‐
774              ing the screen.
775
776       -yn or --max-forw-scroll=n
777              Specifies a maximum number of lines to scroll forward.  If it is
778              necessary to scroll forward more than n  lines,  the  screen  is
779              repainted  instead.   The -c or -C option may be used to repaint
780              from the top of the screen if desired.  By default, any  forward
781              movement causes scrolling.
782
783       -[z]n or --window=n
784              Changes  the  default  scrolling  window  size  to n lines.  The
785              default is one screenful.  The z and w commands can also be used
786              to  change the window size.  The "z" may be omitted for compati‐
787              bility with some versions of more.  If the number n is negative,
788              it  indicates  n  lines  less than the current screen size.  For
789              example, if the screen is 24 lines, -z-4 sets the scrolling win‐
790              dow  to  20  lines.   If  the screen is resized to 40 lines, the
791              scrolling window automatically changes to 36 lines.
792
793       -"cc or --quotes=cc
794              Changes the filename quoting character.  This may  be  necessary
795              if  you are trying to name a file which contains both spaces and
796              quote characters.  Followed by a single character, this  changes
797              the  quote  character to that character.  Filenames containing a
798              space should then be surrounded by that character rather than by
799              double  quotes.   Followed  by  two characters, changes the open
800              quote to the first character, and the close quote to the  second
801              character.  Filenames containing a space should then be preceded
802              by the open quote character and  followed  by  the  close  quote
803              character.   Note  that  even  after  the  quote  characters are
804              changed, this option remains -" (a dash  followed  by  a  double
805              quote).
806
807       -~ or --tilde
808              Normally lines after end of file are displayed as a single tilde
809              (~).  This option causes lines after end of file to be displayed
810              as blank lines.
811
812       -# or --shift
813              Specifies the default number of positions to scroll horizontally
814              in the RIGHTARROW and LEFTARROW commands.  If the number  speci‐
815              fied  is  zero,  it  sets the default number of positions to one
816              half of the screen width.  Alternately, the number may be speci‐
817              fied  as  a fraction of the width of the screen, starting with a
818              decimal point: .5 is half of  the  screen  width,  .3  is  three
819              tenths  of the screen width, and so on.  If the number is speci‐
820              fied as a fraction, the actual number  of  scroll  positions  is
821              recalculated  if  the  terminal  window  is resized, so that the
822              actual scroll remains at the specified fraction  of  the  screen
823              width.
824
825       --no-keypad
826              Disables  sending the keypad initialization and deinitialization
827              strings to the terminal.  This is sometimes useful if the keypad
828              strings make the numeric keypad behave in an undesirable manner.
829
830       --follow-name
831              Normally,  if  the  input  file is renamed while an F command is
832              executing, less will continue to display  the  contents  of  the
833              original  file  despite  its  name  change.  If --follow-name is
834              specified, during an F command less will periodically attempt to
835              reopen the file by name.  If the reopen succeeds and the file is
836              a different file from the original (which means that a new  file
837              has  been  created  with  the  same  name  as  the original (now
838              renamed) file), less will display the contents of that new file.
839
840       --     A command line argument of "--" marks the end  of  option  argu‐
841              ments.   Any  arguments  following this are interpreted as file‐
842              names.  This can be useful when viewing a file whose name begins
843              with a "-" or "+".
844
845       +      If  a  command  line option begins with +, the remainder of that
846              option is taken to be an initial command to less.  For  example,
847              +G  tells  less  to start at the end of the file rather than the
848              beginning, and +/xyz tells it to start at the  first  occurrence
849              of  "xyz"  in  the file.  As a special case, +<number> acts like
850              +<number>g; that is, it starts the display at the specified line
851              number  (however,  see  the caveat under the "g" command above).
852              If the option starts with ++, the  initial  command  applies  to
853              every  file being viewed, not just the first one.  The + command
854              described previously may also be used to set (or change) an ini‐
855              tial command for every file.
856
857

LINE EDITING

859       When  entering command line at the bottom of the screen (for example, a
860       filename for the :e command, or the pattern for a search command), cer‐
861       tain  keys  can  be used to manipulate the command line.  Most commands
862       have an alternate form in [ brackets ] which can be used if a key  does
863       not  exist  on  a  particular keyboard.  (Note that the forms beginning
864       with ESC do not work in some MS-DOS and Windows systems because ESC  is
865       the  line  erase  character.)  Any of these special keys may be entered
866       literally by preceding it with the "literal" character,  either  ^V  or
867       ^A.   A  backslash itself may also be entered literally by entering two
868       backslashes.
869
870       LEFTARROW [ ESC-h ]
871              Move the cursor one space to the left.
872
873       RIGHTARROW [ ESC-l ]
874              Move the cursor one space to the right.
875
876       ^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
877              (That is, CONTROL and LEFTARROW simultaneously.)  Move the  cur‐
878              sor one word to the left.
879
880       ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
881              (That is, CONTROL and RIGHTARROW simultaneously.)  Move the cur‐
882              sor one word to the right.
883
884       HOME [ ESC-0 ]
885              Move the cursor to the beginning of the line.
886
887       END [ ESC-$ ]
888              Move the cursor to the end of the line.
889
890       BACKSPACE
891              Delete the character to the left of the cursor,  or  cancel  the
892              command if the command line is empty.
893
894       DELETE or [ ESC-x ]
895              Delete the character under the cursor.
896
897       ^BACKSPACE [ ESC-BACKSPACE ]
898              (That  is,  CONTROL  and  BACKSPACE simultaneously.)  Delete the
899              word to the left of the cursor.
900
901       ^DELETE [ ESC-X or ESC-DELETE ]
902              (That is, CONTROL and DELETE simultaneously.)  Delete  the  word
903              under the cursor.
904
905       UPARROW [ ESC-k ]
906              Retrieve the previous command line.
907
908       DOWNARROW [ ESC-j ]
909              Retrieve the next command line.
910
911       TAB    Complete  the partial filename to the left of the cursor.  If it
912              matches more than one filename, the first match is entered  into
913              the  command  line.   Repeated  TABs  will  cycle thru the other
914              matching filenames.  If the completed filename is a directory, a
915              "/"  is  appended to the filename.  (On MS-DOS systems, a "\" is
916              appended.)  The environment variable LESSSEPARATOR can  be  used
917              to specify a different character to append to a directory name.
918
919       BACKTAB [ ESC-TAB ]
920              Like, TAB, but cycles in the reverse direction thru the matching
921              filenames.
922
923       ^L     Complete the partial filename to the left of the cursor.  If  it
924              matches more than one filename, all matches are entered into the
925              command line (if they fit).
926
927       ^U (Unix and OS/2) or ESC (MS-DOS)
928              Delete the entire command line, or cancel  the  command  if  the
929              command line is empty.  If you have changed your line-kill char‐
930              acter in Unix to something other than ^U, that character is used
931              instead of ^U.
932
933

KEY BINDINGS

935       You  may define your own less commands by using the program lesskey (1)
936       to create a lesskey file.  This file specifies a set  of  command  keys
937       and  an  action  associated with each key.  You may also use lesskey to
938       change the line-editing keys (see LINE EDITING), and to set environment
939       variables.   If the environment variable LESSKEY is set, less uses that
940       as the name of the lesskey file.  Otherwise, less looks in  a  standard
941       place  for  the lesskey file: On Unix systems, less looks for a lesskey
942       file called "$HOME/.less".  On MS-DOS and Windows systems,  less  looks
943       for  a lesskey file called "$HOME/_less", and if it is not found there,
944       then looks for a lesskey file called "_less" in any directory specified
945       in  the  PATH  environment variable.  On OS/2 systems, less looks for a
946       lesskey file called "$HOME/less.ini", and if  it  is  not  found,  then
947       looks  for  a lesskey file called "less.ini" in any directory specified
948       in the INIT environment variable, and if it not found there, then looks
949       for  a lesskey file called "less.ini" in any directory specified in the
950       PATH environment variable.   See  the  lesskey  manual  page  for  more
951       details.
952
953       A  system-wide lesskey file may also be set up to provide key bindings.
954       If a key is defined in both a local lesskey file and in the system-wide
955       file,  key bindings in the local file take precedence over those in the
956       system-wide file.  If the environment variable LESSKEY_SYSTEM  is  set,
957       less uses that as the name of the system-wide lesskey file.  Otherwise,
958       less looks in a standard place for the  system-wide  lesskey  file:  On
959       Unix  systems,  the system-wide lesskey file is /usr/local/etc/sysless.
960       (However, if less was built with a  different  sysconf  directory  than
961       /usr/local/etc, that directory is where the sysless file is found.)  On
962       MS-DOS and Windows systems, the system-wide lesskey  file  is  c:\_sys‐
963       less.  On OS/2 systems, the system-wide lesskey file is c:\sysless.ini.
964
965

INPUT PREPROCESSOR

967       You  may  define an "input preprocessor" for less.  Before less opens a
968       file, it first gives your input preprocessor a chance to modify the way
969       the  contents of the file are displayed.  An input preprocessor is sim‐
970       ply an executable program (or shell script), which writes the  contents
971       of the file to a different file, called the replacement file.  The con‐
972       tents of the replacement file are then displayed in place of  the  con‐
973       tents  of the original file.  However, it will appear to the user as if
974       the original file is opened; that is, less will  display  the  original
975       filename as the name of the current file.
976
977       An  input preprocessor receives one command line argument, the original
978       filename, as entered by the user.  It  should  create  the  replacement
979       file,  and when finished, print the name of the replacement file to its
980       standard output.  If the input preprocessor does not output a  replace‐
981       ment  filename, less uses the original file, as normal.  The input pre‐
982       processor is not called when viewing standard  input.   To  set  up  an
983       input  preprocessor, set the LESSOPEN environment variable to a command
984       line which will invoke your  input  preprocessor.   This  command  line
985       should  include  one  occurrence  of  the  string  "%s",  which will be
986       replaced by  the  filename  when  the  input  preprocessor  command  is
987       invoked.
988
989       When less closes a file opened in such a way, it will call another pro‐
990       gram, called the input postprocessor, which  may  perform  any  desired
991       clean-up  action  (such  as  deleting  the  replacement file created by
992       LESSOPEN).  This program receives two command line arguments, the orig‐
993       inal  filename  as entered by the user, and the name of the replacement
994       file.  To set up an input postprocessor, set the LESSCLOSE  environment
995       variable  to a command line which will invoke your input postprocessor.
996       It may include two  occurrences  of  the  string  "%s";  the  first  is
997       replaced  with  the  original  name of the file and the second with the
998       name of the replacement file, which was output by LESSOPEN.
999
1000       For example, on many Unix systems, these two scripts will allow you  to
1001       keep files in compressed format, but still let less view them directly:
1002
1003       lessopen.sh:
1004            #! /bin/sh
1005            case "$1" in
1006            *.Z) uncompress -
1007                 if [ -s /tmp/less.$$ ]; then
1008                      echo /tmp/less.$$
1009                 else
1010                      rm -f /tmp/less.$$
1011                 fi
1012                 ;;
1013            esac
1014
1015       lessclose.sh:
1016            #! /bin/sh
1017            rm $2
1018
1019       To  use these scripts, put them both where they can be executed and set
1020       LESSOPEN="lessopen.sh %s",  and  LESSCLOSE="lessclose.sh %s %s".   More
1021       complex  LESSOPEN  and LESSCLOSE scripts may be written to accept other
1022       types of compressed files, and so on.
1023
1024       It is also possible to set up an input preprocessor to  pipe  the  file
1025       data  directly to less, rather than putting the data into a replacement
1026       file.  This avoids the need to decompress the entire file before start‐
1027       ing to view it.  An input preprocessor that works this way is called an
1028       input pipe.  An input pipe, instead of writing the name of  a  replace‐
1029       ment  file  on  its  standard output, writes the entire contents of the
1030       replacement file on its standard output.  If the input  pipe  does  not
1031       write  any characters on its standard output, then there is no replace‐
1032       ment file and less uses the original file, as normal.  To use an  input
1033       pipe,  make  the first character in the LESSOPEN environment variable a
1034       vertical bar (|) to signify that the input  preprocessor  is  an  input
1035       pipe.
1036
1037       For  example, on many Unix systems, this script will work like the pre‐
1038       vious example scripts:
1039
1040       lesspipe.sh:
1041            #! /bin/sh
1042            case "$1" in
1043            *.Z) uncompress -c $1  2>/dev/null
1044                 ;;
1045            *)   exit 1
1046                 ;;
1047            esac
1048            exit $?
1049
1050       To  use  this  script,  put  it  where  it  can  be  executed  and  set
1051       LESSOPEN="|lesspipe.sh %s".
1052
1053       The script should return zero if the output was valid and non-zero oth‐
1054       erwise, so less could detect even a valid  empty  output  (for  example
1055       while  uncompressing  gzipped empty file).  For backward-compatibility,
1056       this is not required by  default.  To  turn  this  functionality  there
1057       should  be another vertical bar (|) straight after the first one in the
1058       LESSOPEN environment variable, eg.  LESSOPEN="||lesspipe.sh %s".
1059
1060       When an input pipe is used, a LESSCLOSE postprocessor can be used,  but
1061       it is usually not necessary since there is no replacement file to clean
1062       up.  In this case, the replacement file name passed  to  the  LESSCLOSE
1063       postprocessor is "-".
1064
1065       For  compatibility with previous versions of less, the input preproces‐
1066       sor or pipe is not used if less is viewing standard input.  However, if
1067       the  first  character of LESSOPEN is a dash (-), the input preprocessor
1068       is used on standard input as well as other files.  In  this  case,  the
1069       dash  is  not  considered  to  be part of the preprocessor command.  If
1070       standard input is being viewed, the input preprocessor is passed a file
1071       name  consisting of a single dash.  Similarly, if the first two charac‐
1072       ters of LESSOPEN are vertical bar and dash (|-), the input pipe is used
1073       on standard input as well as other files.  Again, in this case the dash
1074       is not considered to be part of the input pipe command.
1075
1076

NATIONAL CHARACTER SETS

1078       There are three types of characters in the input file:
1079
1080       normal characters
1081              can be displayed directly to the screen.
1082
1083       control characters
1084              should not be displayed directly, but are expected to  be  found
1085              in ordinary text files (such as backspace and tab).
1086
1087       binary characters
1088              should  not  be  displayed  directly  and are not expected to be
1089              found in text files.
1090
1091       A "character set" is simply a description of which characters are to be
1092       considered  normal,  control,  and binary.  The LESSCHARSET environment
1093       variable may be used to select a character set.   Possible  values  for
1094       LESSCHARSET are:
1095
1096       ascii  BS,  TAB, NL, CR, and formfeed are control characters, all chars
1097              with values between 32 and 126 are normal, and  all  others  are
1098              binary.
1099
1100       iso8859
1101              Selects  an  ISO 8859 character set.  This is the same as ASCII,
1102              except characters between 160 and  255  are  treated  as  normal
1103              characters.
1104
1105       latin1 Same as iso8859.
1106
1107       latin9 Same as iso8859.
1108
1109       dos    Selects a character set appropriate for MS-DOS.
1110
1111       ebcdic Selects an EBCDIC character set.
1112
1113       IBM-1047
1114              Selects  an  EBCDIC  character set used by OS/390 Unix Services.
1115              This is the EBCDIC analogue of latin1.  You get similar  results
1116              by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
1117              environment.
1118
1119       koi8-r Selects a Russian character set.
1120
1121       next   Selects a character set appropriate for NeXT computers.
1122
1123       utf-8  Selects the UTF-8 encoding  of  the  ISO  10646  character  set.
1124              UTF-8  is  special  in that it supports multi-byte characters in
1125              the input file.  It is the  only  character  set  that  supports
1126              multi-byte characters.
1127
1128       windows
1129              Selects  a  character  set appropriate for Microsoft Windows (cp
1130              1251).
1131
1132       In rare cases, it may be desired to tailor less to use a character  set
1133       other  than the ones definable by LESSCHARSET.  In this case, the envi‐
1134       ronment variable LESSCHARDEF can be used to define a character set.  It
1135       should be set to a string where each character in the string represents
1136       one character in the character set.  The character "." is  used  for  a
1137       normal  character, "c" for control, and "b" for binary.  A decimal num‐
1138       ber may be used for repetition.   For  example,  "bccc4b."  would  mean
1139       character  0  is  binary,  1,  2  and  3 are control, 4, 5, 6 and 7 are
1140       binary, and 8 is normal.  All characters after the last are taken to be
1141       the  same  as  the  last,  so characters 9 through 255 would be normal.
1142       (This is an example, and does not necessarily represent any real  char‐
1143       acter set.)
1144
1145       This  table  shows the value of LESSCHARDEF which is equivalent to each
1146       of the possible values for LESSCHARSET:
1147
1148            ascii     8bcccbcc18b95.b
1149            dos       8bcccbcc12bc5b95.b.
1150            ebcdic    5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
1151                      9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
1152            IBM-1047  4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
1153                      191.b
1154            iso8859   8bcccbcc18b95.33b.
1155            koi8-r    8bcccbcc18b95.b128.
1156            latin1    8bcccbcc18b95.33b.
1157            next      8bcccbcc18b95.bb125.bb
1158
1159       If neither LESSCHARSET nor LESSCHARDEF is set, but any of  the  strings
1160       "UTF-8",  "UTF8",  "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or
1161       LANG environment variables, then the default character set is utf-8.
1162
1163       If that string is not found, but your  system  supports  the  setlocale
1164       interface,  less  will  use  setlocale  to determine the character set.
1165       setlocale is controlled by setting the  LANG  or  LC_CTYPE  environment
1166       variables.
1167
1168       Finally,  if the setlocale interface is also not available, the default
1169       character set is latin1.
1170
1171       Control and  binary  characters  are  displayed  in  standout  (reverse
1172       video).  Each such character is displayed in caret notation if possible
1173       (e.g. ^A for control-A).  Caret notation is used only if inverting  the
1174       0100 bit results in a normal printable character.  Otherwise, the char‐
1175       acter is displayed as a hex number in angle brackets.  This format  can
1176       be  changed by setting the LESSBINFMT environment variable.  LESSBINFMT
1177       may begin with a "*" and one character to select the display attribute:
1178       "*k"  is  blinking, "*d" is bold, "*u" is underlined, "*s" is standout,
1179       and "*n" is normal.  If LESSBINFMT does not begin with  a  "*",  normal
1180       attribute  is  assumed.   The remainder of LESSBINFMT is a string which
1181       may include one printf-style escape sequence (a % followed by x, X,  o,
1182       d,  etc.).   For  example, if LESSBINFMT is "*u[%x]", binary characters
1183       are displayed in underlined hexadecimal surrounded  by  brackets.   The
1184       default  if  no  LESSBINFMT  is  specified is "*s<%02X>".  Warning: the
1185       result of expanding the character via LESSBINFMT must be less  than  31
1186       characters.
1187
1188       When the character set is utf-8, the LESSUTFBINFMT environment variable
1189       acts similarly to LESSBINFMT but it applies to Unicode code points that
1190       were  successfully  decoded but are unsuitable for display (e.g., unas‐
1191       signed code points).  Its default  value  is  "<U+%04lX>".   Note  that
1192       LESSUTFBINFMT  and  LESSBINFMT  share  their  display attribute setting
1193       ("*x") so specifying one will affect both; LESSUTFBINFMT is read  after
1194       LESSBINFMT  so  its  setting,  if any, will have priority.  Problematic
1195       octets in a UTF-8 file (octets of a truncated  sequence,  octets  of  a
1196       complete  but  non-shortest  form  sequence,  illegal octets, and stray
1197       trailing octets) are displayed individually using LESSBINFMT so  as  to
1198       facilitate diagnostic of how the UTF-8 file is ill-formed.
1199
1200

PROMPTS

1202       The  -P option allows you to tailor the prompt to your preference.  The
1203       string given to the -P option replaces  the  specified  prompt  string.
1204       Certain characters in the string are interpreted specially.  The prompt
1205       mechanism is rather complicated to provide flexibility, but  the  ordi‐
1206       nary  user need not understand the details of constructing personalized
1207       prompt strings.
1208
1209       A percent sign followed by a single character is expanded according  to
1210       what the following character is:
1211
1212       %bX    Replaced  by the byte offset into the current input file.  The b
1213              is followed by a single character (shown as X above) which spec‐
1214              ifies  the line whose byte offset is to be used.  If the charac‐
1215              ter is a "t", the byte offset of the top line in the display  is
1216              used, an "m" means use the middle line, a "b" means use the bot‐
1217              tom line, a "B" means use the line just after the  bottom  line,
1218              and  a  "j"  means use the "target" line, as specified by the -j
1219              option.
1220
1221       %B     Replaced by the size of the current input file.
1222
1223       %c     Replaced by the column number of the text appearing in the first
1224              column of the screen.
1225
1226       %dX    Replaced  by  the  page number of a line in the input file.  The
1227              line to be used is determined by the X, as with the %b option.
1228
1229       %D     Replaced by the number of pages in the input  file,  or  equiva‐
1230              lently, the page number of the last line in the input file.
1231
1232       %E     Replaced  by the name of the editor (from the VISUAL environment
1233              variable, or the EDITOR environment variable if  VISUAL  is  not
1234              defined).  See the discussion of the LESSEDIT feature below.
1235
1236       %f     Replaced by the name of the current input file.
1237
1238       %i     Replaced  by  the index of the current file in the list of input
1239              files.
1240
1241       %lX    Replaced by the line number of a line in the  input  file.   The
1242              line to be used is determined by the X, as with the %b option.
1243
1244       %L     Replaced by the line number of the last line in the input file.
1245
1246       %m     Replaced by the total number of input files.
1247
1248       %pX    Replaced  by  the  percent into the current input file, based on
1249              byte offsets.  The line used is determined by the X as with  the
1250              %b option.
1251
1252       %PX    Replaced  by  the  percent into the current input file, based on
1253              line numbers.  The line used is determined by the X as with  the
1254              %b option.
1255
1256       %s     Same as %B.
1257
1258       %t     Causes  any  trailing spaces to be removed.  Usually used at the
1259              end of the string, but may appear anywhere.
1260
1261       %x     Replaced by the name of the next input file in the list.
1262
1263       If any item is unknown (for example, the file size if input is a pipe),
1264       a question mark is printed instead.
1265
1266       The  format  of  the  prompt string can be changed depending on certain
1267       conditions.  A question mark followed by a single character  acts  like
1268       an  "IF":  depending  on the following character, a condition is evalu‐
1269       ated.  If the condition is true, any characters following the  question
1270       mark  and  condition  character,  up  to  a period, are included in the
1271       prompt.  If the condition is false, such characters are  not  included.
1272       A  colon appearing between the question mark and the period can be used
1273       to establish an "ELSE": any characters between the colon and the period
1274       are  included  in  the string if and only if the IF condition is false.
1275       Condition characters (which follow a question mark) may be:
1276
1277       ?a     True if any characters have been included in the prompt so far.
1278
1279       ?bX    True if the byte offset of the specified line is known.
1280
1281       ?B     True if the size of current input file is known.
1282
1283       ?c     True if the text is horizontally shifted (%c is not zero).
1284
1285       ?dX    True if the page number of the specified line is known.
1286
1287       ?e     True if at end-of-file.
1288
1289       ?f     True if there is an input filename (that is, if input is  not  a
1290              pipe).
1291
1292       ?lX    True if the line number of the specified line is known.
1293
1294       ?L     True if the line number of the last line in the file is known.
1295
1296       ?m     True if there is more than one input file.
1297
1298       ?n     True if this is the first prompt in a new input file.
1299
1300       ?pX    True  if  the percent into the current input file, based on byte
1301              offsets, of the specified line is known.
1302
1303       ?PX    True if the percent into the current input file, based  on  line
1304              numbers, of the specified line is known.
1305
1306       ?s     Same as "?B".
1307
1308       ?x     True  if  there  is  a  next input file (that is, if the current
1309              input file is not the last one).
1310
1311       Any characters other than  the  special  ones  (question  mark,  colon,
1312       period,  percent,  and  backslash) become literally part of the prompt.
1313       Any of the special characters may be included in the  prompt  literally
1314       by preceding it with a backslash.
1315
1316       Some examples:
1317
1318       ?f%f:Standard input.
1319
1320       This  prompt prints the filename, if known; otherwise the string "Stan‐
1321       dard input".
1322
1323       ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
1324
1325       This prompt would print the filename, if known.  The filename  is  fol‐
1326       lowed  by  the  line  number, if known, otherwise the percent if known,
1327       otherwise the byte offset if known.   Otherwise,  a  dash  is  printed.
1328       Notice  how  each  question  mark  has a matching period, and how the %
1329       after the %pt is included literally by escaping it with a backslash.
1330
1331       ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t
1332
1333       This prints the filename if this is the first prompt in  a  file,  fol‐
1334       lowed  by  the  "file  N  of N" message if there is more than one input
1335       file.  Then, if we are at end-of-file, the string  "(END)"  is  printed
1336       followed  by  the name of the next file, if there is one.  Finally, any
1337       trailing spaces are truncated.  This is the default prompt.  For refer‐
1338       ence,  here  are  the  defaults  for  the  other two prompts (-m and -M
1339       respectively).  Each is broken into  two  lines  here  for  readability
1340       only.
1341
1342       ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
1343            ?pB%pB\%:byte %bB?s/%s...%t
1344
1345       ?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
1346            byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
1347
1348       And here is the default message produced by the = command:
1349
1350       ?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
1351            byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
1352
1353       The  prompt expansion features are also used for another purpose: if an
1354       environment variable LESSEDIT is defined, it is used as the command  to
1355       be  executed  when  the  v  command is invoked.  The LESSEDIT string is
1356       expanded in the same way as the prompt strings.  The default value  for
1357       LESSEDIT is:
1358
1359            %E ?lm+%lm. %f
1360
1361       Note that this expands to the editor name, followed by a + and the line
1362       number, followed by the file name.  If your editor does not accept  the
1363       "+linenumber"  syntax,  or  has other differences in invocation syntax,
1364       the LESSEDIT variable can be changed to modify this default.
1365
1366

SECURITY

1368       When the environment variable LESSSECURE is set to 1, less  runs  in  a
1369       "secure" mode.  This means these features are disabled:
1370
1371              !      the shell command
1372
1373              |      the pipe command
1374
1375              :e     the examine command.
1376
1377              v      the editing command
1378
1379              s  -o  log files
1380
1381              -k     use of lesskey files
1382
1383              -t     use of tags files
1384
1385                     metacharacters in filenames, such as *
1386
1387                     filename completion (TAB, ^L)
1388
1389       Less can also be compiled to be permanently in "secure" mode.
1390
1391

COMPATIBILITY WITH MORE

1393       If the environment variable LESS_IS_MORE is set to 1, or if the program
1394       is invoked via a file link named "more", less behaves (mostly) in  con‐
1395       formance  with  the  POSIX "more" command specification.  In this mode,
1396       less behaves differently in these ways:
1397
1398       The -e option works differently.  If the -e option  is  not  set,  less
1399       behaves  as  if  the -E option were set.  If the -e option is set, less
1400       behaves as if the -e and -F options were set.
1401
1402       The -m option works differently.  If the -m  option  is  not  set,  the
1403       medium  prompt  is used, and it is prefixed with the string "--More--".
1404       If the -m option is set, the short prompt is used.
1405
1406       The -n option acts like the -z option.  The normal behavior of  the  -n
1407       option is unavailable in this mode.
1408
1409       The  parameter  to  the  -p option is taken to be a less command rather
1410       than a search pattern.
1411
1412       The LESS environment variable is  ignored,  and  the  MORE  environment
1413       variable is used in its place.
1414
1415

ENVIRONMENT VARIABLES

1417       Environment variables may be specified either in the system environment
1418       as usual, or in a lesskey  (1)  file.   If  environment  variables  are
1419       defined  in  more  than one place, variables defined in a local lesskey
1420       file take precedence over variables defined in the system  environment,
1421       which take precedence over variables defined in the system-wide lesskey
1422       file.
1423
1424       COLUMNS
1425              Sets the number of columns on the screen.  Takes precedence over
1426              the  number  of columns specified by the TERM variable.  (But if
1427              you  have  a  windowing  system  which  supports  TIOCGWINSZ  or
1428              WIOCGETD,  the  window  system's  idea  of the screen size takes
1429              precedence over the LINES and COLUMNS environment variables.)
1430
1431       EDITOR The name of the editor (used for the v command).
1432
1433       HOME   Name of the user's home directory (used to find a  lesskey  file
1434              on Unix and OS/2 systems).
1435
1436       HOMEDRIVE, HOMEPATH
1437              Concatenation  of  the  HOMEDRIVE and HOMEPATH environment vari‐
1438              ables is the name of the user's home directory if the HOME vari‐
1439              able is not set (only in the Windows version).
1440
1441       INIT   Name  of  the user's init directory (used to find a lesskey file
1442              on OS/2 systems).
1443
1444       LANG   Language for determining the character set.
1445
1446       LC_CTYPE
1447              Language for determining the character set.
1448
1449       LESS   Options which are passed to less automatically.
1450
1451       LESSANSIENDCHARS
1452              Characters which may end an ANSI color escape sequence  (default
1453              "m").
1454
1455       LESSANSIMIDCHARS
1456              Characters  which  may  appear between the ESC character and the
1457              end  character  in  an  ANSI  color  escape  sequence   (default
1458              "0123456789;[?!"'#%()*+ ".
1459
1460       LESSBINFMT
1461              Format for displaying non-printable, non-control characters.
1462
1463       LESSCHARDEF
1464              Defines a character set.
1465
1466       LESSCHARSET
1467              Selects a predefined character set.
1468
1469       LESSCLOSE
1470              Command line to invoke the (optional) input-postprocessor.
1471
1472       LESSECHO
1473              Name of the lessecho program (default "lessecho").  The lessecho
1474              program is needed to expand metacharacters, such as * and ?,  in
1475              filenames on Unix systems.
1476
1477       LESSEDIT
1478              Editor  prototype  string (used for the v command).  See discus‐
1479              sion under PROMPTS.
1480
1481       LESSGLOBALTAGS
1482              Name of the command used by the -t option to find  global  tags.
1483              Normally should be set to "global" if your system has the global
1484              (1) command.  If not set, global tags are not used.
1485
1486       LESSHISTFILE
1487              Name of the history file used to remember  search  commands  and
1488              shell  commands  between  invocations of less.  If set to "-" or
1489              "/dev/null", a  history  file  is  not  used.   The  default  is
1490              "$HOME/.lesshst"  on  Unix  systems, "$HOME/_lesshst" on DOS and
1491              Windows systems, or "$HOME/lesshst.ini"  or  "$INIT/lesshst.ini"
1492              on OS/2 systems.
1493
1494       LESSHISTSIZE
1495              The maximum number of commands to save in the history file.  The
1496              default is 100.
1497
1498       LESSKEY
1499              Name of the default lesskey(1) file.
1500
1501       LESSKEY_SYSTEM
1502              Name of the default system-wide lesskey(1) file.
1503
1504       LESSMETACHARS
1505              List of characters which are considered "metacharacters" by  the
1506              shell.
1507
1508       LESSMETAESCAPE
1509              Prefix  which  less will add before each metacharacter in a com‐
1510              mand sent to the shell.  If LESSMETAESCAPE is an  empty  string,
1511              commands  containing  metacharacters  will  not be passed to the
1512              shell.
1513
1514       LESSOPEN
1515              Command line to invoke the (optional) input-preprocessor.
1516
1517       LESSSECURE
1518              Runs less in "secure" mode.  See discussion under SECURITY.
1519
1520       LESSSEPARATOR
1521              String to be appended to a directory name  in  filename  comple‐
1522              tion.
1523
1524       LESSUTFBINFMT
1525              Format for displaying non-printable Unicode code points.
1526
1527       LESS_IS_MORE
1528              Emulate the more (1) command.
1529
1530       LINES  Sets  the  number of lines on the screen.  Takes precedence over
1531              the number of lines specified by the TERM variable.  (But if you
1532              have  a  windowing system which supports TIOCGWINSZ or WIOCGETD,
1533              the window system's idea of the  screen  size  takes  precedence
1534              over the LINES and COLUMNS environment variables.)
1535
1536       PATH   User's  search  path  (used to find a lesskey file on MS-DOS and
1537              OS/2 systems).
1538
1539       SHELL  The shell used to execute the ! command, as well  as  to  expand
1540              filenames.
1541
1542       TERM   The type of terminal on which less is being run.
1543
1544       VISUAL The name of the editor (used for the v command).
1545
1546

SEE ALSO

1548       lesskey(1)
1549
1550
1552       Copyright (C) 1984-2009  Mark Nudelman
1553
1554       less  is  part of the GNU project and is free software.  You can redis‐
1555       tribute it and/or modify it under the terms of either (1) the GNU  Gen‐
1556       eral  Public  License  as published by the Free Software Foundation; or
1557       (2) the Less License.  See the file README in the less distribution for
1558       more details regarding redistribution.  You should have received a copy
1559       of the GNU General Public License along with the source for  less;  see
1560       the  file  COPYING.   If not, write to the Free Software Foundation, 59
1561       Temple Place, Suite 330, Boston, MA  02111-1307, USA.  You should  also
1562       have received a copy of the Less License; see the file LICENSE.
1563
1564       less is distributed in the hope that it will be useful, but WITHOUT ANY
1565       WARRANTY; without even the implied warranty of MERCHANTABILITY or  FIT‐
1566       NESS  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
1567       more details.
1568
1569

AUTHOR

1571       Mark Nudelman <markn@greenwoodsoftware.com>
1572       See http://www.greenwoodsoftware.com/less/bugs.html for the latest list
1573       of known bugs in less.
1574       Send bug reports or comments to the above address or to
1575       bug-less@gnu.org.
1576       For more information, see the less homepage at
1577       http://www.greenwoodsoftware.com/less.
1578
1579
1580
1581                           Version 436: 07 Jul 2009                    LESS(1)
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