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  1. LESS(1) LESS(1) NAME
  2. less - opposite of more SYNOPSIS
  3. less -?
  4. less --help
  5. less -V
  6. less --version
  7. less [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
  8. [-b space] [-h lines] [-j line] [-k keyfile]
  9. [-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
  10. [-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
  11. [-# shift] [+[+]cmd] [--] [filename]...
  12. (See the OPTIONS section for alternate option syntax with long option
  13. names.) DESCRIPTION
  14. Less is a program similar to more (1), but which allows backward move-
  15. ment in the file as well as forward movement. Also, less does not have
  16. to read the entire input file before starting, so with large input
  17. files it starts up faster than text editors like vi (1). Less uses
  18. termcap (or terminfo on some systems), so it can run on a variety of
  19. terminals. There is even limited support for hardcopy terminals. (On
  20. a hardcopy terminal, lines which should be printed at the top of the
  21. screen are prefixed with a caret.)
  22. Commands are based on both more and vi. Commands may be preceded by a
  23. decimal number, called N in the descriptions below. The number is used
  24. by some commands, as indicated. COMMANDS
  25. In the following descriptions, ^X means control-X. ESC stands for the
  26. ESCAPE key; for example ESC-v means the two character sequence
  27. "ESCAPE", then "v".
  28. h or H Help: display a summary of these commands. If you forget all
  29. the other commands, remember this one.
  30. SPACE or ^V or f or ^F
  31. Scroll forward N lines, default one window (see option -z
  32. below). If N is more than the screen size, only the final
  33. screenful is displayed. Warning: some systems use ^V as a spe-
  34. cial literalization character.
  35. z Like SPACE, but if N is specified, it becomes the new window
  36. size.
  37. ESC-SPACE
  38. Like SPACE, but scrolls a full screenful, even if it reaches
  39. end-of-file in the process.
  40. RETURN or ^N or e or ^E or j or ^J
  41. Scroll forward N lines, default 1. The entire N lines are dis-
  42. played, even if N is more than the screen size.
  43. d or ^D
  44. Scroll forward N lines, default one half of the screen size. If
  45. N is specified, it becomes the new default for subsequent d and
  46. u commands.
  47. b or ^B or ESC-v
  48. Scroll backward N lines, default one window (see option -z
  49. below). If N is more than the screen size, only the final
  50. screenful is displayed.
  51. w Like ESC-v, but if N is specified, it becomes the new window
  52. size.
  53. y or ^Y or ^P or k or ^K
  54. Scroll backward N lines, default 1. The entire N lines are dis-
  55. played, even if N is more than the screen size. Warning: some
  56. systems use ^Y as a special job control character.
  57. u or ^U
  58. Scroll backward N lines, default one half of the screen size.
  59. If N is specified, it becomes the new default for subsequent d
  60. and u commands.
  61. ESC-) or RIGHTARROW
  62. Scroll horizontally right N characters, default half the screen
  63. width (see the -# option). If a number N is specified, it
  64. becomes the default for future RIGHTARROW and LEFTARROW com-
  65. mands. While the text is scrolled, it acts as though the -S
  66. option (chop lines) were in effect.
  67. ESC-( or LEFTARROW
  68. Scroll horizontally left N characters, default half the screen
  69. width (see the -# option). If a number N is specified, it
  70. becomes the default for future RIGHTARROW and LEFTARROW com-
  71. mands.
  72. r or ^R or ^L
  73. Repaint the screen.
  74. R Repaint the screen, discarding any buffered input. Useful if
  75. the file is changing while it is being viewed.
  76. F Scroll forward, and keep trying to read when the end of file is
  77. reached. Normally this command would be used when already at
  78. the end of the file. It is a way to monitor the tail of a file
  79. which is growing while it is being viewed. (The behavior is
  80. similar to the "tail -f" command.)
  81. g or < or ESC-<
  82. Go to line N in the file, default 1 (beginning of file). (Warn-
  83. ing: this may be slow if N is large.)
  84. G or > or ESC->
  85. Go to line N in the file, default the end of the file. (Warn-
  86. ing: this may be slow if N is large, or if N is not specified
  87. and standard input, rather than a file, is being read.)
  88. p or % Go to a position N percent into the file. N should be between 0
  89. and 100, and may contain a decimal point.
  90. P Go to the line containing byte offset N in the file.
  91. { If a left curly bracket appears in the top line displayed on the
  92. screen, the { command will go to the matching right curly
  93. bracket. The matching right curly bracket is positioned on the
  94. bottom line of the screen. If there is more than one left curly
  95. bracket on the top line, a number N may be used to specify the
  96. N-th bracket on the line.
  97. } If a right curly bracket appears in the bottom line displayed on
  98. the screen, the } command will go to the matching left curly
  99. bracket. The matching left curly bracket is positioned on the
  100. top line of the screen. If there is more than one right curly
  101. bracket on the top line, a number N may be used to specify the
  102. N-th bracket on the line.
  103. ( Like {, but applies to parentheses rather than curly brackets.
  104. ) Like }, but applies to parentheses rather than curly brackets.
  105. [ Like {, but applies to square brackets rather than curly brack-
  106. ets.
  107. ] Like }, but applies to square brackets rather than curly brack-
  108. ets.
  109. ESC-^F Followed by two characters, acts like {, but uses the two char-
  110. acters as open and close brackets, respectively. For example,
  111. "ESC ^F < >" could be used to go forward to the > which matches
  112. the < in the top displayed line.
  113. ESC-^B Followed by two characters, acts like }, but uses the two char-
  114. acters as open and close brackets, respectively. For example,
  115. "ESC ^B < >" could be used to go backward to the < which matches
  116. the > in the bottom displayed line.
  117. m Followed by any lowercase letter, marks the current position
  118. with that letter.
  119. ' (Single quote.) Followed by any lowercase letter, returns to
  120. the position which was previously marked with that letter. Fol-
  121. lowed by another single quote, returns to the position at which
  122. the last "large" movement command was executed. Followed by a ^
  123. or $, jumps to the beginning or end of the file respectively.
  124. Marks are preserved when a new file is examined, so the ' com-
  125. mand can be used to switch between input files.
  126. ^X^X Same as single quote.
  127. /pattern
  128. Search forward in the file for the N-th line containing the pat-
  129. tern. N defaults to 1. The pattern is a regular expression, as
  130. recognized by the regular expression library supplied by your
  131. system. The search starts at the second line displayed (but see
  132. the -a and -j options, which change this).
  133. Certain characters are special if entered at the beginning of
  134. the pattern; they modify the type of search rather than become
  135. part of the pattern:
  136. ^N or !
  137. Search for lines which do NOT match the pattern.
  138. ^E or *
  139. Search multiple files. That is, if the search reaches
  140. the END of the current file without finding a match, the
  141. search continues in the next file in the command line
  142. list.
  143. ^F or @
  144. Begin the search at the first line of the FIRST file in
  145. the command line list, regardless of what is currently
  146. displayed on the screen or the settings of the -a or -j
  147. options.
  148. ^K Highlight any text which matches the pattern on the cur-
  149. rent screen, but don't move to the first match (KEEP cur-
  150. rent position).
  151. ^R Don't interpret regular expression metacharacters; that
  152. is, do a simple textual comparison.
  153. ?pattern
  154. Search backward in the file for the N-th line containing the
  155. pattern. The search starts at the line immediately before the
  156. top line displayed.
  157. Certain characters are special as in the / command:
  158. ^N or !
  159. Search for lines which do NOT match the pattern.
  160. ^E or *
  161. Search multiple files. That is, if the search reaches
  162. the beginning of the current file without finding a
  163. match, the search continues in the previous file in the
  164. command line list.
  165. ^F or @
  166. Begin the search at the last line of the last file in the
  167. command line list, regardless of what is currently dis-
  168. played on the screen or the settings of the -a or -j
  169. options.
  170. ^K As in forward searches.
  171. ^R As in forward searches.
  172. ESC-/pattern
  173. Same as "/*".
  174. ESC-?pattern
  175. Same as "?*".
  176. n Repeat previous search, for N-th line containing the last pat-
  177. tern. If the previous search was modified by ^N, the search is
  178. made for the N-th line NOT containing the pattern. If the pre-
  179. vious search was modified by ^E, the search continues in the
  180. next (or previous) file if not satisfied in the current file.
  181. If the previous search was modified by ^R, the search is done
  182. without using regular expressions. There is no effect if the
  183. previous search was modified by ^F or ^K.
  184. N Repeat previous search, but in the reverse direction.
  185. ESC-n Repeat previous search, but crossing file boundaries. The
  186. effect is as if the previous search were modified by *.
  187. ESC-N Repeat previous search, but in the reverse direction and cross-
  188. ing file boundaries.
  189. ESC-u Undo search highlighting. Turn off highlighting of strings
  190. matching the current search pattern. If highlighting is already
  191. off because of a previous ESC-u command, turn highlighting back
  192. on. Any search command will also turn highlighting back on.
  193. (Highlighting can also be disabled by toggling the -G option; in
  194. that case search commands do not turn highlighting back on.)
  195. :e [filename]
  196. Examine a new file. If the filename is missing, the "current"
  197. file (see the :n and :p commands below) from the list of files
  198. in the command line is re-examined. A percent sign (%) in the
  199. filename is replaced by the name of the current file. A pound
  200. sign (#) is replaced by the name of the previously examined
  201. file. However, two consecutive percent signs are simply
  202. replaced with a single percent sign. This allows you to enter a
  203. filename that contains a percent sign in the name. Similarly,
  204. two consecutive pound signs are replaced with a single pound
  205. sign. The filename is inserted into the command line list of
  206. files so that it can be seen by subsequent :n and :p commands.
  207. If the filename consists of several files, they are all inserted
  208. into the list of files and the first one is examined. If the
  209. filename contains one or more spaces, the entire filename should
  210. be enclosed in double quotes (also see the -" option).
  211. ^X^V or E
  212. Same as :e. Warning: some systems use ^V as a special literal-
  213. ization character. On such systems, you may not be able to use
  214. ^V.
  215. :n Examine the next file (from the list of files given in the com-
  216. mand line). If a number N is specified, the N-th next file is
  217. examined.
  218. :p Examine the previous file in the command line list. If a number
  219. N is specified, the N-th previous file is examined.
  220. :x Examine the first file in the command line list. If a number N
  221. is specified, the N-th file in the list is examined.
  222. :d Remove the current file from the list of files.
  223. t Go to the next tag, if there were more than one matches for the
  224. current tag. See the -t option for more details about tags.
  225. T Go to the previous tag, if there were more than one matches for
  226. the current tag.
  227. = or ^G or :f
  228. Prints some information about the file being viewed, including
  229. its name and the line number and byte offset of the bottom line
  230. being displayed. If possible, it also prints the length of the
  231. file, the number of lines in the file and the percent of the
  232. file above the last displayed line.
  233. - Followed by one of the command line option letters (see OPTIONS
  234. below), this will change the setting of that option and print a
  235. message describing the new setting. If a ^P (CONTROL-P) is
  236. entered immediately after the dash, the setting of the option is
  237. changed but no message is printed. If the option letter has a
  238. numeric value (such as -b or -h), or a string value (such as -P
  239. or -t), a new value may be entered after the option letter. If
  240. no new value is entered, a message describing the current set-
  241. ting is printed and nothing is changed.
  242. -- Like the - command, but takes a long option name (see OPTIONS
  243. below) rather than a single option letter. You must press
  244. RETURN after typing the option name. A ^P immediately after the
  245. second dash suppresses printing of a message describing the new
  246. setting, as in the - command.
  247. -+ Followed by one of the command line option letters this will
  248. reset the option to its default setting and print a message
  249. describing the new setting. (The "-+X" command does the same
  250. thing as "-+X" on the command line.) This does not work for
  251. string-valued options.
  252. --+ Like the -+ command, but takes a long option name rather than a
  253. single option letter.
  254. -! Followed by one of the command line option letters, this will
  255. reset the option to the "opposite" of its default setting and
  256. print a message describing the new setting. This does not work
  257. for numeric or string-valued options.
  258. --! Like the -! command, but takes a long option name rather than a
  259. single option letter.
  260. _ (Underscore.) Followed by one of the command line option let-
  261. ters, this will print a message describing the current setting
  262. of that option. The setting of the option is not changed.
  263. __ (Double underscore.) Like the _ (underscore) command, but takes
  264. a long option name rather than a single option letter. You must
  265. press RETURN after typing the option name.
  266. +cmd Causes the specified cmd to be executed each time a new file is
  267. examined. For example, +G causes less to initially display each
  268. file starting at the end rather than the beginning.
  269. V Prints the version number of less being run.
  270. q or Q or :q or :Q or ZZ
  271. Exits less.
  272. The following four commands may or may not be valid, depending on your
  273. particular installation.
  274. v Invokes an editor to edit the current file being viewed. The
  275. editor is taken from the environment variable VISUAL if defined,
  276. or EDITOR if VISUAL is not defined, or defaults to "vi" if nei-
  277. ther VISUAL nor EDITOR is defined. See also the discussion of
  278. LESSEDIT under the section on PROMPTS below.
  279. ! shell-command
  280. Invokes a shell to run the shell-command given. A percent sign
  281. (%) in the command is replaced by the name of the current file.
  282. A pound sign (#) is replaced by the name of the previously exam-
  283. ined file. "!!" repeats the last shell command. "!" with no
  284. shell command simply invokes a shell. On Unix systems, the
  285. shell is taken from the environment variable SHELL, or defaults
  286. to "sh". On MS-DOS and OS/2 systems, the shell is the normal
  287. command processor.
  288. | <m> shell-command
  289. <m> represents any mark letter. Pipes a section of the input
  290. file to the given shell command. The section of the file to be
  291. piped is between the first line on the current screen and the
  292. position marked by the letter. <m> may also be ^ or $ to indi-
  293. cate beginning or end of file respectively. If <m> is . or new-
  294. line, the current screen is piped.
  295. s filename
  296. Save the input to a file. This only works if the input is a
  297. pipe, not an ordinary file. OPTIONS
  298. Command line options are described below. Most options may be changed
  299. while less is running, via the "-" command.
  300. Most options may be given in one of two forms: either a dash followed
  301. by a single letter, or two dashes followed by a long option name. A
  302. long option name may be abbreviated as long as the abbreviation is
  303. unambiguous. For example, --quit-at-eof may be abbreviated --quit, but
  304. not --qui, since both --quit-at-eof and --quiet begin with --qui. Some
  305. long option names are in uppercase, such as --QUIT-AT-EOF, as distinct
  306. from --quit-at-eof. Such option names need only have their first let-
  307. ter capitalized; the remainder of the name may be in either case. For
  308. example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.
  309. Options are also taken from the environment variable "LESS". For exam-
  310. ple, to avoid typing "less -options ..." each time less is invoked, you
  311. might tell csh:
  312. setenv LESS "-options"
  313. or if you use sh:
  314. LESS="-options"; export LESS
  315. On MS-DOS, you don't need the quotes, but you should replace any per-
  316. cent signs in the options string by double percent signs.
  317. The environment variable is parsed before the command line, so command
  318. line options override the LESS environment variable. If an option
  319. appears in the LESS variable, it can be reset to its default value on
  320. the command line by beginning the command line option with "-+".
  321. For options like -P or -D which take a following string, a dollar sign
  322. ($) must be used to signal the end of the string. For example, to set
  323. two -D options on MS-DOS, you must have a dollar sign between them,
  324. like this:
  325. LESS="-Dn9.1$-Ds4.1"
  326. -? or --help
  327. This option displays a summary of the commands accepted by less
  328. (the same as the h command). (Depending on how your shell
  329. interprets the question mark, it may be necessary to quote the
  330. question mark, thus: "-\?".)
  331. -a or --search-skip-screen
  332. Causes searches to start after the last line displayed on the
  333. screen, thus skipping all lines displayed on the screen. By
  334. default, searches start at the second line on the screen (or
  335. after the last found line; see the -j option).
  336. -bn or --buffers=n
  337. Specifies the amount of buffer space less will use for each
  338. file, in units of kilobytes (1024 bytes). By default 64K of
  339. buffer space is used for each file (unless the file is a pipe;
  340. see the -B option). The -b option specifies instead that n
  341. kilobytes of buffer space should be used for each file. If n is
  342. -1, buffer space is unlimited; that is, the entire file can be
  343. read into memory.
  344. -B or --auto-buffers
  345. By default, when data is read from a pipe, buffers are allocated
  346. automatically as needed. If a large amount of data is read from
  347. the pipe, this can cause a large amount of memory to be allo-
  348. cated. The -B option disables this automatic allocation of
  349. buffers for pipes, so that only 64K (or the amount of space
  350. specified by the -b option) is used for the pipe. Warning: use
  351. of -B can result in erroneous display, since only the most
  352. recently viewed part of the piped data is kept in memory; any
  353. earlier data is lost.
  354. -c or --clear-screen
  355. Causes full screen repaints to be painted from the top line
  356. down. By default, full screen repaints are done by scrolling
  357. from the bottom of the screen.
  358. -C or --CLEAR-SCREEN
  359. Same as -c, for compatibility with older versions of less.
  360. -d or --dumb
  361. The -d option suppresses the error message normally displayed if
  362. the terminal is dumb; that is, lacks some important capability,
  363. such as the ability to clear the screen or scroll backward. The
  364. -d option does not otherwise change the behavior of less on a
  365. dumb terminal.
  366. -Dxcolor or --color=xcolor
  367. [MS-DOS only] Sets the color of the text displayed. x is a sin-
  368. gle character which selects the type of text whose color is
  369. being set: n=normal, s=standout, d=bold, u=underlined, k=blink.
  370. color is a pair of numbers separated by a period. The first
  371. number selects the foreground color and the second selects the
  372. background color of the text. A single number N is the same as
  373. N.0.
  374. -e or --quit-at-eof
  375. Causes less to automatically exit the second time it reaches
  376. end-of-file. By default, the only way to exit less is via the
  377. "q" command.
  378. -E or --QUIT-AT-EOF
  379. Causes less to automatically exit the first time it reaches end-
  380. of-file.
  381. -f or --force
  382. Forces non-regular files to be opened. (A non-regular file is a
  383. directory or a device special file.) Also suppresses the warn-
  384. ing message when a binary file is opened. By default, less will
  385. refuse to open non-regular files. Note that some operating sys-
  386. tems will not allow directories to be read, even if -f is set.
  387. -F or --quit-if-one-screen
  388. Causes less to automatically exit if the entire file can be dis-
  389. played on the first screen.
  390. -g or --hilite-search
  391. Normally, less will highlight ALL strings which match the last
  392. search command. The -g option changes this behavior to high-
  393. light only the particular string which was found by the last
  394. search command. This can cause less to run somewhat faster than
  395. the default.
  396. -G or --HILITE-SEARCH
  397. The -G option suppresses all highlighting of strings found by
  398. search commands.
  399. -hn or --max-back-scroll=n
  400. Specifies a maximum number of lines to scroll backward. If it
  401. is necessary to scroll backward more than n lines, the screen is
  402. repainted in a forward direction instead. (If the terminal does
  403. not have the ability to scroll backward, -h0 is implied.)
  404. -i or --ignore-case
  405. Causes searches to ignore case; that is, uppercase and lowercase
  406. are considered identical. This option is ignored if any upper-
  407. case letters appear in the search pattern; in other words, if a
  408. pattern contains uppercase letters, then that search does not
  409. ignore case.
  410. -I or --IGNORE-CASE
  411. Like -i, but searches ignore case even if the pattern contains
  412. uppercase letters.
  413. -jn or --jump-target=n
  414. Specifies a line on the screen where the "target" line is to be
  415. positioned. The target line is the line specified by any com-
  416. mand to search for a pattern, jump to a line number, jump to a
  417. file percentage or jump to a tag. The screen line may be speci-
  418. fied by a number: the top line on the screen is 1, the next is
  419. 2, and so on. The number may be negative to specify a line rel-
  420. ative to the bottom of the screen: the bottom line on the screen
  421. is -1, the second to the bottom is -2, and so on. Alternately,
  422. the screen line may be specified as a fraction of the height of
  423. the screen, starting with a decimal point: .5 is in the middle
  424. of the screen, .3 is three tenths down from the first line, and
  425. so on. If the line is specified as a fraction, the actual line
  426. number is recalculated if the terminal window is resized, so
  427. that the target line remains at the specified fraction of the
  428. screen height. If any form of the -j option is used, forward
  429. searches begin at the line immediately after the target line,
  430. and backward searches begin at the target line. For example, if
  431. "-j4" is used, the target line is the fourth line on the screen,
  432. so forward searches begin at the fifth line on the screen.
  433. -J or --status-column
  434. Displays a status column at the left edge of the screen. The
  435. status column shows the lines that matched the current search.
  436. The status column is also used if the -w or -W option is in
  437. effect.
  438. -kfilename or --lesskey-file=filename
  439. Causes less to open and interpret the named file as a lesskey
  440. (1) file. Multiple -k options may be specified. If the LESSKEY
  441. or LESSKEY_SYSTEM environment variable is set, or if a lesskey
  442. file is found in a standard place (see KEY BINDINGS), it is also
  443. used as a lesskey file.
  444. -K or --quit-on-intr
  445. Causes less to exit immediately when an interrupt character
  446. (usually ^C) is typed. Normally, an interrupt character causes
  447. less to stop whatever it is doing and return to its command
  448. prompt. Note that use of this option makes it impossible to
  449. return to the command prompt from the "F" command.
  450. -L or --no-lessopen
  451. Ignore the LESSOPEN environment variable (see the INPUT PRE-
  452. PROCESSOR section below). This option can be set from within
  453. less, but it will apply only to files opened subsequently, not
  454. to the file which is currently open.
  455. -m or --long-prompt
  456. Causes less to prompt verbosely (like more), with the percent
  457. into the file. By default, less prompts with a colon.
  458. -M or --LONG-PROMPT
  459. Causes less to prompt even more verbosely than more.
  460. -n or --line-numbers
  461. Suppresses line numbers. The default (to use line numbers) may
  462. cause less to run more slowly in some cases, especially with a
  463. very large input file. Suppressing line numbers with the -n
  464. option will avoid this problem. Using line numbers means: the
  465. line number will be displayed in the verbose prompt and in the =
  466. command, and the v command will pass the current line number to
  467. the editor (see also the discussion of LESSEDIT in PROMPTS
  468. below).
  469. -N or --LINE-NUMBERS
  470. Causes a line number to be displayed at the beginning of each
  471. line in the display.
  472. -ofilename or --log-file=filename
  473. Causes less to copy its input to the named file as it is being
  474. viewed. This applies only when the input file is a pipe, not an
  475. ordinary file. If the file already exists, less will ask for
  476. confirmation before overwriting it.
  477. -Ofilename or --LOG-FILE=filename
  478. The -O option is like -o, but it will overwrite an existing file
  479. without asking for confirmation.
  480. If no log file has been specified, the -o and -O options can be
  481. used from within less to specify a log file. Without a file
  482. name, they will simply report the name of the log file. The "s"
  483. command is equivalent to specifying -o from within less.
  484. -ppattern or --pattern=pattern
  485. The -p option on the command line is equivalent to specifying
  486. +/pattern; that is, it tells less to start at the first occur-
  487. rence of pattern in the file.
  488. -Pprompt or --prompt=prompt
  489. Provides a way to tailor the three prompt styles to your own
  490. preference. This option would normally be put in the LESS envi-
  491. ronment variable, rather than being typed in with each less com-
  492. mand. Such an option must either be the last option in the LESS
  493. variable, or be terminated by a dollar sign. -Ps followed by a
  494. string changes the default (short) prompt to that string. -Pm
  495. changes the medium (-m) prompt. -PM changes the long (-M)
  496. prompt. -Ph changes the prompt for the help screen. -P=
  497. changes the message printed by the = command. -Pw changes the
  498. message printed while waiting for data (in the F command). All
  499. prompt strings consist of a sequence of letters and special
  500. escape sequences. See the section on PROMPTS for more details.
  501. -q or --quiet or --silent
  502. Causes moderately "quiet" operation: the terminal bell is not
  503. rung if an attempt is made to scroll past the end of the file or
  504. before the beginning of the file. If the terminal has a "visual
  505. bell", it is used instead. The bell will be rung on certain
  506. other errors, such as typing an invalid character. The default
  507. is to ring the terminal bell in all such cases.
  508. -Q or --QUIET or --SILENT
  509. Causes totally "quiet" operation: the terminal bell is never
  510. rung.
  511. -r or --raw-control-chars
  512. Causes "raw" control characters to be displayed. The default is
  513. to display control characters using the caret notation; for
  514. example, a control-A (octal 001) is displayed as "^A". Warning:
  515. when the -r option is used, less cannot keep track of the actual
  516. appearance of the screen (since this depends on how the screen
  517. responds to each type of control character). Thus, various dis-
  518. play problems may result, such as long lines being split in the
  519. wrong place.
  520. -R or --RAW-CONTROL-CHARS
  521. Like -r, but only ANSI "color" escape sequences are output in
  522. "raw" form. Unlike -r, the screen appearance is maintained cor-
  523. rectly in most cases. ANSI "color" escape sequences are
  524. sequences of the form:
  525. ESC [ ... m
  526. where the "..." is zero or more color specification characters
  527. For the purpose of keeping track of screen appearance, ANSI
  528. color escape sequences are assumed to not move the cursor. You
  529. can make less think that characters other than "m" can end ANSI
  530. color escape sequences by setting the environment variable
  531. LESSANSIENDCHARS to the list of characters which can end a color
  532. escape sequence. And you can make less think that characters
  533. other than the standard ones may appear between the ESC and the
  534. m by setting the environment variable LESSANSIMIDCHARS to the
  535. list of characters which can appear.
  536. -s or --squeeze-blank-lines
  537. Causes consecutive blank lines to be squeezed into a single
  538. blank line. This is useful when viewing nroff output.
  539. -S or --chop-long-lines
  540. Causes lines longer than the screen width to be chopped rather
  541. than folded. That is, the portion of a long line that does not
  542. fit in the screen width is not shown. The default is to fold
  543. long lines; that is, display the remainder on the next line.
  544. -ttag or --tag=tag
  545. The -t option, followed immediately by a TAG, will edit the file
  546. containing that tag. For this to work, tag information must be
  547. available; for example, there may be a file in the current
  548. directory called "tags", which was previously built by ctags (1)
  549. or an equivalent command. If the environment variable LESSGLOB-
  550. ALTAGS is set, it is taken to be the name of a command compati-
  551. ble with global (1), and that command is executed to find the
  552. tag. (See http://www.gnu.org/software/global/global.html). The
  553. -t option may also be specified from within less (using the -
  554. command) as a way of examining a new file. The command ":t" is
  555. equivalent to specifying -t from within less.
  556. -Ttagsfile or --tag-file=tagsfile
  557. Specifies a tags file to be used instead of "tags".
  558. -u or --underline-special
  559. Causes backspaces and carriage returns to be treated as print-
  560. able characters; that is, they are sent to the terminal when
  561. they appear in the input.
  562. -U or --UNDERLINE-SPECIAL
  563. Causes backspaces, tabs and carriage returns to be treated as
  564. control characters; that is, they are handled as specified by
  565. the -r option.
  566. By default, if neither -u nor -U is given, backspaces which
  567. appear adjacent to an underscore character are treated spe-
  568. cially: the underlined text is displayed using the terminal's
  569. hardware underlining capability. Also, backspaces which appear
  570. between two identical characters are treated specially: the
  571. overstruck text is printed using the terminal's hardware bold-
  572. face capability. Other backspaces are deleted, along with the
  573. preceding character. Carriage returns immediately followed by a
  574. newline are deleted. other carriage returns are handled as
  575. specified by the -r option. Text which is overstruck or under-
  576. lined can be searched for if neither -u nor -U is in effect.
  577. -V or --version
  578. Displays the version number of less.
  579. -w or --hilite-unread
  580. Temporarily highlights the first "new" line after a forward
  581. movement of a full page. The first "new" line is the line imme-
  582. diately following the line previously at the bottom of the
  583. screen. Also highlights the target line after a g or p command.
  584. The highlight is removed at the next command which causes move-
  585. ment. The entire line is highlighted, unless the -J option is
  586. in effect, in which case only the status column is highlighted.
  587. -W or --HILITE-UNREAD
  588. Like -w, but temporarily highlights the first new line after any
  589. forward movement command larger than one line.
  590. -xn,... or --tabs=n,...
  591. Sets tab stops. If only one n is specified, tab stops are set
  592. at multiples of n. If multiple values separated by commas are
  593. specified, tab stops are set at those positions, and then con-
  594. tinue with the same spacing as the last two. For example,
  595. -x9,17 will set tabs at positions 9, 17, 25, 33, etc. The
  596. default for n is 8.
  597. -X or --no-init
  598. Disables sending the termcap initialization and deinitialization
  599. strings to the terminal. This is sometimes desirable if the
  600. deinitialization string does something unnecessary, like clear-
  601. ing the screen.
  602. -yn or --max-forw-scroll=n
  603. Specifies a maximum number of lines to scroll forward. If it is
  604. necessary to scroll forward more than n lines, the screen is
  605. repainted instead. The -c or -C option may be used to repaint
  606. from the top of the screen if desired. By default, any forward
  607. movement causes scrolling.
  608. -[z]n or --window=n
  609. Changes the default scrolling window size to n lines. The
  610. default is one screenful. The z and w commands can also be used
  611. to change the window size. The "z" may be omitted for compati-
  612. bility with some versions of more. If the number n is negative,
  613. it indicates n lines less than the current screen size. For
  614. example, if the screen is 24 lines, -z-4 sets the scrolling win-
  615. dow to 20 lines. If the screen is resized to 40 lines, the
  616. scrolling window automatically changes to 36 lines.
  617. -"cc or --quotes=cc
  618. Changes the filename quoting character. This may be necessary
  619. if you are trying to name a file which contains both spaces and
  620. quote characters. Followed by a single character, this changes
  621. the quote character to that character. Filenames containing a
  622. space should then be surrounded by that character rather than by
  623. double quotes. Followed by two characters, changes the open
  624. quote to the first character, and the close quote to the second
  625. character. Filenames containing a space should then be preceded
  626. by the open quote character and followed by the close quote
  627. character. Note that even after the quote characters are
  628. changed, this option remains -" (a dash followed by a double
  629. quote).
  630. -~ or --tilde
  631. Normally lines after end of file are displayed as a single tilde
  632. (~). This option causes lines after end of file to be displayed
  633. as blank lines.
  634. -# or --shift
  635. Specifies the default number of positions to scroll horizontally
  636. in the RIGHTARROW and LEFTARROW commands. If the number speci-
  637. fied is zero, it sets the default number of positions to one
  638. half of the screen width.
  639. --no-keypad
  640. Disables sending the keypad initialization and deinitialization
  641. strings to the terminal. This is sometimes useful if the keypad
  642. strings make the numeric keypad behave in an undesirable manner.
  643. --follow-name
  644. Normally, if the input file is renamed while an F command is
  645. executing, less will continue to display the contents of the
  646. original file despite its name change. If --follow-name is
  647. specified, during an F command less will periodically attempt to
  648. reopen the file by name. If the reopen succeeds and the file is
  649. a different file from the original (which means that a new file
  650. has been created with the same name as the original (now
  651. renamed) file), less will display the contents of that new file.
  652. -- A command line argument of "--" marks the end of option argu-
  653. ments. Any arguments following this are interpreted as file-
  654. names. This can be useful when viewing a file whose name begins
  655. with a "-" or "+".
  656. + If a command line option begins with +, the remainder of that
  657. option is taken to be an initial command to less. For example,
  658. +G tells less to start at the end of the file rather than the
  659. beginning, and +/xyz tells it to start at the first occurrence
  660. of "xyz" in the file. As a special case, +<number> acts like
  661. +<number>g; that is, it starts the display at the specified line
  662. number (however, see the caveat under the "g" command above).
  663. If the option starts with ++, the initial command applies to
  664. every file being viewed, not just the first one. The + command
  665. described previously may also be used to set (or change) an ini-
  666. tial command for every file. LINE EDITING
  667. When entering command line at the bottom of the screen (for example, a
  668. filename for the :e command, or the pattern for a search command), cer-
  669. tain keys can be used to manipulate the command line. Most commands
  670. have an alternate form in [ brackets ] which can be used if a key does
  671. not exist on a particular keyboard. (Note that the forms beginning
  672. with ESC do not work in some MS-DOS and Windows systems because ESC is
  673. the line erase character.) Any of these special keys may be entered
  674. literally by preceding it with the "literal" character, either ^V or
  675. ^A. A backslash itself may also be entered literally by entering two
  676. backslashes.
  677. LEFTARROW [ ESC-h ]
  678. Move the cursor one space to the left.
  679. RIGHTARROW [ ESC-l ]
  680. Move the cursor one space to the right.
  681. ^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
  682. (That is, CONTROL and LEFTARROW simultaneously.) Move the cur-
  683. sor one word to the left.
  684. ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
  685. (That is, CONTROL and RIGHTARROW simultaneously.) Move the cur-
  686. sor one word to the right.
  687. HOME [ ESC-0 ]
  688. Move the cursor to the beginning of the line.
  689. END [ ESC-$ ]
  690. Move the cursor to the end of the line.
  691. BACKSPACE
  692. Delete the character to the left of the cursor, or cancel the
  693. command if the command line is empty.
  694. DELETE or [ ESC-x ]
  695. Delete the character under the cursor.
  696. ^BACKSPACE [ ESC-BACKSPACE ]
  697. (That is, CONTROL and BACKSPACE simultaneously.) Delete the
  698. word to the left of the cursor.
  699. ^DELETE [ ESC-X or ESC-DELETE ]
  700. (That is, CONTROL and DELETE simultaneously.) Delete the word
  701. under the cursor.
  702. UPARROW [ ESC-k ]
  703. Retrieve the previous command line.
  704. DOWNARROW [ ESC-j ]
  705. Retrieve the next command line.
  706. TAB Complete the partial filename to the left of the cursor. If it
  707. matches more than one filename, the first match is entered into
  708. the command line. Repeated TABs will cycle thru the other
  709. matching filenames. If the completed filename is a directory, a
  710. "/" is appended to the filename. (On MS-DOS systems, a "\" is
  711. appended.) The environment variable LESSSEPARATOR can be used
  712. to specify a different character to append to a directory name.
  713. BACKTAB [ ESC-TAB ]
  714. Like, TAB, but cycles in the reverse direction thru the matching
  715. filenames.
  716. ^L Complete the partial filename to the left of the cursor. If it
  717. matches more than one filename, all matches are entered into the
  718. command line (if they fit).
  719. ^U (Unix and OS/2) or ESC (MS-DOS)
  720. Delete the entire command line, or cancel the command if the
  721. command line is empty. If you have changed your line-kill char-
  722. acter in Unix to something other than ^U, that character is used
  723. instead of ^U. KEY BINDINGS
  724. You may define your own less commands by using the program lesskey (1)
  725. to create a lesskey file. This file specifies a set of command keys
  726. and an action associated with each key. You may also use lesskey to
  727. change the line-editing keys (see LINE EDITING), and to set environment
  728. variables. If the environment variable LESSKEY is set, less uses that
  729. as the name of the lesskey file. Otherwise, less looks in a standard
  730. place for the lesskey file: On Unix systems, less looks for a lesskey
  731. file called "$HOME/.less". On MS-DOS and Windows systems, less looks
  732. for a lesskey file called "$HOME/_less", and if it is not found there,
  733. then looks for a lesskey file called "_less" in any directory specified
  734. in the PATH environment variable. On OS/2 systems, less looks for a
  735. lesskey file called "$HOME/less.ini", and if it is not found, then
  736. looks for a lesskey file called "less.ini" in any directory specified
  737. in the INIT environment variable, and if it not found there, then looks
  738. for a lesskey file called "less.ini" in any directory specified in the
  739. PATH environment variable. See the lesskey manual page for more
  740. details.
  741. A system-wide lesskey file may also be set up to provide key bindings.
  742. If a key is defined in both a local lesskey file and in the system-wide
  743. file, key bindings in the local file take precedence over those in the
  744. system-wide file. If the environment variable LESSKEY_SYSTEM is set,
  745. less uses that as the name of the system-wide lesskey file. Otherwise,
  746. less looks in a standard place for the system-wide lesskey file: On
  747. Unix systems, the system-wide lesskey file is /usr/local/etc/sysless.
  748. (However, if less was built with a different sysconf directory than
  749. /usr/local/etc, that directory is where the sysless file is found.) On
  750. MS-DOS and Windows systems, the system-wide lesskey file is c:\_sys-
  751. less. On OS/2 systems, the system-wide lesskey file is c:\sysless.ini. INPUT
  752. PREPROCESSOR
  753. You may define an "input preprocessor" for less. Before less opens a
  754. file, it first gives your input preprocessor a chance to modify the way
  755. the contents of the file are displayed. An input preprocessor is sim-
  756. ply an executable program (or shell script), which writes the contents
  757. of the file to a different file, called the replacement file. The con-
  758. tents of the replacement file are then displayed in place of the con-
  759. tents of the original file. However, it will appear to the user as if
  760. the original file is opened; that is, less will display the original
  761. filename as the name of the current file.
  762. An input preprocessor receives one command line argument, the original
  763. filename, as entered by the user. It should create the replacement
  764. file, and when finished, print the name of the replacement file to its
  765. standard output. If the input preprocessor does not output a replace-
  766. ment filename, less uses the original file, as normal. The input pre-
  767. processor is not called when viewing standard input. To set up an
  768. input preprocessor, set the LESSOPEN environment variable to a command
  769. line which will invoke your input preprocessor. This command line
  770. should include one occurrence of the string "%s", which will be
  771. replaced by the filename when the input preprocessor command is
  772. invoked.
  773. When less closes a file opened in such a way, it will call another pro-
  774. gram, called the input postprocessor, which may perform any desired
  775. clean-up action (such as deleting the replacement file created by
  776. LESSOPEN). This program receives two command line arguments, the orig-
  777. inal filename as entered by the user, and the name of the replacement
  778. file. To set up an input postprocessor, set the LESSCLOSE environment
  779. variable to a command line which will invoke your input postprocessor.
  780. It may include two occurrences of the string "%s"; the first is
  781. replaced with the original name of the file and the second with the
  782. name of the replacement file, which was output by LESSOPEN.
  783. For example, on many Unix systems, these two scripts will allow you to
  784. keep files in compressed format, but still let less view them directly:
  785. lessopen.sh:
  786. #! /bin/sh
  787. case "$1" in
  788. *.Z) uncompress -
  789. if [ -s /tmp/less.$$ ]; then
  790. echo /tmp/less.$$
  791. else
  792. rm -f /tmp/less.$$
  793. fi
  794. ;;
  795. esac
  796. lessclose.sh:
  797. #! /bin/sh
  798. rm $2
  799. To use these scripts, put them both where they can be executed and set
  800. LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s". More
  801. complex LESSOPEN and LESSCLOSE scripts may be written to accept other
  802. types of compressed files, and so on.
  803. It is also possible to set up an input preprocessor to pipe the file
  804. data directly to less, rather than putting the data into a replacement
  805. file. This avoids the need to decompress the entire file before start-
  806. ing to view it. An input preprocessor that works this way is called an
  807. input pipe. An input pipe, instead of writing the name of a replace-
  808. ment file on its standard output, writes the entire contents of the
  809. replacement file on its standard output. If the input pipe does not
  810. write any characters on its standard output, then there is no replace-
  811. ment file and less uses the original file, as normal. To use an input
  812. pipe, make the first character in the LESSOPEN environment variable a
  813. vertical bar (|) to signify that the input preprocessor is an input
  814. pipe.
  815. For example, on many Unix systems, this script will work like the pre-
  816. vious example scripts:
  817. lesspipe.sh:
  818. #! /bin/sh
  819. case "$1" in
  820. *.Z) uncompress -c $1 2>/dev/null
  821. ;;
  822. esac
  823. To use this script, put it where it can be executed and set
  824. LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE
  825. postprocessor can be used, but it is usually not necessary since there
  826. is no replacement file to clean up. In this case, the replacement file
  827. name passed to the LESSCLOSE postprocessor is "-". NATIONAL CHARACTER SETS
  828. There are three types of characters in the input file:
  829. normal characters
  830. can be displayed directly to the screen.
  831. control characters
  832. should not be displayed directly, but are expected to be found
  833. in ordinary text files (such as backspace and tab).
  834. binary characters
  835. should not be displayed directly and are not expected to be
  836. found in text files.
  837. A "character set" is simply a description of which characters are to be
  838. considered normal, control, and binary. The LESSCHARSET environment
  839. variable may be used to select a character set. Possible values for
  840. LESSCHARSET are:
  841. ascii BS, TAB, NL, CR, and formfeed are control characters, all chars
  842. with values between 32 and 126 are normal, and all others are
  843. binary.
  844. iso8859
  845. Selects an ISO 8859 character set. This is the same as ASCII,
  846. except characters between 160 and 255 are treated as normal
  847. characters.
  848. latin1 Same as iso8859.
  849. latin9 Same as iso8859.
  850. dos Selects a character set appropriate for MS-DOS.
  851. ebcdic Selects an EBCDIC character set.
  852. IBM-1047
  853. Selects an EBCDIC character set used by OS/390 Unix Services.
  854. This is the EBCDIC analogue of latin1. You get similar results
  855. by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
  856. environment.
  857. koi8-r Selects a Russian character set.
  858. next Selects a character set appropriate for NeXT computers.
  859. utf-8 Selects the UTF-8 encoding of the ISO 10646 character set.
  860. UTF-8 is special in that it supports multi-byte characters in
  861. the input file. It is the only character set that supports
  862. multi-byte characters.
  863. windows
  864. Selects a character set appropriate for Microsoft Windows (cp
  865. 1251).
  866. In rare cases, it may be desired to tailor less to use a character set
  867. other than the ones definable by LESSCHARSET. In this case, the envi-
  868. ronment variable LESSCHARDEF can be used to define a character set. It
  869. should be set to a string where each character in the string represents
  870. one character in the character set. The character "." is used for a
  871. normal character, "c" for control, and "b" for binary. A decimal num-
  872. ber may be used for repetition. For example, "bccc4b." would mean
  873. character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are
  874. binary, and 8 is normal. All characters after the last are taken to be
  875. the same as the last, so characters 9 through 255 would be normal.
  876. (This is an example, and does not necessarily represent any real char-
  877. acter set.)
  878. This table shows the value of LESSCHARDEF which is equivalent to each
  879. of the possible values for LESSCHARSET:
  880. ascii 8bcccbcc18b95.b
  881. dos 8bcccbcc12bc5b95.b.
  882. ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
  883. 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
  884. IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
  885. 191.b
  886. iso8859 8bcccbcc18b95.33b.
  887. koi8-r 8bcccbcc18b95.b128.
  888. latin1 8bcccbcc18b95.33b.
  889. next 8bcccbcc18b95.bb125.bb
  890. If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings
  891. "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or
  892. LANG environment variables, then the default character set is utf-8.
  893. If that string is not found, but your system supports the setlocale
  894. interface, less will use setlocale to determine the character set.
  895. setlocale is controlled by setting the LANG or LC_CTYPE environment
  896. variables.
  897. Finally, if the setlocale interface is also not available, the default
  898. character set is latin1.
  899. Control and binary characters are displayed in standout (reverse
  900. video). Each such character is displayed in caret notation if possible
  901. (e.g. ^A for control-A). Caret notation is used only if inverting the
  902. 0100 bit results in a normal printable character. Otherwise, the char-
  903. acter is displayed as a hex number in angle brackets. This format can
  904. be changed by setting the LESSBINFMT environment variable. LESSBINFMT
  905. may begin with a "*" and one character to select the display attribute:
  906. "*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout,
  907. and "*n" is normal. If LESSBINFMT does not begin with a "*", normal
  908. attribute is assumed. The remainder of LESSBINFMT is a string which
  909. may include one printf-style escape sequence (a % followed by x, X, o,
  910. d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters
  911. are displayed in underlined hexadecimal surrounded by brackets. The
  912. default if no LESSBINFMT is specified is "*s<%X>". The default if no
  913. LESSBINFMT is specified is "*s<%02X>". Warning: the result of expand-
  914. ing the character via LESSBINFMT must be less than 31 characters.
  915. When the character set is utf-8, the LESSUTFBINFMT environment variable
  916. acts similarly to LESSBINFMT but it applies to Unicode code points that
  917. were successfully decoded but are unsuitable for display (e.g., unas-
  918. signed code points). Its default value is "<U+%04lX>". Note that
  919. LESSUTFBINFMT and LESSBINFMT share their display attribute setting
  920. ("*x") so specifying one will affect both; LESSUTFBINFMT is read after
  921. LESSBINFMT so its setting, if any, will have priority. Problematic
  922. octets in a UTF-8 file (octets of a truncated sequence, octets of a
  923. complete but non-shortest form sequence, illegal octets, and stray
  924. trailing octets) are displayed individually using LESSBINFMT so as to
  925. facilitate diagnostic of how the UTF-8 file is ill-formed. PROMPTS
  926. The -P option allows you to tailor the prompt to your preference. The
  927. string given to the -P option replaces the specified prompt string.
  928. Certain characters in the string are interpreted specially. The prompt
  929. mechanism is rather complicated to provide flexibility, but the ordi-
  930. nary user need not understand the details of constructing personalized
  931. prompt strings.
  932. A percent sign followed by a single character is expanded according to
  933. what the following character is:
  934. %bX Replaced by the byte offset into the current input file. The b
  935. is followed by a single character (shown as X above) which spec-
  936. ifies the line whose byte offset is to be used. If the charac-
  937. ter is a "t", the byte offset of the top line in the display is
  938. used, an "m" means use the middle line, a "b" means use the bot-
  939. tom line, a "B" means use the line just after the bottom line,
  940. and a "j" means use the "target" line, as specified by the -j
  941. option.
  942. %B Replaced by the size of the current input file.
  943. %c Replaced by the column number of the text appearing in the first
  944. column of the screen.
  945. %dX Replaced by the page number of a line in the input file. The
  946. line to be used is determined by the X, as with the %b option.
  947. %D Replaced by the number of pages in the input file, or equiva-
  948. lently, the page number of the last line in the input file.
  949. %E Replaced by the name of the editor (from the VISUAL environment
  950. variable, or the EDITOR environment variable if VISUAL is not
  951. defined). See the discussion of the LESSEDIT feature below.
  952. %f Replaced by the name of the current input file.
  953. %i Replaced by the index of the current file in the list of input
  954. files.
  955. %lX Replaced by the line number of a line in the input file. The
  956. line to be used is determined by the X, as with the %b option.
  957. %L Replaced by the line number of the last line in the input file.
  958. %m Replaced by the total number of input files.
  959. %pX Replaced by the percent into the current input file, based on
  960. byte offsets. The line used is determined by the X as with the
  961. %b option.
  962. %PX Replaced by the percent into the current input file, based on
  963. line numbers. The line used is determined by the X as with the
  964. %b option.
  965. %s Same as %B.
  966. %t Causes any trailing spaces to be removed. Usually used at the
  967. end of the string, but may appear anywhere.
  968. %x Replaced by the name of the next input file in the list.
  969. If any item is unknown (for example, the file size if input is a pipe),
  970. a question mark is printed instead.
  971. The format of the prompt string can be changed depending on certain
  972. conditions. A question mark followed by a single character acts like
  973. an "IF": depending on the following character, a condition is evalu-
  974. ated. If the condition is true, any characters following the question
  975. mark and condition character, up to a period, are included in the
  976. prompt. If the condition is false, such characters are not included.
  977. A colon appearing between the question mark and the period can be used
  978. to establish an "ELSE": any characters between the colon and the period
  979. are included in the string if and only if the IF condition is false.
  980. Condition characters (which follow a question mark) may be:
  981. ?a True if any characters have been included in the prompt so far.
  982. ?bX True if the byte offset of the specified line is known.
  983. ?B True if the size of current input file is known.
  984. ?c True if the text is horizontally shifted (%c is not zero).
  985. ?dX True if the page number of the specified line is known.
  986. ?e True if at end-of-file.
  987. ?f True if there is an input filename (that is, if input is not a
  988. pipe).
  989. ?lX True if the line number of the specified line is known.
  990. ?L True if the line number of the last line in the file is known.
  991. ?m True if there is more than one input file.
  992. ?n True if this is the first prompt in a new input file.
  993. ?pX True if the percent into the current input file, based on byte
  994. offsets, of the specified line is known.
  995. ?PX True if the percent into the current input file, based on line
  996. numbers, of the specified line is known.
  997. ?s Same as "?B".
  998. ?x True if there is a next input file (that is, if the current
  999. input file is not the last one).
  1000. Any characters other than the special ones (question mark, colon,
  1001. period, percent, and backslash) become literally part of the prompt.
  1002. Any of the special characters may be included in the prompt literally
  1003. by preceding it with a backslash.
  1004. Some examples:
  1005. ?f%f:Standard input.
  1006. This prompt prints the filename, if known; otherwise the string "Stan-
  1007. dard input".
  1008. ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
  1009. This prompt would print the filename, if known. The filename is fol-
  1010. lowed by the line number, if known, otherwise the percent if known,
  1011. otherwise the byte offset if known. Otherwise, a dash is printed.
  1012. Notice how each question mark has a matching period, and how the %
  1013. after the %pt is included literally by escaping it with a backslash.
  1014. ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t
  1015. This prints the filename if this is the first prompt in a file, fol-
  1016. lowed by the "file N of N" message if there is more than one input
  1017. file. Then, if we are at end-of-file, the string "(END)" is printed
  1018. followed by the name of the next file, if there is one. Finally, any
  1019. trailing spaces are truncated. This is the default prompt. For refer-
  1020. ence, here are the defaults for the other two prompts (-m and -M
  1021. respectively). Each is broken into two lines here for readability
  1022. only.
  1023. ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
  1024. ?pB%pB\%:byte %bB?s/%s...%t
  1025. ?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
  1026. byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
  1027. And here is the default message produced by the = command:
  1028. ?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
  1029. byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
  1030. The prompt expansion features are also used for another purpose: if an
  1031. environment variable LESSEDIT is defined, it is used as the command to
  1032. be executed when the v command is invoked. The LESSEDIT string is
  1033. expanded in the same way as the prompt strings. The default value for
  1034. LESSEDIT is:
  1035. %E ?lm+%lm. %f
  1036. Note that this expands to the editor name, followed by a + and the line
  1037. number, followed by the file name. If your editor does not accept the
  1038. "+linenumber" syntax, or has other differences in invocation syntax,
  1039. the LESSEDIT variable can be changed to modify this default. SECURITY
  1040. When the environment variable LESSSECURE is set to 1, less runs in a
  1041. "secure" mode. This means these features are disabled:
  1042. ! the shell command
  1043. | the pipe command
  1044. :e the examine command.
  1045. v the editing command
  1046. s -o log files
  1047. -k use of lesskey files
  1048. -t use of tags files
  1049. metacharacters in filenames, such as *
  1050. filename completion (TAB, ^L)
  1051. Less can also be compiled to be permanently in "secure" mode. COMPATIBILITY WITH MORE
  1052. If the environment variable LESS_IS_MORE is set to 1, or if the program
  1053. is invoked via a file link named "more", less behaves (mostly) in con-
  1054. formance with the POSIX "more" command specification. In this mode,
  1055. less behaves differently in these ways:
  1056. The -e option works differently. If the -e option is not set, less
  1057. behaves as if the -E option were set. If the -e option is set, less
  1058. behaves as if the -e and -F options were set.
  1059. The -m option works differently. If the -m option is not set, the
  1060. medium prompt is used, and it is prefixed with the string "--More--".
  1061. If the -m option is set, the short prompt is used.
  1062. The -n option acts like the -z option. The normal behavior of the -n
  1063. option is unavailable in this mode.
  1064. The parameter to the -p option is taken to be a less command rather
  1065. than a search pattern.
  1066. The LESS environment variable is ignored, and the MORE environment
  1067. variable is used in its place. ENVIRONMENT VARIABLES
  1068. Environment variables may be specified either in the system environment
  1069. as usual, or in a lesskey (1) file. If environment variables are
  1070. defined in more than one place, variables defined in a local lesskey
  1071. file take precedence over variables defined in the system environment,
  1072. which take precedence over variables defined in the system-wide lesskey
  1073. file.
  1074. COLUMNS
  1075. Sets the number of columns on the screen. Takes precedence over
  1076. the number of columns specified by the TERM variable. (But if
  1077. you have a windowing system which supports TIOCGWINSZ or
  1078. WIOCGETD, the window system's idea of the screen size takes
  1079. precedence over the LINES and COLUMNS environment variables.)
  1080. EDITOR The name of the editor (used for the v command).
  1081. HOME Name of the user's home directory (used to find a lesskey file
  1082. on Unix and OS/2 systems).
  1083. HOMEDRIVE, HOMEPATH
  1084. Concatenation of the HOMEDRIVE and HOMEPATH environment vari-
  1085. ables is the name of the user's home directory if the HOME vari-
  1086. able is not set (only in the Windows version).
  1087. INIT Name of the user's init directory (used to find a lesskey file
  1088. on OS/2 systems).
  1089. LANG Language for determining the character set.
  1090. LC_CTYPE
  1091. Language for determining the character set.
  1092. LESS Options which are passed to less automatically.
  1093. LESSANSIENDCHARS
  1094. Characters which may end an ANSI color escape sequence (default
  1095. "m").
  1096. LESSANSIMIDCHARS
  1097. Characters which may appear between the ESC character and the
  1098. end character in an ANSI color escape sequence (default
  1099. "0123456789;[?!"'#%()*+ ".
  1100. LESSBINFMT
  1101. Format for displaying non-printable, non-control characters.
  1102. LESSCHARDEF
  1103. Defines a character set.
  1104. LESSCHARSET
  1105. Selects a predefined character set.
  1106. LESSCLOSE
  1107. Command line to invoke the (optional) input-postprocessor.
  1108. LESSECHO
  1109. Name of the lessecho program (default "lessecho"). The lessecho
  1110. program is needed to expand metacharacters, such as * and ?, in
  1111. filenames on Unix systems.
  1112. LESSEDIT
  1113. Editor prototype string (used for the v command). See discus-
  1114. sion under PROMPTS.
  1115. LESSGLOBALTAGS
  1116. Name of the command used by the -t option to find global tags.
  1117. Normally should be set to "global" if your system has the global
  1118. (1) command. If not set, global tags are not used.
  1119. LESSHISTFILE
  1120. Name of the history file used to remember search commands and
  1121. shell commands between invocations of less. If set to "-" or
  1122. "/dev/null", a history file is not used. The default is
  1123. "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and
  1124. Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini"
  1125. on OS/2 systems.
  1126. LESSHISTSIZE
  1127. The maximum number of commands to save in the history file. The
  1128. default is 100.
  1129. LESSKEY
  1130. Name of the default lesskey(1) file.
  1131. LESSKEY_SYSTEM
  1132. Name of the default system-wide lesskey(1) file.
  1133. LESSMETACHARS
  1134. List of characters which are considered "metacharacters" by the
  1135. shell.
  1136. LESSMETAESCAPE
  1137. Prefix which less will add before each metacharacter in a com-
  1138. mand sent to the shell. If LESSMETAESCAPE is an empty string,
  1139. commands containing metacharacters will not be passed to the
  1140. shell.
  1141. LESSOPEN
  1142. Command line to invoke the (optional) input-preprocessor.
  1143. LESSSECURE
  1144. Runs less in "secure" mode. See discussion under SECURITY.
  1145. LESSSEPARATOR
  1146. String to be appended to a directory name in filename comple-
  1147. tion.
  1148. LESSUTFBINFMT
  1149. Format for displaying non-printable Unicode code points.
  1150. LESS_IS_MORE
  1151. Emulate the more (1) command.
  1152. LINES Sets the number of lines on the screen. Takes precedence over
  1153. the number of lines specified by the TERM variable. (But if you
  1154. have a windowing system which supports TIOCGWINSZ or WIOCGETD,
  1155. the window system's idea of the screen size takes precedence
  1156. over the LINES and COLUMNS environment variables.)
  1157. PATH User's search path (used to find a lesskey file on MS-DOS and
  1158. OS/2 systems).
  1159. SHELL The shell used to execute the ! command, as well as to expand
  1160. filenames.
  1161. TERM The type of terminal on which less is being run.
  1162. VISUAL The name of the editor (used for the v command). SEE ALSO
  1163. lesskey(1) COPYRIGHT
  1164. Copyright (C) 1984-2007 Mark Nudelman
  1165. less is part of the GNU project and is free software. You can redis-
  1166. tribute it and/or modify it under the terms of either (1) the GNU Gen-
  1167. eral Public License as published by the Free Software Foundation; or
  1168. (2) the Less License. See the file README in the less distribution for
  1169. more details regarding redistribution. You should have received a copy
  1170. of the GNU General Public License along with the source for less; see
  1171. the file COPYING. If not, write to the Free Software Foundation, 59
  1172. Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should also
  1173. have received a copy of the Less License; see the file LICENSE.
  1174. less is distributed in the hope that it will be useful, but WITHOUT ANY
  1175. WARRANTY; without even the implied warranty of MERCHANTABILITY or FIT-
  1176. NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  1177. more details. AUTHOR
  1178. Mark Nudelman <markn@greenwoodsoftware.com>
  1179. See http://www.greenwoodsoftware.com/less/bugs.html for the latest list
  1180. of known bugs in less.
  1181. Send bug reports or comments to the above address or to
  1182. bug-less@gnu.org.
  1183. For more information, see the less homepage at
  1184. http://www.greenwoodsoftware.com/less.
  1185. Version 418: 02 Jan 2008 LESS(1)
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