1LESS(1) General Commands Manual LESS(1)
2
6 less - opposite of more
7
9 less -?
10 less --help
11 less -V
12 less --version
13 less [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
14 [-b space] [-h lines] [-j line] [-k keyfile]
15 [-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
16 [-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
17 [-# shift] [+[+]cmd] [--] [filename]...
18 (See the OPTIONS section for alternate option syntax with long option
19 names.)
20
22 Less is a program similar to more(1), but which allows backward move‐
23 ment in the file as well as forward movement. Also, less does not have
24 to read the entire input file before starting, so with large input
25 files it starts up faster than text editors like vi(1). Less uses
26 termcap (or terminfo on some systems), so it can run on a variety of
27 terminals. There is even limited support for hardcopy terminals. (On
28 a hardcopy terminal, lines which should be printed at the top of the
29 screen are prefixed with a caret.)
30 Commands are based on both more and vi. Commands may be preceded by a
32 decimal number, called N in the descriptions below. The number is used
33 by some commands, as indicated.
34
36 In the following descriptions, ^X means control-X. ESC stands for the
37 ESCAPE key; for example ESC-v means the two character sequence "ES‐
38 CAPE", then "v".
39 h or H Help: display a summary of these commands. If you forget all
41 the other commands, remember this one.
42 SPACE or ^V or f or ^F
44 Scroll forward N lines, default one window (see option -z be‐
45 low). If N is more than the screen size, only the final screen‐
46 ful is displayed. Warning: some systems use ^V as a special
47 literalization character.
48 z Like SPACE, but if N is specified, it becomes the new window
50 size.
51 ESC-SPACE
53 Like SPACE, but scrolls a full screenful, even if it reaches
54 end-of-file in the process.
55 ENTER or RETURN or ^N or e or ^E or j or ^J
57 Scroll forward N lines, default 1. The entire N lines are dis‐
58 played, even if N is more than the screen size.
59 d or ^D
61 Scroll forward N lines, default one half of the screen size. If
62 N is specified, it becomes the new default for subsequent d and
63 u commands.
64 b or ^B or ESC-v
66 Scroll backward N lines, default one window (see option -z be‐
67 low). If N is more than the screen size, only the final screen‐
68 ful is displayed.
69 w Like ESC-v, but if N is specified, it becomes the new window
71 size.
72 y or ^Y or ^P or k or ^K
74 Scroll backward N lines, default 1. The entire N lines are dis‐
75 played, even if N is more than the screen size. Warning: some
76 systems use ^Y as a special job control character.
77 u or ^U
79 Scroll backward N lines, default one half of the screen size.
80 If N is specified, it becomes the new default for subsequent d
81 and u commands.
82 J Like j, but continues to scroll beyond the end of the file.
84 K or Y Like k, but continues to scroll beyond the beginning of the
86 file.
87 ESC-) or RIGHTARROW
89 Scroll horizontally right N characters, default half the screen
90 width (see the -# option). If a number N is specified, it be‐
91 comes the default for future RIGHTARROW and LEFTARROW commands.
92 While the text is scrolled, it acts as though the -S option
93 (chop lines) were in effect.
94 ESC-( or LEFTARROW
96 Scroll horizontally left N characters, default half the screen
97 width (see the -# option). If a number N is specified, it be‐
98 comes the default for future RIGHTARROW and LEFTARROW commands.
99 ESC-} or ^RIGHTARROW
101 Scroll horizontally right to show the end of the longest dis‐
102 played line.
103 ESC-{ or ^LEFTARROW
105 Scroll horizontally left back to the first column.
106 r or ^R or ^L
108 Repaint the screen.
109 R Repaint the screen, discarding any buffered input. That is,
111 reload the current file. Useful if the file is changing while
112 it is being viewed.
113 F Scroll forward, and keep trying to read when the end of file is
115 reached. Normally this command would be used when already at
116 the end of the file. It is a way to monitor the tail of a file
117 which is growing while it is being viewed. (The behavior is
118 similar to the "tail -f" command.) To stop waiting for more
119 data, enter the interrupt character (usually ^C). On some sys‐
120 tems you can also use ^X.
121 ESC-F Like F, but as soon as a line is found which matches the last
123 search pattern, the terminal bell is rung and forward scrolling
124 stops.
125 g or < or ESC-<
127 Go to line N in the file, default 1 (beginning of file). (Warn‐
128 ing: this may be slow if N is large.)
129 G or > or ESC->
131 Go to line N in the file, default the end of the file. (Warn‐
132 ing: this may be slow if N is large, or if N is not specified
133 and standard input, rather than a file, is being read.)
134 ESC-G Same as G, except if no number N is specified and the input is
136 standard input, goes to the last line which is currently
137 buffered.
138 p or % Go to a position N percent into the file. N should be between 0
140 and 100, and may contain a decimal point.
141 P Go to the line containing byte offset N in the file.
143 { If a left curly bracket appears in the top line displayed on the
145 screen, the { command will go to the matching right curly
146 bracket. The matching right curly bracket is positioned on the
147 bottom line of the screen. If there is more than one left curly
148 bracket on the top line, a number N may be used to specify the
149 N-th bracket on the line.
150 } If a right curly bracket appears in the bottom line displayed on
152 the screen, the } command will go to the matching left curly
153 bracket. The matching left curly bracket is positioned on the
154 top line of the screen. If there is more than one right curly
155 bracket on the top line, a number N may be used to specify the
156 N-th bracket on the line.
157 ( Like {, but applies to parentheses rather than curly brackets.
159 ) Like }, but applies to parentheses rather than curly brackets.
161 [ Like {, but applies to square brackets rather than curly brack‐
163 ets.
164 ] Like }, but applies to square brackets rather than curly brack‐
166 ets.
167 ESC-^F Followed by two characters, acts like {, but uses the two char‐
169 acters as open and close brackets, respectively. For example,
170 "ESC ^F < >" could be used to go forward to the > which matches
171 the < in the top displayed line.
172 ESC-^B Followed by two characters, acts like }, but uses the two char‐
174 acters as open and close brackets, respectively. For example,
175 "ESC ^B < >" could be used to go backward to the < which matches
176 the > in the bottom displayed line.
177 m Followed by any lowercase or uppercase letter, marks the first
179 displayed line with that letter. If the status column is en‐
180 abled via the -J option, the status column shows the marked
181 line.
182 M Acts like m, except the last displayed line is marked rather
184 than the first displayed line.
185 ' (Single quote.) Followed by any lowercase or uppercase letter,
187 returns to the position which was previously marked with that
188 letter. Followed by another single quote, returns to the posi‐
189 tion at which the last "large" movement command was executed.
190 Followed by a ^ or $, jumps to the beginning or end of the file
191 respectively. Marks are preserved when a new file is examined,
192 so the ' command can be used to switch between input files.
193 ^X^X Same as single quote.
195 ESC-m Followed by any lowercase or uppercase letter, clears the mark
197 identified by that letter.
198 /pattern
200 Search forward in the file for the N-th line containing the pat‐
201 tern. N defaults to 1. The pattern is a regular expression, as
202 recognized by the regular expression library supplied by your
203 system. The search starts at the first line displayed (but see
204 the -a and -j options, which change this).
205 Certain characters are special if entered at the beginning of
207 the pattern; they modify the type of search rather than become
208 part of the pattern:
209 ^N or !
211 Search for lines which do NOT match the pattern.
212 ^E or *
214 Search multiple files. That is, if the search reaches
215 the END of the current file without finding a match, the
216 search continues in the next file in the command line
217 list.
218 ^F or @
220 Begin the search at the first line of the FIRST file in
221 the command line list, regardless of what is currently
222 displayed on the screen or the settings of the -a or -j
223 options.
224 ^K Highlight any text which matches the pattern on the cur‐
226 rent screen, but don't move to the first match (KEEP cur‐
227 rent position).
228 ^R Don't interpret regular expression metacharacters; that
230 is, do a simple textual comparison.
231 ^W WRAP around the current file. That is, if the search
233 reaches the end of the current file without finding a
234 match, the search continues from the first line of the
235 current file up to the line where it started.
236 ?pattern
238 Search backward in the file for the N-th line containing the
239 pattern. The search starts at the last line displayed (but see
240 the -a and -j options, which change this).
241 Certain characters are special as in the / command:
243 ^N or !
245 Search for lines which do NOT match the pattern.
246 ^E or *
248 Search multiple files. That is, if the search reaches
249 the beginning of the current file without finding a
250 match, the search continues in the previous file in the
251 command line list.
252 ^F or @
254 Begin the search at the last line of the last file in the
255 command line list, regardless of what is currently dis‐
256 played on the screen or the settings of the -a or -j op‐
257 tions.
258 ^K As in forward searches.
260 ^R As in forward searches.
262 ^W WRAP around the current file. That is, if the search
264 reaches the beginning of the current file without finding
265 a match, the search continues from the last line of the
266 current file up to the line where it started.
267 ESC-/pattern
269 Same as "/*".
270 ESC-?pattern
272 Same as "?*".
273 n Repeat previous search, for N-th line containing the last pat‐
275 tern. If the previous search was modified by ^N, the search is
276 made for the N-th line NOT containing the pattern. If the pre‐
277 vious search was modified by ^E, the search continues in the
278 next (or previous) file if not satisfied in the current file.
279 If the previous search was modified by ^R, the search is done
280 without using regular expressions. There is no effect if the
281 previous search was modified by ^F or ^K.
282 N Repeat previous search, but in the reverse direction.
284 ESC-n Repeat previous search, but crossing file boundaries. The ef‐
286 fect is as if the previous search were modified by *.
287 ESC-N Repeat previous search, but in the reverse direction and cross‐
289 ing file boundaries.
290 ESC-u Undo search highlighting. Turn off highlighting of strings
292 matching the current search pattern. If highlighting is already
293 off because of a previous ESC-u command, turn highlighting back
294 on. Any search command will also turn highlighting back on.
295 (Highlighting can also be disabled by toggling the -G option; in
296 that case search commands do not turn highlighting back on.)
297 ESC-U Like ESC-u but also clears the saved search pattern. If the
299 status column is enabled via the -J option, this clears all
300 search matches marked in the status column.
301 &pattern
303 Display only lines which match the pattern; lines which do not
304 match the pattern are not displayed. If pattern is empty (if
305 you type & immediately followed by ENTER), any filtering is
306 turned off, and all lines are displayed. While filtering is in
307 effect, an ampersand is displayed at the beginning of the
308 prompt, as a reminder that some lines in the file may be hidden.
309 Multiple & commands may be entered, in which case only lines
310 which match all of the patterns will be displayed.
311 Certain characters are special as in the / command:
313 ^N or !
315 Display only lines which do NOT match the pattern.
316 ^R Don't interpret regular expression metacharacters; that
318 is, do a simple textual comparison.
319 :e [filename]
321 Examine a new file. If the filename is missing, the "current"
322 file (see the :n and :p commands below) from the list of files
323 in the command line is re-examined. A percent sign (%) in the
324 filename is replaced by the name of the current file. A pound
325 sign (#) is replaced by the name of the previously examined
326 file. However, two consecutive percent signs are simply re‐
327 placed with a single percent sign. This allows you to enter a
328 filename that contains a percent sign in the name. Similarly,
329 two consecutive pound signs are replaced with a single pound
330 sign. The filename is inserted into the command line list of
331 files so that it can be seen by subsequent :n and :p commands.
332 If the filename consists of several files, they are all inserted
333 into the list of files and the first one is examined. If the
334 filename contains one or more spaces, the entire filename should
335 be enclosed in double quotes (also see the -" option).
336 ^X^V or E
338 Same as :e. Warning: some systems use ^V as a special literal‐
339 ization character. On such systems, you may not be able to use
340 ^V.
341 :n Examine the next file (from the list of files given in the com‐
343 mand line). If a number N is specified, the N-th next file is
344 examined.
345 :p Examine the previous file in the command line list. If a number
347 N is specified, the N-th previous file is examined.
348 :x Examine the first file in the command line list. If a number N
350 is specified, the N-th file in the list is examined.
351 :d Remove the current file from the list of files.
353 t Go to the next tag, if there were more than one matches for the
355 current tag. See the -t option for more details about tags.
356 T Go to the previous tag, if there were more than one matches for
358 the current tag.
359 = or ^G or :f
361 Prints some information about the file being viewed, including
362 its name and the line number and byte offset of the bottom line
363 being displayed. If possible, it also prints the length of the
364 file, the number of lines in the file and the percent of the
365 file above the last displayed line.
366 - Followed by one of the command line option letters (see OPTIONS
368 below), this will change the setting of that option and print a
369 message describing the new setting. If a ^P (CONTROL-P) is en‐
370 tered immediately after the dash, the setting of the option is
371 changed but no message is printed. If the option letter has a
372 numeric value (such as -b or -h), or a string value (such as -P
373 or -t), a new value may be entered after the option letter. If
374 no new value is entered, a message describing the current set‐
375 ting is printed and nothing is changed.
376 -- Like the - command, but takes a long option name (see OPTIONS
378 below) rather than a single option letter. You must press ENTER
379 or RETURN after typing the option name. A ^P immediately after
380 the second dash suppresses printing of a message describing the
381 new setting, as in the - command.
382 -+ Followed by one of the command line option letters this will re‐
384 set the option to its default setting and print a message de‐
385 scribing the new setting. (The "-+X" command does the same
386 thing as "-+X" on the command line.) This does not work for
387 string-valued options.
388 --+ Like the -+ command, but takes a long option name rather than a
390 single option letter.
391 -! Followed by one of the command line option letters, this will
393 reset the option to the "opposite" of its default setting and
394 print a message describing the new setting. This does not work
395 for numeric or string-valued options.
396 --! Like the -! command, but takes a long option name rather than a
398 single option letter.
399 _ (Underscore.) Followed by one of the command line option let‐
401 ters, this will print a message describing the current setting
402 of that option. The setting of the option is not changed.
403 __ (Double underscore.) Like the _ (underscore) command, but takes
405 a long option name rather than a single option letter. You must
406 press ENTER or RETURN after typing the option name.
407 +cmd Causes the specified cmd to be executed each time a new file is
409 examined. For example, +G causes less to initially display each
410 file starting at the end rather than the beginning.
411 V Prints the version number of less being run.
413 q or Q or :q or :Q or ZZ
415 Exits less.
416 The following four commands may or may not be valid, depending on your
418 particular installation.
419 v Invokes an editor to edit the current file being viewed. The
421 editor is taken from the environment variable VISUAL if defined,
422 or EDITOR if VISUAL is not defined, or defaults to "vi" if nei‐
423 ther VISUAL nor EDITOR is defined. See also the discussion of
424 LESSEDIT under the section on PROMPTS below.
425 ! shell-command
427 Invokes a shell to run the shell-command given. A percent sign
428 (%) in the command is replaced by the name of the current file.
429 A pound sign (#) is replaced by the name of the previously exam‐
430 ined file. "!!" repeats the last shell command. "!" with no
431 shell command simply invokes a shell. On Unix systems, the
432 shell is taken from the environment variable SHELL, or defaults
433 to "sh". On MS-DOS and OS/2 systems, the shell is the normal
434 command processor.
435 | <m> shell-command
437 <m> represents any mark letter. Pipes a section of the input
438 file to the given shell command. The section of the file to be
439 piped is between the position marked by the letter and the cur‐
440 rent screen. The entire current screen is included, regardless
441 of whether the marked position is before or after the current
442 screen. <m> may also be ^ or $ to indicate beginning or end of
443 file respectively. If <m> is . or newline, the current screen
444 is piped.
445 s filename
447 Save the input to a file. This only works if the input is a
448 pipe, not an ordinary file.
449
451 Command line options are described below. Most options may be changed
452 while less is running, via the "-" command.
453 Most options may be given in one of two forms: either a dash followed
455 by a single letter, or two dashes followed by a long option name. A
456 long option name may be abbreviated as long as the abbreviation is un‐
457 ambiguous. For example, --quit-at-eof may be abbreviated --quit, but
458 not --qui, since both --quit-at-eof and --quiet begin with --qui. Some
459 long option names are in uppercase, such as --QUIT-AT-EOF, as distinct
460 from --quit-at-eof. Such option names need only have their first let‐
461 ter capitalized; the remainder of the name may be in either case. For
462 example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.
463 Options are also taken from the environment variable "LESS". For exam‐
465 ple, to avoid typing "less -options ..." each time less is invoked, you
466 might tell csh:
467 setenv LESS "-options"
469 or if you use sh:
471 LESS="-options"; export LESS
473 On MS-DOS, you don't need the quotes, but you should replace any per‐
475 cent signs in the options string by double percent signs.
476 The environment variable is parsed before the command line, so command
478 line options override the LESS environment variable. If an option ap‐
479 pears in the LESS variable, it can be reset to its default value on the
480 command line by beginning the command line option with "-+".
481 Some options like -k or -D require a string to follow the option let‐
483 ter. The string for that option is considered to end when a dollar
484 sign ($) is found. For example, you can set two -D options on MS-DOS
485 like this:
486 LESS="Dn9.1$Ds4.1"
488 If the --use-backslash option appears earlier in the options, then a
490 dollar sign or backslash may be included literally in an option string
491 by preceding it with a backslash. If the --use-backslash option is not
492 in effect, then backslashes are not treated specially, and there is no
493 way to include a dollar sign in the option string.
494 -? or --help
496 This option displays a summary of the commands accepted by less
497 (the same as the h command). (Depending on how your shell in‐
498 terprets the question mark, it may be necessary to quote the
499 question mark, thus: "-\?".)
500 -a or --search-skip-screen
502 By default, forward searches start at the top of the displayed
503 screen and backwards searches start at the bottom of the dis‐
504 played screen (except for repeated searches invoked by the n or
505 N commands, which start after or before the "target" line re‐
506 spectively; see the -j option for more about the target line).
507 The -a option causes forward searches to instead start at the
508 bottom of the screen and backward searches to start at the top
509 of the screen, thus skipping all lines displayed on the screen.
510 -A or --SEARCH-SKIP-SCREEN
512 Causes all forward searches (not just non-repeated searches) to
513 start just after the target line, and all backward searches to
514 start just before the target line. Thus, forward searches will
515 skip part of the displayed screen (from the first line up to and
516 including the target line). Similarly backwards searches will
517 skip the displayed screen from the last line up to and including
518 the target line. This was the default behavior in less versions
519 prior to 441.
520 -bn or --buffers=n
522 Specifies the amount of buffer space less will use for each
523 file, in units of kilobytes (1024 bytes). By default 64 KB of
524 buffer space is used for each file (unless the file is a pipe;
525 see the -B option). The -b option specifies instead that n
526 kilobytes of buffer space should be used for each file. If n is
527 -1, buffer space is unlimited; that is, the entire file can be
528 read into memory.
529 -B or --auto-buffers
531 By default, when data is read from a pipe, buffers are allocated
532 automatically as needed. If a large amount of data is read from
533 the pipe, this can cause a large amount of memory to be allo‐
534 cated. The -B option disables this automatic allocation of buf‐
535 fers for pipes, so that only 64 KB (or the amount of space spec‐
536 ified by the -b option) is used for the pipe. Warning: use of
537 -B can result in erroneous display, since only the most recently
538 viewed part of the piped data is kept in memory; any earlier
539 data is lost.
540 -c or --clear-screen
542 Causes full screen repaints to be painted from the top line
543 down. By default, full screen repaints are done by scrolling
544 from the bottom of the screen.
545 -C or --CLEAR-SCREEN
547 Same as -c, for compatibility with older versions of less.
548 -d or --dumb
550 The -d option suppresses the error message normally displayed if
551 the terminal is dumb; that is, lacks some important capability,
552 such as the ability to clear the screen or scroll backward. The
553 -d option does not otherwise change the behavior of less on a
554 dumb terminal.
555 -Dxcolor or --color=xcolor
557 Changes the color of different parts of the displayed text. x
558 is a single character which selects the type of text whose color
559 is being set:
560 B Binary characters.
562 C Control characters.
564 E Errors and informational messages.
566 M Mark letters in the status column.
568 N Line numbers enabled via the -N option.
570 P Prompts.
572 R The rscroll character.
574 S Search results.
576 W The highlight enabled via the -w option.
578 d Bold text.
580 k Blinking text.
582 s Standout text.
584 u Underlined text.
586 The uppercase letters can be used only when the --use-color op‐
588 tion is enabled. When text color is specified by both an upper‐
589 case letter and a lowercase letter, the uppercase letter takes
590 precedence. For example, error messages are normally displayed
591 as standout text. So if both "s" and "E" are given a color, the
592 "E" color applies to error messages, and the "s" color applies
593 to other standout text. The "d" and "u" letters refer to bold
594 and underline text formed by overstriking with backspaces (see
595 the -u option), not to text using ANSI escape sequences with the
596 -R option.
597 A lowercase letter may be followed by a + to indicate that both
599 the normal format change and the specified color should both be
600 used. For example, -Dug displays underlined text as green with‐
601 out underlining; the green color has replaced the usual under‐
602 line formatting. But -Du+g displays underlined text as both
603 green and in underlined format.
604 color is either a 4-bit color string or an 8-bit color string:
606 A 4-bit color string is zero, one or two characters, where the
608 first character specifies the foreground color and the second
609 specifies the background color as follows:
610 b Blue
612 c Cyan
614 g Green
616 k Black
618 m Magenta
620 r Red
622 w White
624 y Yellow
626 The corresponding upper-case letter denotes a brighter shade of
628 the color. For example, -DNGk displays line numbers as bright
629 green text on a black background, and -DEbR displays error mes‐
630 sages as blue text on a bright red background. If either char‐
631 acter is a "-" or is omitted, the corresponding color is set to
632 that of normal text.
633 An 8-bit color string is one or two decimal integers separated
635 by a dot, where the first integer specifies the foreground color
636 and the second specifies the background color. Each integer is
637 a value between 0 and 255 inclusive which selects a "CSI 38;5"
638 color value (see
639 https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_parameters)
640 If either integer is a "-" or is omitted, the corresponding col‐
641 or is set to that of normal text. On MS-DOS versions of less,
642 8-bit color is not supported; instead, decimal values are inter‐
643 preted as 4-bit CHAR_INFO.Attributes values (see
644 https://docs.microsoft.com/en-us/windows/console/char-info-str).
645 -e or --quit-at-eof
647 Causes less to automatically exit the second time it reaches
648 end-of-file. By default, the only way to exit less is via the
649 "q" command.
650 -E or --QUIT-AT-EOF
652 Causes less to automatically exit the first time it reaches end-
653 of-file.
654 -f or --force
656 Forces non-regular files to be opened. (A non-regular file is a
657 directory or a device special file.) Also suppresses the warn‐
658 ing message when a binary file is opened. By default, less will
659 refuse to open non-regular files. Note that some operating sys‐
660 tems will not allow directories to be read, even if -f is set.
661 -F or --quit-if-one-screen
663 Causes less to automatically exit if the entire file can be dis‐
664 played on the first screen.
665 -g or --hilite-search
667 Normally, less will highlight ALL strings which match the last
668 search command. The -g option changes this behavior to high‐
669 light only the particular string which was found by the last
670 search command. This can cause less to run somewhat faster than
671 the default.
672 -G or --HILITE-SEARCH
674 The -G option suppresses all highlighting of strings found by
675 search commands.
676 --old-bot
678 Reverts to the old bottom of screen behavior. This can be some‐
679 times desirable if the long lines are not wrapped correctly
680 when reaching the bottom of the terminal, while scrolling
681 forward.
682 -hn or --max-back-scroll=n
684 Specifies a maximum number of lines to scroll backward. If it
685 is necessary to scroll backward more than n lines, the screen is
686 repainted in a forward direction instead. (If the terminal does
687 not have the ability to scroll backward, -h0 is implied.)
688 -i or --ignore-case
690 Causes searches to ignore case; that is, uppercase and lowercase
691 are considered identical. This option is ignored if any upper‐
692 case letters appear in the search pattern; in other words, if a
693 pattern contains uppercase letters, then that search does not
694 ignore case.
695 -I or --IGNORE-CASE
697 Like -i, but searches ignore case even if the pattern contains
698 uppercase letters.
699 -jn or --jump-target=n
701 Specifies a line on the screen where the "target" line is to be
702 positioned. The target line is the line specified by any com‐
703 mand to search for a pattern, jump to a line number, jump to a
704 file percentage or jump to a tag. The screen line may be speci‐
705 fied by a number: the top line on the screen is 1, the next is
706 2, and so on. The number may be negative to specify a line rel‐
707 ative to the bottom of the screen: the bottom line on the screen
708 is -1, the second to the bottom is -2, and so on. Alternately,
709 the screen line may be specified as a fraction of the height of
710 the screen, starting with a decimal point: .5 is in the middle
711 of the screen, .3 is three tenths down from the first line, and
712 so on. If the line is specified as a fraction, the actual line
713 number is recalculated if the terminal window is resized, so
714 that the target line remains at the specified fraction of the
715 screen height. If any form of the -j option is used, repeated
716 forward searches (invoked with "n" or "N") begin at the line im‐
717 mediately after the target line, and repeated backward searches
718 begin at the target line, unless changed by -a or -A. For exam‐
719 ple, if "-j4" is used, the target line is the fourth line on the
720 screen, so forward searches begin at the fifth line on the
721 screen. However nonrepeated searches (invoked with "/" or "?")
722 always begin at the start or end of the current screen respec‐
723 tively.
724 -J or --status-column
726 Displays a status column at the left edge of the screen. The
727 status column shows the lines that matched the current search,
728 and any lines that are marked (via the m or M command).
729 -kfilename or --lesskey-file=filename
731 Causes less to open and interpret the named file as a lesskey(1)
732 binary file. Multiple -k options may be specified. If the
733 LESSKEY or LESSKEY_SYSTEM environment variable is set, or if a
734 lesskey file is found in a standard place (see KEY BINDINGS), it
735 is also used as a lesskey file.
736 --lesskey-src=filename
738 Causes less to open and interpret the named file as a lesskey(1)
739 source file. If the LESSKEYIN or LESSKEYIN_SYSTEM environment
740 variable is set, or if a lesskey source file is found in a stan‐
741 dard place (see KEY BINDINGS), it is also used as a lesskey
742 source file. Prior to version 582, the lesskey program needed
743 to be run to convert a lesskey source file to a lesskey binary
744 file for less to use. Newer versions of less read the lesskey
745 source file directly and ignore the binary file if the source
746 file exists.
747 -K or --quit-on-intr
749 Causes less to exit immediately (with status 2) when an inter‐
750 rupt character (usually ^C) is typed. Normally, an interrupt
751 character causes less to stop whatever it is doing and return to
752 its command prompt. Note that use of this option makes it im‐
753 possible to return to the command prompt from the "F" command.
754 -L or --no-lessopen
756 Ignore the LESSOPEN environment variable (see the INPUT PRE‐
757 PROCESSOR section below). This option can be set from within
758 less, but it will apply only to files opened subsequently, not
759 to the file which is currently open.
760 -m or --long-prompt
762 Causes less to prompt verbosely (like more), with the percent
763 into the file. By default, less prompts with a colon.
764 -M or --LONG-PROMPT
766 Causes less to prompt even more verbosely than more.
767 -n or --line-numbers
769 Suppresses line numbers. The default (to use line numbers) may
770 cause less to run more slowly in some cases, especially with a
771 very large input file. Suppressing line numbers with the -n op‐
772 tion will avoid this problem. Using line numbers means: the
773 line number will be displayed in the verbose prompt and in the =
774 command, and the v command will pass the current line number to
775 the editor (see also the discussion of LESSEDIT in PROMPTS be‐
776 low).
777 -N or --LINE-NUMBERS
779 Causes a line number to be displayed at the beginning of each
780 line in the display.
781 -ofilename or --log-file=filename
783 Causes less to copy its input to the named file as it is being
784 viewed. This applies only when the input file is a pipe, not an
785 ordinary file. If the file already exists, less will ask for
786 confirmation before overwriting it.
787 -Ofilename or --LOG-FILE=filename
789 The -O option is like -o, but it will overwrite an existing file
790 without asking for confirmation.
791 If no log file has been specified, the -o and -O options can be
793 used from within less to specify a log file. Without a file
794 name, they will simply report the name of the log file. The "s"
795 command is equivalent to specifying -o from within less.
796 -ppattern or --pattern=pattern
798 The -p option on the command line is equivalent to specifying
799 +/pattern; that is, it tells less to start at the first occur‐
800 rence of pattern in the file.
801 -Pprompt or --prompt=prompt
803 Provides a way to tailor the three prompt styles to your own
804 preference. This option would normally be put in the LESS envi‐
805 ronment variable, rather than being typed in with each less com‐
806 mand. Such an option must either be the last option in the LESS
807 variable, or be terminated by a dollar sign.
808 -Ps followed by a string changes the default (short) prompt to
809 that string.
810 -Pm changes the medium (-m) prompt.
811 -PM changes the long (-M) prompt.
812 -Ph changes the prompt for the help screen.
813 -P= changes the message printed by the = command.
814 -Pw changes the message printed while waiting for data (in the
815 F command).
816 All prompt strings consist of a sequence of letters and special
818 escape sequences. See the section on PROMPTS for more details.
819 -q or --quiet or --silent
821 Causes moderately "quiet" operation: the terminal bell is not
822 rung if an attempt is made to scroll past the end of the file or
823 before the beginning of the file. If the terminal has a "visual
824 bell", it is used instead. The bell will be rung on certain
825 other errors, such as typing an invalid character. The default
826 is to ring the terminal bell in all such cases.
827 -Q or --QUIET or --SILENT
829 Causes totally "quiet" operation: the terminal bell is never
830 rung. If the terminal has a "visual bell", it is used in all
831 cases where the terminal bell would have been rung.
832 -r or --raw-control-chars
834 Causes "raw" control characters to be displayed. The default is
835 to display control characters using the caret notation; for ex‐
836 ample, a control-A (octal 001) is displayed as "^A". Warning:
837 when the -r option is used, less cannot keep track of the actual
838 appearance of the screen (since this depends on how the screen
839 responds to each type of control character). Thus, various dis‐
840 play problems may result, such as long lines being split in the
841 wrong place.
842 USE OF THE -r OPTION IS NOT RECOMMENDED.
844 -R or --RAW-CONTROL-CHARS
846 Like -r, but only ANSI "color" escape sequences and OSC 8 hyper‐
847 link sequences are output in "raw" form. Unlike -r, the screen
848 appearance is maintained correctly, provided that there are no
849 escape sequences in the file other than these types of escape
850 sequences. Color escape sequences are only supported when the
851 color is changed within one line, not across lines. In other
852 words, the beginning of each line is assumed to be normal (non-
853 colored), regardless of any escape sequences in previous lines.
854 For the purpose of keeping track of screen appearance, these es‐
855 cape sequences are assumed to not move the cursor.
856 OSC 8 hyperlinks are sequences of the form:
858 ESC ] 8 ; ... \7
860 The terminating sequence may be either a BEL character (\7) or
862 the two-character sequence "ESC \".
863 ANSI color escape sequences are sequences of the form:
865 ESC [ ... m
867 where the "..." is zero or more color specification characters.
869 You can make less think that characters other than "m" can end
870 ANSI color escape sequences by setting the environment variable
871 LESSANSIENDCHARS to the list of characters which can end a color
872 escape sequence. And you can make less think that characters
873 other than the standard ones may appear between the ESC and the
874 m by setting the environment variable LESSANSIMIDCHARS to the
875 list of characters which can appear.
876 -s or --squeeze-blank-lines
878 Causes consecutive blank lines to be squeezed into a single
879 blank line. This is useful when viewing nroff output.
880 -S or --chop-long-lines
882 Causes lines longer than the screen width to be chopped (trun‐
883 cated) rather than wrapped. That is, the portion of a long line
884 that does not fit in the screen width is not displayed until you
885 press RIGHT-ARROW. The default is to wrap long lines; that is,
886 display the remainder on the next line.
887 -ttag or --tag=tag
889 The -t option, followed immediately by a TAG, will edit the file
890 containing that tag. For this to work, tag information must be
891 available; for example, there may be a file in the current di‐
892 rectory called "tags", which was previously built by ctags(1) or
893 an equivalent command. If the environment variable LESSGLOBALT‐
894 AGS is set, it is taken to be the name of a command compatible
895 with global(1), and that command is executed to find the tag.
896 (See http://www.gnu.org/software/global/global.html). The -t
897 option may also be specified from within less (using the - com‐
898 mand) as a way of examining a new file. The command ":t" is
899 equivalent to specifying -t from within less.
900 -Ttagsfile or --tag-file=tagsfile
902 Specifies a tags file to be used instead of "tags".
903 -u or --underline-special
905 Causes backspaces and carriage returns to be treated as print‐
906 able characters; that is, they are sent to the terminal when
907 they appear in the input.
908 -U or --UNDERLINE-SPECIAL
910 Causes backspaces, tabs, carriage returns and "formatting char‐
911 acters" (as defined by Unicode) to be treated as control charac‐
912 ters; that is, they are handled as specified by the -r option.
913 By default, if neither -u nor -U is given, backspaces which ap‐
915 pear adjacent to an underscore character are treated specially:
916 the underlined text is displayed using the terminal's hardware
917 underlining capability. Also, backspaces which appear between
918 two identical characters are treated specially: the overstruck
919 text is printed using the terminal's hardware boldface capabili‐
920 ty. Other backspaces are deleted, along with the preceding
921 character. Carriage returns immediately followed by a newline
922 are deleted. Other carriage returns are handled as specified by
923 the -r option. Unicode formatting characters, such as the Byte
924 Order Mark, are sent to the terminal. Text which is overstruck
925 or underlined can be searched for if neither -u nor -U is in ef‐
926 fect.
927 -V or --version
929 Displays the version number of less.
930 -w or --hilite-unread
932 Temporarily highlights the first "new" line after a forward
933 movement of a full page. The first "new" line is the line imme‐
934 diately following the line previously at the bottom of the
935 screen. Also highlights the target line after a g or p command.
936 The highlight is removed at the next command which causes move‐
937 ment. The entire line is highlighted, unless the -J option is
938 in effect, in which case only the status column is highlighted.
939 -W or --HILITE-UNREAD
941 Like -w, but temporarily highlights the first new line after any
942 forward movement command larger than one line.
943 -xn,... or --tabs=n,...
945 Sets tab stops. If only one n is specified, tab stops are set
946 at multiples of n. If multiple values separated by commas are
947 specified, tab stops are set at those positions, and then con‐
948 tinue with the same spacing as the last two. For example,
949 -x9,17 will set tabs at positions 9, 17, 25, 33, etc. The de‐
950 fault for n is 8.
951 -X or --no-init
953 Disables sending the termcap initialization and deinitialization
954 strings to the terminal. This is sometimes desirable if the
955 deinitialization string does something unnecessary, like clear‐
956 ing the screen.
957 -yn or --max-forw-scroll=n
959 Specifies a maximum number of lines to scroll forward. If it is
960 necessary to scroll forward more than n lines, the screen is re‐
961 painted instead. The -c or -C option may be used to repaint
962 from the top of the screen if desired. By default, any forward
963 movement causes scrolling.
964 -zn or --window=n or -n
966 Changes the default scrolling window size to n lines. The de‐
967 fault is one screenful. The z and w commands can also be used
968 to change the window size. The "z" may be omitted for compati‐
969 bility with some versions of more. If the number n is negative,
970 it indicates n lines less than the current screen size. For ex‐
971 ample, if the screen is 24 lines, -z-4 sets the scrolling window
972 to 20 lines. If the screen is resized to 40 lines, the
973 scrolling window automatically changes to 36 lines.
974 -"cc or --quotes=cc
976 Changes the filename quoting character. This may be necessary
977 if you are trying to name a file which contains both spaces and
978 quote characters. Followed by a single character, this changes
979 the quote character to that character. Filenames containing a
980 space should then be surrounded by that character rather than by
981 double quotes. Followed by two characters, changes the open
982 quote to the first character, and the close quote to the second
983 character. Filenames containing a space should then be preceded
984 by the open quote character and followed by the close quote
985 character. Note that even after the quote characters are
986 changed, this option remains -" (a dash followed by a double
987 quote).
988 -~ or --tilde
990 Normally lines after end of file are displayed as a single tilde
991 (~). This option causes lines after end of file to be displayed
992 as blank lines.
993 -# or --shift
995 Specifies the default number of positions to scroll horizontally
996 in the RIGHTARROW and LEFTARROW commands. If the number speci‐
997 fied is zero, it sets the default number of positions to one
998 half of the screen width. Alternately, the number may be speci‐
999 fied as a fraction of the width of the screen, starting with a
1000 decimal point: .5 is half of the screen width, .3 is three
1001 tenths of the screen width, and so on. If the number is speci‐
1002 fied as a fraction, the actual number of scroll positions is re‐
1003 calculated if the terminal window is resized, so that the actual
1004 scroll remains at the specified fraction of the screen width.
1005 --file-size
1007 If --file-size is specified, less will determine the size of the
1008 file immediately after opening the file. Normally this is not
1009 done, because it can be slow if the input file is large.
1010 --follow-name
1012 Normally, if the input file is renamed while an F command is ex‐
1013 ecuting, less will continue to display the contents of the orig‐
1014 inal file despite its name change. If --follow-name is speci‐
1015 fied, during an F command less will periodically attempt to re‐
1016 open the file by name. If the reopen succeeds and the file is a
1017 different file from the original (which means that a new file
1018 has been created with the same name as the original (now re‐
1019 named) file), less will display the contents of that new file.
1020 --incsearch
1022 Subsequent search commands will be "incremental"; that is, less
1023 will advance to the next line containing the search pattern as
1024 each character of the pattern is typed in.
1025 --line-num-width
1027 Sets the minimum width of the line number field when the -N op‐
1028 tion is in effect. The default is 7 characters.
1029 --mouse
1031 Enables mouse input: scrolling the mouse wheel down moves for‐
1032 ward in the file, scrolling the mouse wheel up moves backwards
1033 in the file, and clicking the mouse sets the "#" mark to the
1034 line where the mouse is clicked. The number of lines to scroll
1035 when the wheel is moved can be set by the --wheel-lines option.
1036 Mouse input works only on terminals which support X11 mouse re‐
1037 porting, and on the Windows version of less.
1038 --MOUSE
1040 Like --mouse, except the direction scrolled on mouse wheel move‐
1041 ment is reversed.
1042 --no-keypad
1044 Disables sending the keypad initialization and deinitialization
1045 strings to the terminal. This is sometimes useful if the keypad
1046 strings make the numeric keypad behave in an undesirable manner.
1047 --no-histdups
1049 This option changes the behavior so that if a search string or
1050 file name is typed in, and the same string is already in the
1051 history list, the existing copy is removed from the history list
1052 before the new one is added. Thus, a given string will appear
1053 only once in the history list. Normally, a string may appear
1054 multiple times.
1055 --rscroll
1057 This option changes the character used to mark truncated lines.
1058 It may begin with a two-character attribute indicator like LESS‐
1059 BINFMT does. If there is no attribute indicator, standout is
1060 used. If set to "-", truncated lines are not marked.
1061 --save-marks
1063 Save marks in the history file, so marks are retained across
1064 different invocations of less.
1065 --status-col-width
1067 Sets the width of the status column when the -J option is in ef‐
1068 fect. The default is 2 characters.
1069 --use-backslash
1071 This option changes the interpretations of options which follow
1072 this one. After the --use-backslash option, any backslash in an
1073 option string is removed and the following character is taken
1074 literally. This allows a dollar sign to be included in option
1075 strings.
1076 --use-color
1078 Enables the colored text in various places. The -D option can
1079 be used to change the colors. Colored text works only if the
1080 terminal supports ANSI color escape sequences (as defined in EC‐
1081 MA-48 SGR; see
1082 https://www.ecma-international.org/publications-and-
1083 standards/standards/ecma-48).
1084 --wheel-lines=n
1086 Set the number of lines to scroll when the mouse wheel is
1087 scrolled and the --mouse or --MOUSE option is in effect. The
1088 default is 1 line.
1089 -- A command line argument of "--" marks the end of option argu‐
1091 ments. Any arguments following this are interpreted as file‐
1092 names. This can be useful when viewing a file whose name begins
1093 with a "-" or "+".
1094 + If a command line option begins with +, the remainder of that
1096 option is taken to be an initial command to less. For example,
1097 +G tells less to start at the end of the file rather than the
1098 beginning, and +/xyz tells it to start at the first occurrence
1099 of "xyz" in the file. As a special case, +<number> acts like
1100 +<number>g; that is, it starts the display at the specified line
1101 number (however, see the caveat under the "g" command above).
1102 If the option starts with ++, the initial command applies to ev‐
1103 ery file being viewed, not just the first one. The + command
1104 described previously may also be used to set (or change) an ini‐
1105 tial command for every file.
1106
1108 When entering a command line at the bottom of the screen (for example,
1109 a filename for the :e command, or the pattern for a search command),
1110 certain keys can be used to manipulate the command line. Most commands
1111 have an alternate form in [ brackets ] which can be used if a key does
1112 not exist on a particular keyboard. (Note that the forms beginning
1113 with ESC do not work in some MS-DOS and Windows systems because ESC is
1114 the line erase character.) Any of these special keys may be entered
1115 literally by preceding it with the "literal" character, either ^V or
1116 ^A. A backslash itself may also be entered literally by entering two
1117 backslashes.
1118 LEFTARROW [ ESC-h ]
1120 Move the cursor one space to the left.
1121 RIGHTARROW [ ESC-l ]
1123 Move the cursor one space to the right.
1124 ^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
1126 (That is, CONTROL and LEFTARROW simultaneously.) Move the cur‐
1127 sor one word to the left.
1128 ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
1130 (That is, CONTROL and RIGHTARROW simultaneously.) Move the cur‐
1131 sor one word to the right.
1132 HOME [ ESC-0 ]
1134 Move the cursor to the beginning of the line.
1135 END [ ESC-$ ]
1137 Move the cursor to the end of the line.
1138 BACKSPACE
1140 Delete the character to the left of the cursor, or cancel the
1141 command if the command line is empty.
1142 DELETE or [ ESC-x ]
1144 Delete the character under the cursor.
1145 ^BACKSPACE [ ESC-BACKSPACE ]
1147 (That is, CONTROL and BACKSPACE simultaneously.) Delete the
1148 word to the left of the cursor.
1149 ^DELETE [ ESC-X or ESC-DELETE ]
1151 (That is, CONTROL and DELETE simultaneously.) Delete the word
1152 under the cursor.
1153 UPARROW [ ESC-k ]
1155 Retrieve the previous command line. If you first enter some
1156 text and then press UPARROW, it will retrieve the previous com‐
1157 mand which begins with that text.
1158 DOWNARROW [ ESC-j ]
1160 Retrieve the next command line. If you first enter some text
1161 and then press DOWNARROW, it will retrieve the next command
1162 which begins with that text.
1163 TAB Complete the partial filename to the left of the cursor. If it
1165 matches more than one filename, the first match is entered into
1166 the command line. Repeated TABs will cycle thru the other
1167 matching filenames. If the completed filename is a directory, a
1168 "/" is appended to the filename. (On MS-DOS systems, a "\" is
1169 appended.) The environment variable LESSSEPARATOR can be used
1170 to specify a different character to append to a directory name.
1171 BACKTAB [ ESC-TAB ]
1173 Like, TAB, but cycles in the reverse direction thru the matching
1174 filenames.
1175 ^L Complete the partial filename to the left of the cursor. If it
1177 matches more than one filename, all matches are entered into the
1178 command line (if they fit).
1179 ^U (Unix and OS/2) or ESC (MS-DOS)
1181 Delete the entire command line, or cancel the command if the
1182 command line is empty. If you have changed your line-kill char‐
1183 acter in Unix to something other than ^U, that character is used
1184 instead of ^U.
1185 ^G Delete the entire command line and return to the main prompt.
1187
1189 You may define your own less commands by creating a lesskey source
1190 file. This file specifies a set of command keys and an action associ‐
1191 ated with each key. You may also change the line-editing keys (see
1192 LINE EDITING), and to set environment variables. If the environment
1193 variable LESSKEYIN is set, less uses that as the name of the lesskey
1194 source file. Otherwise, less looks in a standard place for the lesskey
1195 source file: On Unix systems, less looks for a lesskey file called
1196 "$XDG_CONFIG_HOME/lesskey" or "$HOME/.lesskey". On MS-DOS and Windows
1197 systems, less looks for a lesskey file called "$HOME/_lesskey", and if
1198 it is not found there, then looks for a lesskey file called "_lesskey"
1199 in any directory specified in the PATH environment variable. On OS/2
1200 systems, less looks for a lesskey file called "$HOME/lesskey.ini", and
1201 if it is not found, then looks for a lesskey file called "lesskey.ini"
1202 in any directory specified in the INIT environment variable, and if it
1203 not found there, then looks for a lesskey file called "lesskey.ini" in
1204 any directory specified in the PATH environment variable. See the
1205 lesskey manual page for more details.
1206 A system-wide lesskey source file may also be set up to provide key
1208 bindings. If a key is defined in both a local lesskey file and in the
1209 system-wide file, key bindings in the local file take precedence over
1210 those in the system-wide file. If the environment variable
1211 LESSKEYIN_SYSTEM is set, less uses that as the name of the system-wide
1212 lesskey file. Otherwise, less looks in a standard place for the sys‐
1213 tem-wide lesskey file: On Unix systems, the system-wide lesskey file is
1214 /usr/local/etc/syslesskey. (However, if less was built with a differ‐
1215 ent sysconf directory than /usr/local/etc, that directory is where the
1216 sysless file is found.) On MS-DOS and Windows systems, the system-wide
1217 lesskey file is c:\_syslesskey. On OS/2 systems, the system-wide
1218 lesskey file is c:\syslesskey.ini.
1219 Previous versions of less (before v582) used lesskey files with a bina‐
1221 ry format, produced by the lesskey program. It is no longer necessary
1222 to use the lesskey program.
1223
1225 You may define an "input preprocessor" for less. Before less opens a
1226 file, it first gives your input preprocessor a chance to modify the way
1227 the contents of the file are displayed. An input preprocessor is sim‐
1228 ply an executable program (or shell script), which writes the contents
1229 of the file to a different file, called the replacement file. The con‐
1230 tents of the replacement file are then displayed in place of the con‐
1231 tents of the original file. However, it will appear to the user as if
1232 the original file is opened; that is, less will display the original
1233 filename as the name of the current file.
1234 An input preprocessor receives one command line argument, the original
1236 filename, as entered by the user. It should create the replacement
1237 file, and when finished, print the name of the replacement file to its
1238 standard output. If the input preprocessor does not output a replace‐
1239 ment filename, less uses the original file, as normal. The input pre‐
1240 processor is not called when viewing standard input. To set up an in‐
1241 put preprocessor, set the LESSOPEN environment variable to a command
1242 line which will invoke your input preprocessor. This command line
1243 should include one occurrence of the string "%s", which will be re‐
1244 placed by the filename when the input preprocessor command is invoked.
1245 When less closes a file opened in such a way, it will call another pro‐
1247 gram, called the input postprocessor, which may perform any desired
1248 clean-up action (such as deleting the replacement file created by
1249 LESSOPEN). This program receives two command line arguments, the orig‐
1250 inal filename as entered by the user, and the name of the replacement
1251 file. To set up an input postprocessor, set the LESSCLOSE environment
1252 variable to a command line which will invoke your input postprocessor.
1253 It may include two occurrences of the string "%s"; the first is re‐
1254 placed with the original name of the file and the second with the name
1255 of the replacement file, which was output by LESSOPEN.
1256 For example, on many Unix systems, these two scripts will allow you to
1258 keep files in compressed format, but still let less view them directly:
1259 lessopen.sh:
1261 #! /bin/sh
1262 case "$1" in
1263 *.Z) TEMPFILE=$(mktemp)
1264 uncompress -c $1 >$TEMPFILE 2>/dev/null
1265 if [ -s $TEMPFILE ]; then
1266 echo $TEMPFILE
1267 else
1268 rm -f $TEMPFILE
1269 fi
1270 ;;
1271 esac
1272 lessclose.sh:
1274 #! /bin/sh
1275 rm $2
1276 To use these scripts, put them both where they can be executed and set
1278 LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s". More
1279 complex LESSOPEN and LESSCLOSE scripts may be written to accept other
1280 types of compressed files, and so on.
1281 It is also possible to set up an input preprocessor to pipe the file
1283 data directly to less, rather than putting the data into a replacement
1284 file. This avoids the need to decompress the entire file before start‐
1285 ing to view it. An input preprocessor that works this way is called an
1286 input pipe. An input pipe, instead of writing the name of a replace‐
1287 ment file on its standard output, writes the entire contents of the re‐
1288 placement file on its standard output. If the input pipe does not
1289 write any characters on its standard output, then there is no replace‐
1290 ment file and less uses the original file, as normal. To use an input
1291 pipe, make the first character in the LESSOPEN environment variable a
1292 vertical bar (|) to signify that the input preprocessor is an input
1293 pipe. As with non-pipe input preprocessors, the command string must
1294 contain one occurrence of %s, which is replaced with the filename of
1295 the input file.
1296 For example, on many Unix systems, this script will work like the pre‐
1298 vious example scripts:
1299 lesspipe.sh:
1301 #! /bin/sh
1302 case "$1" in
1303 *.Z) uncompress -c $1 2>/dev/null
1304 ;;
1305 *) exit 1
1306 ;;
1307 esac
1308 exit $?
1309 To use this script, put it where it can be executed and set
1311 LESSOPEN="|lesspipe.sh %s".
1312 Note that a preprocessor cannot output an empty file, since that is in‐
1314 terpreted as meaning there is no replacement, and the original file is
1315 used. To avoid this, if LESSOPEN starts with two vertical bars, the
1316 exit status of the script becomes meaningful. If the exit status is
1317 zero, the output is considered to be replacement text, even if it is
1318 empty. If the exit status is nonzero, any output is ignored and the
1319 original file is used. For compatibility with previous versions of
1320 less, if LESSOPEN starts with only one vertical bar, the exit status of
1321 the preprocessor is ignored.
1322 When an input pipe is used, a LESSCLOSE postprocessor can be used, but
1324 it is usually not necessary since there is no replacement file to clean
1325 up. In this case, the replacement file name passed to the LESSCLOSE
1326 postprocessor is "-".
1327 For compatibility with previous versions of less, the input preproces‐
1329 sor or pipe is not used if less is viewing standard input. However, if
1330 the first character of LESSOPEN is a dash (-), the input preprocessor
1331 is used on standard input as well as other files. In this case, the
1332 dash is not considered to be part of the preprocessor command. If
1333 standard input is being viewed, the input preprocessor is passed a file
1334 name consisting of a single dash. Similarly, if the first two charac‐
1335 ters of LESSOPEN are vertical bar and dash (|-) or two vertical bars
1336 and a dash (||-), the input pipe is used on standard input as well as
1337 other files. Again, in this case the dash is not considered to be part
1338 of the input pipe command.
1339 There are used following files to set up default preprocessor:
1341 /etc/profile.d/less.sh
1342 /etc/profile.d/less.csh
1343 These files set up /usr/bin/lesspipe.sh as a default filter. An user
1344 defined filter can be specified in ~/.lessfilter. This file should have
1345 an execute bit set and accept only one parameter, which represents a
1346 filename. If the user defined filter process the file, zero should be
1347 returned. Otherwise ~/.lessfilter tries to handle the file.
1348
1351 There are three types of characters in the input file:
1352 normal characters
1354 can be displayed directly to the screen.
1355 control characters
1357 should not be displayed directly, but are expected to be found
1358 in ordinary text files (such as backspace and tab).
1359 binary characters
1361 should not be displayed directly and are not expected to be
1362 found in text files.
1363 A "character set" is simply a description of which characters are to be
1365 considered normal, control, and binary. The LESSCHARSET environment
1366 variable may be used to select a character set. Possible values for
1367 LESSCHARSET are:
1368 ascii BS, TAB, NL, CR, and formfeed are control characters, all chars
1370 with values between 32 and 126 are normal, and all others are
1371 binary.
1372 iso8859
1374 Selects an ISO 8859 character set. This is the same as ASCII,
1375 except characters between 160 and 255 are treated as normal
1376 characters.
1377 latin1 Same as iso8859.
1379 latin9 Same as iso8859.
1381 dos Selects a character set appropriate for MS-DOS.
1383 ebcdic Selects an EBCDIC character set.
1385 IBM-1047
1387 Selects an EBCDIC character set used by OS/390 Unix Services.
1388 This is the EBCDIC analogue of latin1. You get similar results
1389 by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
1390 environment.
1391 koi8-r Selects a Russian character set.
1393 next Selects a character set appropriate for NeXT computers.
1395 utf-8 Selects the UTF-8 encoding of the ISO 10646 character set.
1397 UTF-8 is special in that it supports multi-byte characters in
1398 the input file. It is the only character set that supports mul‐
1399 ti-byte characters.
1400 windows
1402 Selects a character set appropriate for Microsoft Windows (cp
1403 1251).
1404 In rare cases, it may be desired to tailor less to use a character set
1406 other than the ones definable by LESSCHARSET. In this case, the envi‐
1407 ronment variable LESSCHARDEF can be used to define a character set. It
1408 should be set to a string where each character in the string represents
1409 one character in the character set. The character "." is used for a
1410 normal character, "c" for control, and "b" for binary. A decimal num‐
1411 ber may be used for repetition. For example, "bccc4b." would mean
1412 character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are bina‐
1413 ry, and 8 is normal. All characters after the last are taken to be the
1414 same as the last, so characters 9 through 255 would be normal. (This
1415 is an example, and does not necessarily represent any real character
1416 set.)
1417 This table shows the value of LESSCHARDEF which is equivalent to each
1419 of the possible values for LESSCHARSET:
1420 ascii 8bcccbcc18b95.b
1422 dos 8bcccbcc12bc5b95.b.
1423 ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
1424 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
1425 IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
1426 191.b
1427 iso8859 8bcccbcc18b95.33b.
1428 koi8-r 8bcccbcc18b95.b128.
1429 latin1 8bcccbcc18b95.33b.
1430 next 8bcccbcc18b95.bb125.bb
1431 If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings
1433 "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_CTYPE or
1434 LANG environment variables, then the default character set is utf-8.
1435 If that string is not found, but your system supports the setlocale in‐
1437 terface, less will use setlocale to determine the character set. set‐
1438 locale is controlled by setting the LANG or LC_CTYPE environment vari‐
1439 ables.
1440 Finally, if the setlocale interface is also not available, the default
1442 character set is latin1.
1443 Control and binary characters are displayed in standout (reverse
1445 video). Each such character is displayed in caret notation if possible
1446 (e.g. ^A for control-A). Caret notation is used only if inverting the
1447 0100 bit results in a normal printable character. Otherwise, the char‐
1448 acter is displayed as a hex number in angle brackets. This format can
1449 be changed by setting the LESSBINFMT environment variable. LESSBINFMT
1450 may begin with a "*" and one character to select the display attribute:
1451 "*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout,
1452 and "*n" is normal. If LESSBINFMT does not begin with a "*", normal
1453 attribute is assumed. The remainder of LESSBINFMT is a string which
1454 may include one printf-style escape sequence (a % followed by x, X, o,
1455 d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters
1456 are displayed in underlined hexadecimal surrounded by brackets. The
1457 default if no LESSBINFMT is specified is "*s<%02X>". Warning: the re‐
1458 sult of expanding the character via LESSBINFMT must be less than 31
1459 characters.
1460 When the character set is utf-8, the LESSUTFBINFMT environment variable
1462 acts similarly to LESSBINFMT but it applies to Unicode code points that
1463 were successfully decoded but are unsuitable for display (e.g., unas‐
1464 signed code points). Its default value is "<U+%04lX>". Note that
1465 LESSUTFBINFMT and LESSBINFMT share their display attribute setting
1466 ("*x") so specifying one will affect both; LESSUTFBINFMT is read after
1467 LESSBINFMT so its setting, if any, will have priority. Problematic
1468 octets in a UTF-8 file (octets of a truncated sequence, octets of a
1469 complete but non-shortest form sequence, invalid octets, and stray
1470 trailing octets) are displayed individually using LESSBINFMT so as to
1471 facilitate diagnostic of how the UTF-8 file is ill-formed.
1472
1474 The -P option allows you to tailor the prompt to your preference. The
1475 string given to the -P option replaces the specified prompt string.
1476 Certain characters in the string are interpreted specially. The prompt
1477 mechanism is rather complicated to provide flexibility, but the ordi‐
1478 nary user need not understand the details of constructing personalized
1479 prompt strings.
1480 A percent sign followed by a single character is expanded according to
1482 what the following character is:
1483 %bX Replaced by the byte offset into the current input file. The b
1485 is followed by a single character (shown as X above) which spec‐
1486 ifies the line whose byte offset is to be used. If the charac‐
1487 ter is a "t", the byte offset of the top line in the display is
1488 used, an "m" means use the middle line, a "b" means use the bot‐
1489 tom line, a "B" means use the line just after the bottom line,
1490 and a "j" means use the "target" line, as specified by the -j
1491 option.
1492 %B Replaced by the size of the current input file.
1494 %c Replaced by the column number of the text appearing in the first
1496 column of the screen.
1497 %dX Replaced by the page number of a line in the input file. The
1499 line to be used is determined by the X, as with the %b option.
1500 %D Replaced by the number of pages in the input file, or equiva‐
1502 lently, the page number of the last line in the input file.
1503 %E Replaced by the name of the editor (from the VISUAL environment
1505 variable, or the EDITOR environment variable if VISUAL is not
1506 defined). See the discussion of the LESSEDIT feature below.
1507 %f Replaced by the name of the current input file.
1509 %F Replaced by the last component of the name of the current input
1511 file.
1512 %g Replaced by the shell-escaped name of the current input file.
1514 This is useful when the expanded string will be used in a shell
1515 command, such as in LESSEDIT.
1516 %i Replaced by the index of the current file in the list of input
1518 files.
1519 %lX Replaced by the line number of a line in the input file. The
1521 line to be used is determined by the X, as with the %b option.
1522 %L Replaced by the line number of the last line in the input file.
1524 %m Replaced by the total number of input files.
1526 %pX Replaced by the percent into the current input file, based on
1528 byte offsets. The line used is determined by the X as with the
1529 %b option.
1530 %PX Replaced by the percent into the current input file, based on
1532 line numbers. The line used is determined by the X as with the
1533 %b option.
1534 %s Same as %B.
1536 %t Causes any trailing spaces to be removed. Usually used at the
1538 end of the string, but may appear anywhere.
1539 %T Normally expands to the word "file". However if viewing files
1541 via a tags list using the -t option, it expands to the word
1542 "tag".
1543 %x Replaced by the name of the next input file in the list.
1545 If any item is unknown (for example, the file size if input is a pipe),
1547 a question mark is printed instead.
1548 The format of the prompt string can be changed depending on certain
1550 conditions. A question mark followed by a single character acts like
1551 an "IF": depending on the following character, a condition is evaluat‐
1552 ed. If the condition is true, any characters following the question
1553 mark and condition character, up to a period, are included in the
1554 prompt. If the condition is false, such characters are not included.
1555 A colon appearing between the question mark and the period can be used
1556 to establish an "ELSE": any characters between the colon and the period
1557 are included in the string if and only if the IF condition is false.
1558 Condition characters (which follow a question mark) may be:
1559 ?a True if any characters have been included in the prompt so far.
1561 ?bX True if the byte offset of the specified line is known.
1563 ?B True if the size of current input file is known.
1565 ?c True if the text is horizontally shifted (%c is not zero).
1567 ?dX True if the page number of the specified line is known.
1569 ?e True if at end-of-file.
1571 ?f True if there is an input filename (that is, if input is not a
1573 pipe).
1574 ?lX True if the line number of the specified line is known.
1576 ?L True if the line number of the last line in the file is known.
1578 ?m True if there is more than one input file.
1580 ?n True if this is the first prompt in a new input file.
1582 ?pX True if the percent into the current input file, based on byte
1584 offsets, of the specified line is known.
1585 ?PX True if the percent into the current input file, based on line
1587 numbers, of the specified line is known.
1588 ?s Same as "?B".
1590 ?x True if there is a next input file (that is, if the current in‐
1592 put file is not the last one).
1593 Any characters other than the special ones (question mark, colon, peri‐
1595 od, percent, and backslash) become literally part of the prompt. Any
1596 of the special characters may be included in the prompt literally by
1597 preceding it with a backslash.
1598 Some examples:
1600 ?f%f:Standard input.
1602 This prompt prints the filename, if known; otherwise the string "Stan‐
1604 dard input".
1605 ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
1607 This prompt would print the filename, if known. The filename is fol‐
1609 lowed by the line number, if known, otherwise the percent if known,
1610 otherwise the byte offset if known. Otherwise, a dash is printed. No‐
1611 tice how each question mark has a matching period, and how the % after
1612 the %pt is included literally by escaping it with a backslash.
1613 ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x..%t";
1615 This prints the filename if this is the first prompt in a file, fol‐
1617 lowed by the "file N of N" message if there is more than one input
1618 file. Then, if we are at end-of-file, the string "(END)" is printed
1619 followed by the name of the next file, if there is one. Finally, any
1620 trailing spaces are truncated. This is the default prompt. For refer‐
1621 ence, here are the defaults for the other two prompts (-m and -M re‐
1622 spectively). Each is broken into two lines here for readability only.
1623 ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x.:
1625 ?pB%pB\%:byte %bB?s/%s...%t
1626 ?f%f .?n?m(%T %i of %m) ..?ltlines %lt-%lb?L/%L. :
1628 byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
1629 And here is the default message produced by the = command:
1631 ?f%f .?m(%T %i of %m) .?ltlines %lt-%lb?L/%L. .
1633 byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
1634 The prompt expansion features are also used for another purpose: if an
1636 environment variable LESSEDIT is defined, it is used as the command to
1637 be executed when the v command is invoked. The LESSEDIT string is ex‐
1638 panded in the same way as the prompt strings. The default value for
1639 LESSEDIT is:
1640 %E ?lm+%lm. %g
1642 Note that this expands to the editor name, followed by a + and the line
1644 number, followed by the shell-escaped file name. If your editor does
1645 not accept the "+linenumber" syntax, or has other differences in invo‐
1646 cation syntax, the LESSEDIT variable can be changed to modify this de‐
1647 fault.
1648
1650 When the environment variable LESSSECURE is set to 1, less runs in a
1651 "secure" mode. This means these features are disabled:
1652 ! the shell command
1654 | the pipe command
1656 :e the examine command.
1658 v the editing command
1660 s -o log files
1662 -k use of lesskey files
1664 -t use of tags files
1666 metacharacters in filenames, such as *
1668 filename completion (TAB, ^L)
1670 Less can also be compiled to be permanently in "secure" mode.
1672
1674 If the environment variable LESS_IS_MORE is set to 1, or if the program
1675 is invoked via a file link named "more", less behaves (mostly) in con‐
1676 formance with the POSIX "more" command specification. In this mode,
1677 less behaves differently in these ways:
1678 The -e option works differently. If the -e option is not set, less be‐
1680 haves as if the -e option were set. If the -e option is set, less be‐
1681 haves as if the -E option were set.
1682 The -m option works differently. If the -m option is not set, the
1684 medium prompt is used, and it is prefixed with the string "--More--".
1685 If the -m option is set, the short prompt is used.
1686 The -n option acts like the -z option. The normal behavior of the -n
1688 option is unavailable in this mode.
1689 The parameter to the -p option is taken to be a less command rather
1691 than a search pattern.
1692 The LESS environment variable is ignored, and the MORE environment
1694 variable is used in its place.
1695
1697 Environment variables may be specified either in the system environment
1698 as usual, or in a lesskey(1) file. If environment variables are de‐
1699 fined in more than one place, variables defined in a local lesskey file
1700 take precedence over variables defined in the system environment, which
1701 take precedence over variables defined in the system-wide lesskey file.
1702 COLUMNS
1704 Sets the number of columns on the screen. Takes precedence over
1705 the number of columns specified by the TERM variable. (But if
1706 you have a windowing system which supports TIOCGWINSZ or
1707 WIOCGETD, the window system's idea of the screen size takes
1708 precedence over the LINES and COLUMNS environment variables.)
1709 EDITOR The name of the editor (used for the v command).
1711 HOME Name of the user's home directory (used to find a lesskey file
1713 on Unix and OS/2 systems).
1714 HOMEDRIVE, HOMEPATH
1716 Concatenation of the HOMEDRIVE and HOMEPATH environment vari‐
1717 ables is the name of the user's home directory if the HOME vari‐
1718 able is not set (only in the Windows version).
1719 INIT Name of the user's init directory (used to find a lesskey file
1721 on OS/2 systems).
1722 LANG Language for determining the character set.
1724 LC_CTYPE
1726 Language for determining the character set.
1727 LESS Options which are passed to less automatically.
1729 LESSANSIENDCHARS
1731 Characters which may end an ANSI color escape sequence (default
1732 "m").
1733 LESSANSIMIDCHARS
1735 Characters which may appear between the ESC character and the
1736 end character in an ANSI color escape sequence (default
1737 "0123456789:;[?!"'#%()*+ ".
1738 LESSBINFMT
1740 Format for displaying non-printable, non-control characters.
1741 LESSCHARDEF
1743 Defines a character set.
1744 LESSCHARSET
1746 Selects a predefined character set.
1747 LESSCLOSE
1749 Command line to invoke the (optional) input-postprocessor.
1750 LESSECHO
1752 Name of the lessecho program (default "lessecho"). The lessecho
1753 program is needed to expand metacharacters, such as * and ?, in
1754 filenames on Unix systems.
1755 LESSEDIT
1757 Editor prototype string (used for the v command). See discus‐
1758 sion under PROMPTS.
1759 LESSGLOBALTAGS
1761 Name of the command used by the -t option to find global tags.
1762 Normally should be set to "global" if your system has the glob‐
1763 al(1) command. If not set, global tags are not used.
1764 LESSHISTFILE
1766 Name of the history file used to remember search commands and
1767 shell commands between invocations of less. If set to "-" or
1768 "/dev/null", a history file is not used. The default is
1769 "$XDG_DATA_HOME/lesshst" or "$HOME/.lesshst" on Unix systems,
1770 "$HOME/_lesshst" on DOS and Windows systems, or
1771 "$HOME/lesshst.ini" or "$INIT/lesshst.ini" on OS/2 systems.
1772 LESSHISTSIZE
1774 The maximum number of commands to save in the history file. The
1775 default is 100.
1776 LESSKEYIN
1778 Name of the default lesskey source file.
1779 LESSKEY
1781 Name of the default lesskey binary file. (Not used if
1782 "$LESSKEYIN" exists.)
1783 LESSKEYIN_SYSTEM
1785 Name of the default system-wide lesskey source file.
1786 LESSKEY_SYSTEM
1788 Name of the default system-wide lesskey binary file. (Not used
1789 if "$LESSKEYIN_SYSTEM" exists.)
1790 LESSMETACHARS
1792 List of characters which are considered "metacharacters" by the
1793 shell.
1794 LESSMETAESCAPE
1796 Prefix which less will add before each metacharacter in a com‐
1797 mand sent to the shell. If LESSMETAESCAPE is an empty string,
1798 commands containing metacharacters will not be passed to the
1799 shell.
1800 LESSOPEN
1802 Command line to invoke the (optional) input-preprocessor.
1803 LESSSECURE
1805 Runs less in "secure" mode. See discussion under SECURITY.
1806 LESSSEPARATOR
1808 String to be appended to a directory name in filename comple‐
1809 tion.
1810 LESSUTFBINFMT
1812 Format for displaying non-printable Unicode code points.
1813 LESS_IS_MORE
1815 Emulate the more(1) command.
1816 LINES Sets the number of lines on the screen. Takes precedence over
1818 the number of lines specified by the TERM variable. (But if you
1819 have a windowing system which supports TIOCGWINSZ or WIOCGETD,
1820 the window system's idea of the screen size takes precedence
1821 over the LINES and COLUMNS environment variables.)
1822 MORE Options which are passed to less automatically when running in
1824 more compatible mode.
1825 PATH User's search path (used to find a lesskey file on MS-DOS and
1827 OS/2 systems).
1828 SHELL The shell used to execute the ! command, as well as to expand
1830 filenames.
1831 TERM The type of terminal on which less is being run.
1833 VISUAL The name of the editor (used for the v command).
1835
1837 lesskey(1)
1838
1840 Copyright (C) 1984-2021 Mark Nudelman
1841 less is part of the GNU project and is free software. You can redis‐
1843 tribute it and/or modify it under the terms of either (1) the GNU Gen‐
1844 eral Public License as published by the Free Software Foundation; or
1845 (2) the Less License. See the file README in the less distribution for
1846 more details regarding redistribution. You should have received a copy
1847 of the GNU General Public License along with the source for less; see
1848 the file COPYING. If not, write to the Free Software Foundation, 59
1849 Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should also
1850 have received a copy of the Less License; see the file LICENSE.
1851 less is distributed in the hope that it will be useful, but WITHOUT ANY
1853 WARRANTY; without even the implied warranty of MERCHANTABILITY or FIT‐
1854 NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
1855 more details.
1856
1858 Mark Nudelman
1859 Report bugs at https://github.com/gwsw/less/issues.
1860 For more information, see the less homepage at
1861 https://greenwoodsoftware.com/less
1862 Version 590: 03 Jun 2021 LESS(1)