1LESS(1) General Commands Manual LESS(1)
2
3
4
6 less - opposite of more
7
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
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
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
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
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
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
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 esac
1046
1047 To use this script, put it where it can be executed and set
1048 LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE
1049 postprocessor can be used, but it is usually not necessary since there
1050 is no replacement file to clean up. In this case, the replacement file
1051 name passed to the LESSCLOSE postprocessor is "-".
1052
1053 For compatibility with previous versions of less, the input preproces‐
1054 sor or pipe is not used if less is viewing standard input. However, if
1055 the first character of LESSOPEN is a dash (-), the input preprocessor
1056 is used on standard input as well as other files. In this case, the
1057 dash is not considered to be part of the preprocessor command. If
1058 standard input is being viewed, the input preprocessor is passed a file
1059 name consisting of a single dash. Similarly, if the first two charac‐
1060 ters of LESSOPEN are vertical bar and dash (|-), the input pipe is used
1061 on standard input as well as other files. Again, in this case the dash
1062 is not considered to be part of the input pipe command.
1063
1064
1066 There are three types of characters in the input file:
1067
1068 normal characters
1069 can be displayed directly to the screen.
1070
1071 control characters
1072 should not be displayed directly, but are expected to be found
1073 in ordinary text files (such as backspace and tab).
1074
1075 binary characters
1076 should not be displayed directly and are not expected to be
1077 found in text files.
1078
1079 A "character set" is simply a description of which characters are to be
1080 considered normal, control, and binary. The LESSCHARSET environment
1081 variable may be used to select a character set. Possible values for
1082 LESSCHARSET are:
1083
1084 ascii BS, TAB, NL, CR, and formfeed are control characters, all chars
1085 with values between 32 and 126 are normal, and all others are
1086 binary.
1087
1088 iso8859
1089 Selects an ISO 8859 character set. This is the same as ASCII,
1090 except characters between 160 and 255 are treated as normal
1091 characters.
1092
1093 latin1 Same as iso8859.
1094
1095 latin9 Same as iso8859.
1096
1097 dos Selects a character set appropriate for MS-DOS.
1098
1099 ebcdic Selects an EBCDIC character set.
1100
1101 IBM-1047
1102 Selects an EBCDIC character set used by OS/390 Unix Services.
1103 This is the EBCDIC analogue of latin1. You get similar results
1104 by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
1105 environment.
1106
1107 koi8-r Selects a Russian character set.
1108
1109 next Selects a character set appropriate for NeXT computers.
1110
1111 utf-8 Selects the UTF-8 encoding of the ISO 10646 character set.
1112 UTF-8 is special in that it supports multi-byte characters in
1113 the input file. It is the only character set that supports
1114 multi-byte characters.
1115
1116 windows
1117 Selects a character set appropriate for Microsoft Windows (cp
1118 1251).
1119
1120 In rare cases, it may be desired to tailor less to use a character set
1121 other than the ones definable by LESSCHARSET. In this case, the envi‐
1122 ronment variable LESSCHARDEF can be used to define a character set. It
1123 should be set to a string where each character in the string represents
1124 one character in the character set. The character "." is used for a
1125 normal character, "c" for control, and "b" for binary. A decimal num‐
1126 ber may be used for repetition. For example, "bccc4b." would mean
1127 character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are
1128 binary, and 8 is normal. All characters after the last are taken to be
1129 the same as the last, so characters 9 through 255 would be normal.
1130 (This is an example, and does not necessarily represent any real char‐
1131 acter set.)
1132
1133 This table shows the value of LESSCHARDEF which is equivalent to each
1134 of the possible values for LESSCHARSET:
1135
1136 ascii 8bcccbcc18b95.b
1137 dos 8bcccbcc12bc5b95.b.
1138 ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
1139 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
1140 IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
1141 191.b
1142 iso8859 8bcccbcc18b95.33b.
1143 koi8-r 8bcccbcc18b95.b128.
1144 latin1 8bcccbcc18b95.33b.
1145 next 8bcccbcc18b95.bb125.bb
1146
1147 If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings
1148 "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or
1149 LANG environment variables, then the default character set is utf-8.
1150
1151 If that string is not found, but your system supports the setlocale
1152 interface, less will use setlocale to determine the character set.
1153 setlocale is controlled by setting the LANG or LC_CTYPE environment
1154 variables.
1155
1156 Finally, if the setlocale interface is also not available, the default
1157 character set is latin1.
1158
1159 Control and binary characters are displayed in standout (reverse
1160 video). Each such character is displayed in caret notation if possible
1161 (e.g. ^A for control-A). Caret notation is used only if inverting the
1162 0100 bit results in a normal printable character. Otherwise, the char‐
1163 acter is displayed as a hex number in angle brackets. This format can
1164 be changed by setting the LESSBINFMT environment variable. LESSBINFMT
1165 may begin with a "*" and one character to select the display attribute:
1166 "*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout,
1167 and "*n" is normal. If LESSBINFMT does not begin with a "*", normal
1168 attribute is assumed. The remainder of LESSBINFMT is a string which
1169 may include one printf-style escape sequence (a % followed by x, X, o,
1170 d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters
1171 are displayed in underlined hexadecimal surrounded by brackets. The
1172 default if no LESSBINFMT is specified is "*s<%02X>". Warning: the
1173 result of expanding the character via LESSBINFMT must be less than 31
1174 characters.
1175
1176 When the character set is utf-8, the LESSUTFBINFMT environment variable
1177 acts similarly to LESSBINFMT but it applies to Unicode code points that
1178 were successfully decoded but are unsuitable for display (e.g., unas‐
1179 signed code points). Its default value is "<U+%04lX>". Note that
1180 LESSUTFBINFMT and LESSBINFMT share their display attribute setting
1181 ("*x") so specifying one will affect both; LESSUTFBINFMT is read after
1182 LESSBINFMT so its setting, if any, will have priority. Problematic
1183 octets in a UTF-8 file (octets of a truncated sequence, octets of a
1184 complete but non-shortest form sequence, illegal octets, and stray
1185 trailing octets) are displayed individually using LESSBINFMT so as to
1186 facilitate diagnostic of how the UTF-8 file is ill-formed.
1187
1188
1190 The -P option allows you to tailor the prompt to your preference. The
1191 string given to the -P option replaces the specified prompt string.
1192 Certain characters in the string are interpreted specially. The prompt
1193 mechanism is rather complicated to provide flexibility, but the ordi‐
1194 nary user need not understand the details of constructing personalized
1195 prompt strings.
1196
1197 A percent sign followed by a single character is expanded according to
1198 what the following character is:
1199
1200 %bX Replaced by the byte offset into the current input file. The b
1201 is followed by a single character (shown as X above) which spec‐
1202 ifies the line whose byte offset is to be used. If the charac‐
1203 ter is a "t", the byte offset of the top line in the display is
1204 used, an "m" means use the middle line, a "b" means use the bot‐
1205 tom line, a "B" means use the line just after the bottom line,
1206 and a "j" means use the "target" line, as specified by the -j
1207 option.
1208
1209 %B Replaced by the size of the current input file.
1210
1211 %c Replaced by the column number of the text appearing in the first
1212 column of the screen.
1213
1214 %dX Replaced by the page number of a line in the input file. The
1215 line to be used is determined by the X, as with the %b option.
1216
1217 %D Replaced by the number of pages in the input file, or equiva‐
1218 lently, the page number of the last line in the input file.
1219
1220 %E Replaced by the name of the editor (from the VISUAL environment
1221 variable, or the EDITOR environment variable if VISUAL is not
1222 defined). See the discussion of the LESSEDIT feature below.
1223
1224 %f Replaced by the name of the current input file.
1225
1226 %i Replaced by the index of the current file in the list of input
1227 files.
1228
1229 %lX Replaced by the line number of a line in the input file. The
1230 line to be used is determined by the X, as with the %b option.
1231
1232 %L Replaced by the line number of the last line in the input file.
1233
1234 %m Replaced by the total number of input files.
1235
1236 %pX Replaced by the percent into the current input file, based on
1237 byte offsets. The line used is determined by the X as with the
1238 %b option.
1239
1240 %PX Replaced by the percent into the current input file, based on
1241 line numbers. The line used is determined by the X as with the
1242 %b option.
1243
1244 %s Same as %B.
1245
1246 %t Causes any trailing spaces to be removed. Usually used at the
1247 end of the string, but may appear anywhere.
1248
1249 %x Replaced by the name of the next input file in the list.
1250
1251 If any item is unknown (for example, the file size if input is a pipe),
1252 a question mark is printed instead.
1253
1254 The format of the prompt string can be changed depending on certain
1255 conditions. A question mark followed by a single character acts like
1256 an "IF": depending on the following character, a condition is evalu‐
1257 ated. If the condition is true, any characters following the question
1258 mark and condition character, up to a period, are included in the
1259 prompt. If the condition is false, such characters are not included.
1260 A colon appearing between the question mark and the period can be used
1261 to establish an "ELSE": any characters between the colon and the period
1262 are included in the string if and only if the IF condition is false.
1263 Condition characters (which follow a question mark) may be:
1264
1265 ?a True if any characters have been included in the prompt so far.
1266
1267 ?bX True if the byte offset of the specified line is known.
1268
1269 ?B True if the size of current input file is known.
1270
1271 ?c True if the text is horizontally shifted (%c is not zero).
1272
1273 ?dX True if the page number of the specified line is known.
1274
1275 ?e True if at end-of-file.
1276
1277 ?f True if there is an input filename (that is, if input is not a
1278 pipe).
1279
1280 ?lX True if the line number of the specified line is known.
1281
1282 ?L True if the line number of the last line in the file is known.
1283
1284 ?m True if there is more than one input file.
1285
1286 ?n True if this is the first prompt in a new input file.
1287
1288 ?pX True if the percent into the current input file, based on byte
1289 offsets, of the specified line is known.
1290
1291 ?PX True if the percent into the current input file, based on line
1292 numbers, of the specified line is known.
1293
1294 ?s Same as "?B".
1295
1296 ?x True if there is a next input file (that is, if the current
1297 input file is not the last one).
1298
1299 Any characters other than the special ones (question mark, colon,
1300 period, percent, and backslash) become literally part of the prompt.
1301 Any of the special characters may be included in the prompt literally
1302 by preceding it with a backslash.
1303
1304 Some examples:
1305
1306 ?f%f:Standard input.
1307
1308 This prompt prints the filename, if known; otherwise the string "Stan‐
1309 dard input".
1310
1311 ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
1312
1313 This prompt would print the filename, if known. The filename is fol‐
1314 lowed by the line number, if known, otherwise the percent if known,
1315 otherwise the byte offset if known. Otherwise, a dash is printed.
1316 Notice how each question mark has a matching period, and how the %
1317 after the %pt is included literally by escaping it with a backslash.
1318
1319 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t
1320
1321 This prints the filename if this is the first prompt in a file, fol‐
1322 lowed by the "file N of N" message if there is more than one input
1323 file. Then, if we are at end-of-file, the string "(END)" is printed
1324 followed by the name of the next file, if there is one. Finally, any
1325 trailing spaces are truncated. This is the default prompt. For refer‐
1326 ence, here are the defaults for the other two prompts (-m and -M
1327 respectively). Each is broken into two lines here for readability
1328 only.
1329
1330 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
1331 ?pB%pB\%:byte %bB?s/%s...%t
1332
1333 ?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
1334 byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
1335
1336 And here is the default message produced by the = command:
1337
1338 ?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
1339 byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
1340
1341 The prompt expansion features are also used for another purpose: if an
1342 environment variable LESSEDIT is defined, it is used as the command to
1343 be executed when the v command is invoked. The LESSEDIT string is
1344 expanded in the same way as the prompt strings. The default value for
1345 LESSEDIT is:
1346
1347 %E ?lm+%lm. %f
1348
1349 Note that this expands to the editor name, followed by a + and the line
1350 number, followed by the file name. If your editor does not accept the
1351 "+linenumber" syntax, or has other differences in invocation syntax,
1352 the LESSEDIT variable can be changed to modify this default.
1353
1354
1356 When the environment variable LESSSECURE is set to 1, less runs in a
1357 "secure" mode. This means these features are disabled:
1358
1359 ! the shell command
1360
1361 | the pipe command
1362
1363 :e the examine command.
1364
1365 v the editing command
1366
1367 s -o log files
1368
1369 -k use of lesskey files
1370
1371 -t use of tags files
1372
1373 metacharacters in filenames, such as *
1374
1375 filename completion (TAB, ^L)
1376
1377 Less can also be compiled to be permanently in "secure" mode.
1378
1379
1381 If the environment variable LESS_IS_MORE is set to 1, or if the program
1382 is invoked via a file link named "more", less behaves (mostly) in con‐
1383 formance with the POSIX "more" command specification. In this mode,
1384 less behaves differently in these ways:
1385
1386 The -e option works differently. If the -e option is not set, less
1387 behaves as if the -E option were set. If the -e option is set, less
1388 behaves as if the -e and -F options were set.
1389
1390 The -m option works differently. If the -m option is not set, the
1391 medium prompt is used, and it is prefixed with the string "--More--".
1392 If the -m option is set, the short prompt is used.
1393
1394 The -n option acts like the -z option. The normal behavior of the -n
1395 option is unavailable in this mode.
1396
1397 The parameter to the -p option is taken to be a less command rather
1398 than a search pattern.
1399
1400 The LESS environment variable is ignored, and the MORE environment
1401 variable is used in its place.
1402
1403
1405 Environment variables may be specified either in the system environment
1406 as usual, or in a lesskey (1) file. If environment variables are
1407 defined in more than one place, variables defined in a local lesskey
1408 file take precedence over variables defined in the system environment,
1409 which take precedence over variables defined in the system-wide lesskey
1410 file.
1411
1412 COLUMNS
1413 Sets the number of columns on the screen. Takes precedence over
1414 the number of columns specified by the TERM variable. (But if
1415 you have a windowing system which supports TIOCGWINSZ or
1416 WIOCGETD, the window system's idea of the screen size takes
1417 precedence over the LINES and COLUMNS environment variables.)
1418
1419 EDITOR The name of the editor (used for the v command).
1420
1421 HOME Name of the user's home directory (used to find a lesskey file
1422 on Unix and OS/2 systems).
1423
1424 HOMEDRIVE, HOMEPATH
1425 Concatenation of the HOMEDRIVE and HOMEPATH environment vari‐
1426 ables is the name of the user's home directory if the HOME vari‐
1427 able is not set (only in the Windows version).
1428
1429 INIT Name of the user's init directory (used to find a lesskey file
1430 on OS/2 systems).
1431
1432 LANG Language for determining the character set.
1433
1434 LC_CTYPE
1435 Language for determining the character set.
1436
1437 LESS Options which are passed to less automatically.
1438
1439 LESSANSIENDCHARS
1440 Characters which may end an ANSI color escape sequence (default
1441 "m").
1442
1443 LESSANSIMIDCHARS
1444 Characters which may appear between the ESC character and the
1445 end character in an ANSI color escape sequence (default
1446 "0123456789;[?!"'#%()*+ ".
1447
1448 LESSBINFMT
1449 Format for displaying non-printable, non-control characters.
1450
1451 LESSCHARDEF
1452 Defines a character set.
1453
1454 LESSCHARSET
1455 Selects a predefined character set.
1456
1457 LESSCLOSE
1458 Command line to invoke the (optional) input-postprocessor.
1459
1460 LESSECHO
1461 Name of the lessecho program (default "lessecho"). The lessecho
1462 program is needed to expand metacharacters, such as * and ?, in
1463 filenames on Unix systems.
1464
1465 LESSEDIT
1466 Editor prototype string (used for the v command). See discus‐
1467 sion under PROMPTS.
1468
1469 LESSGLOBALTAGS
1470 Name of the command used by the -t option to find global tags.
1471 Normally should be set to "global" if your system has the global
1472 (1) command. If not set, global tags are not used.
1473
1474 LESSHISTFILE
1475 Name of the history file used to remember search commands and
1476 shell commands between invocations of less. If set to "-" or
1477 "/dev/null", a history file is not used. The default is
1478 "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and
1479 Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini"
1480 on OS/2 systems.
1481
1482 LESSHISTSIZE
1483 The maximum number of commands to save in the history file. The
1484 default is 100.
1485
1486 LESSKEY
1487 Name of the default lesskey(1) file.
1488
1489 LESSKEY_SYSTEM
1490 Name of the default system-wide lesskey(1) file.
1491
1492 LESSMETACHARS
1493 List of characters which are considered "metacharacters" by the
1494 shell.
1495
1496 LESSMETAESCAPE
1497 Prefix which less will add before each metacharacter in a com‐
1498 mand sent to the shell. If LESSMETAESCAPE is an empty string,
1499 commands containing metacharacters will not be passed to the
1500 shell.
1501
1502 LESSOPEN
1503 Command line to invoke the (optional) input-preprocessor.
1504
1505 LESSSECURE
1506 Runs less in "secure" mode. See discussion under SECURITY.
1507
1508 LESSSEPARATOR
1509 String to be appended to a directory name in filename comple‐
1510 tion.
1511
1512 LESSUTFBINFMT
1513 Format for displaying non-printable Unicode code points.
1514
1515 LESS_IS_MORE
1516 Emulate the more (1) command.
1517
1518 LINES Sets the number of lines on the screen. Takes precedence over
1519 the number of lines specified by the TERM variable. (But if you
1520 have a windowing system which supports TIOCGWINSZ or WIOCGETD,
1521 the window system's idea of the screen size takes precedence
1522 over the LINES and COLUMNS environment variables.)
1523
1524 PATH User's search path (used to find a lesskey file on MS-DOS and
1525 OS/2 systems).
1526
1527 SHELL The shell used to execute the ! command, as well as to expand
1528 filenames.
1529
1530 TERM The type of terminal on which less is being run.
1531
1532 VISUAL The name of the editor (used for the v command).
1533
1534
1536 lesskey(1)
1537
1538
1540 Copyright (C) 1984-2009 Mark Nudelman
1541
1542 less is part of the GNU project and is free software. You can redis‐
1543 tribute it and/or modify it under the terms of either (1) the GNU Gen‐
1544 eral Public License as published by the Free Software Foundation; or
1545 (2) the Less License. See the file README in the less distribution for
1546 more details regarding redistribution. You should have received a copy
1547 of the GNU General Public License along with the source for less; see
1548 the file COPYING. If not, write to the Free Software Foundation, 59
1549 Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should also
1550 have received a copy of the Less License; see the file LICENSE.
1551
1552 less is distributed in the hope that it will be useful, but WITHOUT ANY
1553 WARRANTY; without even the implied warranty of MERCHANTABILITY or FIT‐
1554 NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
1555 more details.
1556
1557
1559 Mark Nudelman <markn@greenwoodsoftware.com>
1560 See http://www.greenwoodsoftware.com/less/bugs.html for the latest list
1561 of known bugs in less.
1562 Send bug reports or comments to the above address or to
1563 bug-less@gnu.org.
1564 For more information, see the less homepage at
1565 http://www.greenwoodsoftware.com/less.
1566
1567
1568
1569 Version 436: 07 Jul 2009 LESS(1)