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    1 '\" t
    2 .TH LESS 1 "Version 562: 19 May 2020"
    3 .SH NAME
    4 less \- opposite of more
    5 .SH SYNOPSIS
    6 .B "less \-?"
    7 .br
    8 .B "less \-\-help"
    9 .br
   10 .B "less \-V"
   11 .br
   12 .B "less \-\-version"
   13 .br
   14 .B "less [\-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]"
   15 .br
   16 .B "     [\-b \fIspace\/\fP] [\-h \fIlines\/\fP] [\-j \fIline\/\fP] [\-k \fIkeyfile\/\fP]"
   17 .br
   18 .B "     [\-{oO} \fIlogfile\/\fP] [\-p \fIpattern\/\fP] [\-P \fIprompt\/\fP] [\-t \fItag\/\fP]"
   19 .br
   20 .B "     [\-T \fItagsfile\/\fP] [\-x \fItab\/\fP,...] [\-y \fIlines\/\fP] [\-[z] \fIlines\/\fP]"
   21 .br
   22 .B "     [\-# \fIshift\/\fP] [+[+]\fIcmd\/\fP] [\-\-] [\fIfilename\/\fP]..."
   23 .br
   24 (See the OPTIONS section for alternate option syntax with long option names.)
   25 .
   26 .SH DESCRIPTION
   27 .I Less
   28 is a program similar to
   29 .IR more (1),
   30 but which allows backward movement
   31 in the file as well as forward movement.
   32 Also,
   33 .I less
   34 does not have to read the entire input file before starting,
   35 so with large input files it starts up faster than text editors like
   36 .IR vi (1).
   37 .I Less
   38 uses termcap (or terminfo on some systems),
   39 so it can run on a variety of terminals.
   40 There is even limited support for hardcopy terminals.
   41 (On a hardcopy terminal, lines which should be printed at the top
   42 of the screen are prefixed with a caret.)
   43 .PP
   44 Commands are based on both
   45 .I more
   46 and
   47 .IR vi .
   48 Commands may be preceded by a decimal number,
   49 called N in the descriptions below.
   50 The number is used by some commands, as indicated.
   51 .
   52 .SH COMMANDS
   53 In the following descriptions, ^X means control-X.
   54 ESC stands for the ESCAPE key; for example ESC-v means the
   55 two character sequence "ESCAPE", then "v".
   56 .IP "h or H"
   57 Help: display a summary of these commands.
   58 If you forget all the other commands, remember this one.
   59 .IP "SPACE or ^V or f or ^F"
   60 Scroll forward N lines, default one window (see option \-z below).
   61 If N is more than the screen size, only the final screenful is displayed.
   62 Warning: some systems use ^V as a special literalization character.
   63 .IP "z"
   64 Like SPACE, but if N is specified, it becomes the new window size.
   65 .IP "ESC-SPACE"
   66 Like SPACE, but scrolls a full screenful, even if it reaches
   67 end-of-file in the process.
   68 .IP "ENTER or RETURN or ^N or e or ^E or j or ^J"
   69 Scroll forward N lines, default 1.
   70 The entire N lines are displayed, even if N is more than the screen size.
   71 .IP "d or ^D"
   72 Scroll forward N lines, default one half of the screen size.
   73 If N is specified, it becomes the new default for
   74 subsequent d and u commands.
   75 .IP "b or ^B or ESC-v"
   76 Scroll backward N lines, default one window (see option \-z below).
   77 If N is more than the screen size, only the final screenful is displayed.
   78 .IP "w"
   79 Like ESC-v, but if N is specified, it becomes the new window size.
   80 .IP "y or ^Y or ^P or k or ^K"
   81 Scroll backward N lines, default 1.
   82 The entire N lines are displayed, even if N is more than the screen size.
   83 Warning: some systems use ^Y as a special job control character.
   84 .IP "u or ^U"
   85 Scroll backward N lines, default one half of the screen size.
   86 If N is specified, it becomes the new default for
   87 subsequent d and u commands.
   88 .IP "J"
   89 Like j, but continues to scroll beyond the end of the file.
   90 .IP "K or Y"
   91 Like k, but continues to scroll beyond the beginning of the file.
   92 .IP "ESC-) or RIGHTARROW"
   93 Scroll horizontally right N characters, default half the screen width
   94 (see the \-# option).
   95 If a number N is specified, it becomes the default for future RIGHTARROW
   96 and LEFTARROW commands.
   97 While the text is scrolled, it acts as though the \-S option
   98 (chop lines) were in effect.
   99 .IP "ESC-( or LEFTARROW"
  100 Scroll horizontally left N characters, default half the screen width
  101 (see the \-# option).
  102 If a number N is specified, it becomes the default for future RIGHTARROW
  103 and LEFTARROW commands.
  104 .IP "ESC-} or ^RIGHTARROW"
  105 Scroll horizontally right to show the end of the longest displayed line.
  106 .IP "ESC-{ or ^LEFTARROW"
  107 Scroll horizontally left back to the first column.
  108 .IP "r or ^R or ^L"
  109 Repaint the screen.
  110 .IP R
  111 Repaint the screen, discarding any buffered input.
  112 Useful if the file is changing while it is being viewed.
  113 .IP "F"
  114 Scroll forward, and keep trying to read when the
  115 end of file is reached.
  116 Normally this command would be used when already at the end of the file.
  117 It is a way to monitor the tail of a file which is growing
  118 while it is being viewed.
  119 (The behavior is similar to the "tail \-f" command.)
  120 .IP "ESC-F"
  121 Like F, but as soon as a line is found which matches
  122 the last search pattern, the terminal bell is rung
  123 and forward scrolling stops.
  124 .IP "g or < or ESC-<"
  125 Go to line N in the file, default 1 (beginning of file).
  126 (Warning: this may be slow if N is large.)
  127 .IP "G or > or ESC->"
  128 Go to line N in the file, default the end of the file.
  129 (Warning: this may be slow if N is large,
  130 or if N is not specified and
  131 standard input, rather than a file, is being read.)
  132 .IP "ESC-G"
  133 Same as G, except if no number N is specified and the input is standard input,
  134 goes to the last line which is currently buffered.
  135 .IP "p or %"
  136 Go to a position N percent into the file.
  137 N should be between 0 and 100, and may contain a decimal point.
  138 .IP "P"
  139 Go to the line containing byte offset N in the file.
  140 .IP "{"
  141 If a left curly bracket appears in the top line displayed
  142 on the screen,
  143 the { command will go to the matching right curly bracket.
  144 The matching right curly bracket is positioned on the bottom
  145 line of the screen.
  146 If there is more than one left curly bracket on the top line,
  147 a number N may be used to specify the N-th bracket on the line.
  148 .IP "}"
  149 If a right curly bracket appears in the bottom line displayed
  150 on the screen,
  151 the } command will go to the matching left curly bracket.
  152 The matching left curly bracket is positioned on the top
  153 line of the screen.
  154 If there is more than one right curly bracket on the top line,
  155 a number N may be used to specify the N-th bracket on the line.
  156 .IP "("
  157 Like {, but applies to parentheses rather than curly brackets.
  158 .IP ")"
  159 Like }, but applies to parentheses rather than curly brackets.
  160 .IP "["
  161 Like {, but applies to square brackets rather than curly brackets.
  162 .IP "]"
  163 Like }, but applies to square brackets rather than curly brackets.
  164 .IP "ESC-^F"
  165 Followed by two characters,
  166 acts like {, but uses the two characters as open and close brackets,
  167 respectively.
  168 For example, "ESC ^F < >" could be used to
  169 go forward to the > which matches the < in the top displayed line.
  170 .IP "ESC-^B"
  171 Followed by two characters,
  172 acts like }, but uses the two characters as open and close brackets,
  173 respectively.
  174 For example, "ESC ^B < >" could be used to
  175 go backward to the < which matches the > in the bottom displayed line.
  176 .IP m
  177 Followed by any lowercase or uppercase letter,
  178 marks the first displayed line with that letter.
  179 If the status column is enabled via the \-J option,
  180 the status column shows the marked line.
  181 .IP M
  182 Acts like m, except the last displayed line is marked
  183 rather than the first displayed line.
  184 .IP "'"
  185 (Single quote.)
  186 Followed by any lowercase or uppercase letter, returns to the position which
  187 was previously marked with that letter.
  188 Followed by another single quote, returns to the position at
  189 which the last "large" movement command was executed.
  190 Followed by a ^ or $, jumps to the beginning or end of the
  191 file respectively.
  192 Marks are preserved when a new file is examined,
  193 so the ' command can be used to switch between input files.
  194 .IP "^X^X"
  195 Same as single quote.
  196 .IP "ESC-m"
  197 Followed by any lowercase or uppercase letter,
  198 clears the mark identified by that letter.
  199 .IP /pattern
  200 Search forward in the file for the N-th line containing the pattern.
  201 N defaults to 1.
  202 The pattern is a regular expression, as recognized by
  203 the regular expression library supplied by your system.
  204 The search starts at the first line displayed
  205 (but see the \-a and \-j options, which change this).
  206 .sp
  207 Certain characters are special
  208 if entered at the beginning of the pattern;
  209 they modify the type of search rather than become part of the pattern:
  210 .RS
  211 .IP "^N or !"
  212 Search for lines which do NOT match the pattern.
  213 .IP "^E or *"
  214 Search multiple files.
  215 That is, if the search reaches the END of the current file
  216 without finding a match,
  217 the search continues in the next file in the command line list.
  218 .IP "^F or @"
  219 Begin the search at the first line of the FIRST file
  220 in the command line list,
  221 regardless of what is currently displayed on the screen
  222 or the settings of the \-a or \-j options.
  223 .IP "^K"
  224 Highlight any text which matches the pattern on the current screen,
  225 but don't move to the first match (KEEP current position).
  226 .IP "^R"
  227 Don't interpret regular expression metacharacters;
  228 that is, do a simple textual comparison.
  229 .RE
  230 .IP ?pattern
  231 Search backward in the file for the N-th line containing the pattern.
  232 The search starts at the last line displayed
  233 (but see the \-a and \-j options, which change this).
  234 .sp
  235 Certain characters are special as in the / command:
  236 .RS
  237 .IP "^N or !"
  238 Search for lines which do NOT match the pattern.
  239 .IP "^E or *"
  240 Search multiple files.
  241 That is, if the search reaches the beginning of the current file
  242 without finding a match,
  243 the search continues in the previous file in the command line list.
  244 .IP "^F or @"
  245 Begin the search at the last line of the last file
  246 in the command line list,
  247 regardless of what is currently displayed on the screen
  248 or the settings of the \-a or \-j options.
  249 .IP "^K"
  250 As in forward searches.
  251 .IP "^R"
  252 As in forward searches.
  253 .RE
  254 .IP "ESC-/pattern"
  255 Same as "/*".
  256 .IP "ESC-?pattern"
  257 Same as "?*".
  258 .IP n
  259 Repeat previous search, for N-th line containing the last pattern.
  260 If the previous search was modified by ^N, the search is made for the
  261 N-th line NOT containing the pattern.
  262 If the previous search was modified by ^E, the search continues
  263 in the next (or previous) file if not satisfied in the current file.
  264 If the previous search was modified by ^R, the search is done
  265 without using regular expressions.
  266 There is no effect if the previous search was modified by ^F or ^K.
  267 .IP N
  268 Repeat previous search, but in the reverse direction.
  269 .IP "ESC-n"
  270 Repeat previous search, but crossing file boundaries.
  271 The effect is as if the previous search were modified by *.
  272 .IP "ESC-N"
  273 Repeat previous search, but in the reverse direction
  274 and crossing file boundaries.
  275 .IP "ESC-u"
  276 Undo search highlighting.
  277 Turn off highlighting of strings matching the current search pattern.
  278 If highlighting is already off because of a previous ESC-u command,
  279 turn highlighting back on.
  280 Any search command will also turn highlighting back on.
  281 (Highlighting can also be disabled by toggling the \-G option;
  282 in that case search commands do not turn highlighting back on.)
  283 .IP "&pattern"
  284 Display only lines which match the pattern;
  285 lines which do not match the pattern are not displayed.
  286 If pattern is empty (if you type & immediately followed by ENTER),
  287 any filtering is turned off, and all lines are displayed.
  288 While filtering is in effect, an ampersand is displayed at the
  289 beginning of the prompt,
  290 as a reminder that some lines in the file may be hidden.
  291 .sp
  292 Certain characters are special as in the / command:
  293 .RS
  294 .IP "^N or !"
  295 Display only lines which do NOT match the pattern.
  296 .IP "^R"
  297 Don't interpret regular expression metacharacters;
  298 that is, do a simple textual comparison.
  299 .RE
  300 .IP ":e [filename]"
  301 Examine a new file.
  302 If the filename is missing, the "current" file (see the :n and :p commands
  303 below) from the list of files in the command line is re-examined.
  304 A percent sign (%) in the filename is replaced by the name of the
  305 current file.
  306 A pound sign (#) is replaced by the name of the previously examined file.
  307 However, two consecutive percent signs are simply
  308 replaced with a single percent sign.
  309 This allows you to enter a filename that contains a percent sign
  310 in the name.
  311 Similarly, two consecutive pound signs are replaced with a single pound sign.
  312 The filename is inserted into the command line list of files
  313 so that it can be seen by subsequent :n and :p commands.
  314 If the filename consists of several files, they are all inserted into
  315 the list of files and the first one is examined.
  316 If the filename contains one or more spaces,
  317 the entire filename should be enclosed in double quotes
  318 (also see the \-" option).
  319 .IP "^X^V or E"
  320 Same as :e.
  321 Warning: some systems use ^V as a special literalization character.
  322 On such systems, you may not be able to use ^V.
  323 .IP ":n"
  324 Examine the next file (from the list of files given in the command line).
  325 If a number N is specified, the N-th next file is examined.
  326 .IP ":p"
  327 Examine the previous file in the command line list.
  328 If a number N is specified, the N-th previous file is examined.
  329 .IP ":x"
  330 Examine the first file in the command line list.
  331 If a number N is specified, the N-th file in the list is examined.
  332 .IP ":d"
  333 Remove the current file from the list of files.
  334 .IP "t"
  335 Go to the next tag, if there were more than one matches for the current tag.
  336 See the \-t option for more details about tags.
  337 .IP "T"
  338 Go to the previous tag, if there were more than one matches for the current tag.
  339 .IP "= or ^G or :f"
  340 Prints some information about the file being viewed,
  341 including its name
  342 and the line number and byte offset of the bottom line being displayed.
  343 If possible, it also prints the length of the file,
  344 the number of lines in the file
  345 and the percent of the file above the last displayed line.
  346 .IP \-
  347 Followed by one of the command line option letters (see OPTIONS below),
  348 this will change the setting of that option
  349 and print a message describing the new setting.
  350 If a ^P (CONTROL-P) is entered immediately after the dash,
  351 the setting of the option is changed but no message is printed.
  352 If the option letter has a numeric value (such as \-b or \-h),
  353 or a string value (such as \-P or \-t),
  354 a new value may be entered after the option letter.
  355 If no new value is entered, a message describing
  356 the current setting is printed and nothing is changed.
  357 .IP \-\-
  358 Like the \- command, but takes a long option name (see OPTIONS below)
  359 rather than a single option letter.
  360 You must press ENTER or RETURN after typing the option name.
  361 A ^P immediately after the second dash suppresses printing of a
  362 message describing the new setting, as in the \- command.
  363 .IP \-+
  364 Followed by one of the command line option letters
  365 this will reset the option to its default setting
  366 and print a message describing the new setting.
  367 (The "\-+\fIX\fP" command does the same thing
  368 as "\-+\fIX\fP" on the command line.)
  369 This does not work for string-valued options.
  370 .IP \-\-+
  371 Like the \-+ command, but takes a long option name
  372 rather than a single option letter.
  373 .IP \-!
  374 Followed by one of the command line option letters,
  375 this will reset the option to the "opposite" of its default setting
  376 and print a message describing the new setting.
  377 This does not work for numeric or string-valued options.
  378 .IP \-\-!
  379 Like the \-!\& command, but takes a long option name
  380 rather than a single option letter.
  381 .IP _
  382 (Underscore.)
  383 Followed by one of the command line option letters,
  384 this will print a message describing the current setting of that option.
  385 The setting of the option is not changed.
  386 .IP __
  387 (Double underscore.)
  388 Like the _ (underscore) command, but takes a long option name
  389 rather than a single option letter.
  390 You must press ENTER or RETURN after typing the option name.
  391 .IP +cmd
  392 Causes the specified cmd to be executed each time a new file is examined.
  393 For example, +G causes
  394 .I less
  395 to initially display each file starting at the end
  396 rather than the beginning.
  397 .IP V
  398 Prints the version number of
  399 .I less
  400 being run.
  401 .IP "q or Q or :q or :Q or ZZ"
  402 Exits
  403 .IR less .
  404 .PP
  405 The following
  406 four
  407 commands may or may not be valid, depending on your particular installation.
  408 .
  409 .IP v
  410 Invokes an editor to edit the current file being viewed.
  411 The editor is taken from the environment variable VISUAL if defined,
  412 or EDITOR if VISUAL is not defined,
  413 or defaults to "vi" if neither VISUAL nor EDITOR is defined.
  414 See also the discussion of LESSEDIT under the section on PROMPTS below.
  415 .IP "! shell-command"
  416 Invokes a shell to run the shell-command given.
  417 A percent sign (%) in the command is replaced by the name of the
  418 current file.
  419 A pound sign (#) is replaced by the name of the previously examined file.
  420 "!!" repeats the last shell command.
  421 "!" with no shell command simply invokes a shell.
  422 On Unix systems, the shell is taken from the environment variable SHELL,
  423 or defaults to "sh".
  424 On MS-DOS and OS/2 systems, the shell is the normal command processor.
  425 .IP "| <m> shell-command"
  426 <m> represents any mark letter.
  427 Pipes a section of the input file to the given shell command.
  428 The section of the file to be piped is between the position marked by
  429 the letter and the current screen.
  430 The entire current screen is included, regardless of whether the
  431 marked position is before or after the current screen.
  432 <m> may also be ^ or $ to indicate beginning or end of file respectively.
  433 If <m> is \&.\& or newline, the current screen is piped.
  434 .IP "s filename"
  435 Save the input to a file.
  436 This only works if the input is a pipe, not an ordinary file.
  437 .
  438 .SH OPTIONS
  439 Command line options are described below.
  440 Most options may be changed while
  441 .I less
  442 is running, via the "\-" command.
  443 .PP
  444 Most options may be given in one of two forms:
  445 either a dash followed by a single letter,
  446 or two dashes followed by a long option name.
  447 A long option name may be abbreviated as long as
  448 the abbreviation is unambiguous.
  449 For example, \-\-quit-at-eof may be abbreviated \-\-quit, but not
  450 \-\-qui, since both \-\-quit-at-eof and \-\-quiet begin with \-\-qui.
  451 Some long option names are in uppercase, such as \-\-QUIT-AT-EOF, as
  452 distinct from \-\-quit-at-eof.
  453 Such option names need only have their first letter capitalized;
  454 the remainder of the name may be in either case.
  455 For example, \-\-Quit-at-eof is equivalent to \-\-QUIT-AT-EOF.
  456 .PP
  457 Options are also taken from the environment variable "LESS".
  458 For example,
  459 to avoid typing "less \-options \&...\&" each time
  460 .I less
  461 is invoked, you might tell
  462 .IR csh :
  463 .sp
  464 setenv LESS "\-options"
  465 .sp
  466 or if you use
  467 .IR sh :
  468 .sp
  469 LESS="\-options"; export LESS
  470 .sp
  471 On MS-DOS, you don't need the quotes, but you should replace any
  472 percent signs in the options string by double percent signs.
  473 .sp
  474 The environment variable is parsed before the command line,
  475 so command line options override the LESS environment variable.
  476 If an option appears in the LESS variable, it can be reset
  477 to its default value on the command line by beginning the command
  478 line option with "\-+".
  479 .sp
  480 Some options like \-k or \-D require a string to follow the option letter.
  481 The string for that option is considered to end when a dollar sign ($) is found.
  482 For example, you can set two \-D options on MS-DOS like this:
  483 .sp
  484 LESS="Dn9.1$Ds4.1"
  485 .sp
  486 If the \-\-use-backslash option appears earlier in the options, then
  487 a dollar sign or backslash may be included literally in an option string
  488 by preceding it with a backslash.
  489 If the \-\-use-backslash option is not in effect, then backslashes are
  490 not treated specially, and there is no way to include a dollar sign
  491 in the option string.
  492 .IP "\-? or \-\-help"
  493 This option displays a summary of the commands accepted by
  494 .I less
  495 (the same as the h command).
  496 (Depending on how your shell interprets the question mark,
  497 it may be necessary to quote the question mark, thus: "\-\e?".)
  498 .IP "\-a or \-\-search-skip-screen"
  499 By default, forward searches start at the top of the displayed screen
  500 and backwards searches start at the bottom of the displayed screen
  501 (except for repeated searches invoked by the n or N commands,
  502 which start after or before the "target" line respectively;
  503 see the \-j option for more about the target line).
  504 The \-a option causes forward searches to instead start at
  505 the bottom of the screen
  506 and backward searches to start at the top of the screen,
  507 thus skipping all lines displayed on the screen.
  508 .IP "\-A or \-\-SEARCH-SKIP-SCREEN"
  509 Causes all forward searches (not just non-repeated searches)
  510 to start just after the target line, and all backward searches
  511 to start just before the target line.
  512 Thus, forward searches will skip part of the displayed screen
  513 (from the first line up to and including the target line).
  514 Similarly backwards searches will skip the displayed screen
  515 from the last line up to and including the target line.
  516 This was the default behavior in less versions prior to 441.
  517 .IP "\-b\fIn\fP or \-\-buffers=\fIn\fP"
  518 Specifies the amount of buffer space
  519 .I less
  520 will use for each file, in units of kilobytes (1024 bytes).
  521 By default 64\ KB of buffer space is used for each file
  522 (unless the file is a pipe; see the \-B option).
  523 The \-b option specifies instead that \fIn\fP kilobytes of
  524 buffer space should be used for each file.
  525 If \fIn\fP is \-1, buffer space is unlimited; that is,
  526 the entire file can be read into memory.
  527 .IP "\-B or \-\-auto-buffers"
  528 By default, when data is read from a pipe,
  529 buffers are allocated automatically as needed.
  530 If a large amount of data is read from the pipe, this can cause
  531 a large amount of memory to be allocated.
  532 The \-B option disables this automatic allocation of buffers for pipes,
  533 so that only 64\ KB
  534 (or the amount of space specified by the \-b option)
  535 is used for the pipe.
  536 Warning: use of \-B can result in erroneous display, since only the
  537 most recently viewed part of the piped data is kept in memory;
  538 any earlier data is lost.
  539 .IP "\-c or \-\-clear-screen"
  540 Causes full screen repaints to be painted from the top line down.
  541 By default,
  542 full screen repaints are done by scrolling from the bottom of the screen.
  543 .IP "\-C or \-\-CLEAR-SCREEN"
  544 Same as \-c, for compatibility with older versions of
  545 .IR less .
  546 .IP "\-d or \-\-dumb"
  547 The \-d option suppresses the error message
  548 normally displayed if the terminal is dumb;
  549 that is, lacks some important capability,
  550 such as the ability to clear the screen or scroll backward.
  551 The \-d option does not otherwise change the behavior of
  552 .I less
  553 on a dumb terminal.
  554 .IP "\-D\fBx\fP\fIcolor\fP or \-\-color=\fBx\fP\fIcolor\fP"
  555 [MS-DOS only]
  556 Sets the color of the text displayed.
  557 \fBx\fP is a single character which selects the type of text whose color is
  558 being set: n=normal, s=standout, d=bold, u=underlined, k=blink.
  559 \fIcolor\fP is a pair of numbers separated by a period.
  560 The first number selects the foreground color and the second selects
  561 the background color of the text.
  562 A single number \fIN\fP is the same as \fIN.M\fP,
  563 where \fIM\fP is the normal background color.
  564 The color may start or end with \fBu\fP to use underline (with the normal
  565 color, if by itself), if the system supports it (Windows only).
  566 \fBx\fP may also be \fBa\fP to toggle strict ANSI sequence rendering
  567 (SGR mode).
  568 .
  569 .IP "\-e or \-\-quit-at-eof"
  570 Causes
  571 .I less
  572 to automatically exit
  573 the second time it reaches end-of-file.
  574 By default, the only way to exit
  575 .I less
  576 is via the "q" command.
  577 .IP "\-E or \-\-QUIT-AT-EOF"
  578 Causes
  579 .I less
  580 to automatically exit the first time it reaches end-of-file.
  581 .IP "\-f or \-\-force"
  582 Forces non-regular files to be opened.
  583 (A non-regular file is a directory or a device special file.)
  584 Also suppresses the warning message when a binary file is opened.
  585 By default,
  586 .I less
  587 will refuse to open non-regular files.
  588 Note that some operating systems will not allow directories
  589 to be read, even if \-f is set.
  590 .IP "\-F or \-\-quit-if-one-screen"
  591 Causes
  592 .I less
  593 to automatically exit
  594 if the entire file can be displayed on the first screen.
  595 .IP "\-g or \-\-hilite-search"
  596 Normally,
  597 .I less
  598 will highlight ALL strings which match the last search command.
  599 The \-g option changes this behavior to highlight only the particular string
  600 which was found by the last search command.
  601 This can cause
  602 .I less
  603 to run somewhat faster than the default.
  604 .IP "\-G or \-\-HILITE-SEARCH"
  605 The \-G option suppresses all highlighting of strings found by search commands.
  606 .IP "\-h\fIn\fP or \-\-max-back-scroll=\fIn\fP"
  607 Specifies a maximum number of lines to scroll backward.
  608 If it is necessary to scroll backward more than \fIn\fP lines,
  609 the screen is repainted in a forward direction instead.
  610 (If the terminal does not have the ability to scroll
  611 backward, \-h0 is implied.)
  612 .IP "\-i or \-\-ignore-case"
  613 Causes searches to ignore case; that is,
  614 uppercase and lowercase are considered identical.
  615 This option is ignored if any uppercase letters
  616 appear in the search pattern;
  617 in other words,
  618 if a pattern contains uppercase letters, then that search does not ignore case.
  619 .IP "\-I or \-\-IGNORE-CASE"
  620 Like \-i, but searches ignore case even if
  621 the pattern contains uppercase letters.
  622 .IP "\-j\fIn\fP or \-\-jump-target=\fIn\fP"
  623 Specifies a line on the screen where the "target" line
  624 is to be positioned.
  625 The target line is the line specified by any command to
  626 search for a pattern, jump to a line number,
  627 jump to a file percentage or jump to a tag.
  628 The screen line may be specified by a number: the top line on the screen
  629 is 1, the next is 2, and so on.
  630 The number may be negative to specify a line relative to the bottom
  631 of the screen: the bottom line on the screen is \-1, the second
  632 to the bottom is \-2, and so on.
  633 Alternately, the screen line may be specified as a fraction of the height
  634 of the screen, starting with a decimal point: \&.5 is in the middle of the
  635 screen, \&.3 is three tenths down from the first line, and so on.
  636 If the line is specified as a fraction, the actual line number
  637 is recalculated if the terminal window is resized, so that the
  638 target line remains at the specified fraction of the screen height.
  639 If any form of the \-j option is used,
  640 repeated forward searches (invoked with "n" or "N")
  641 begin at the line immediately after the target line,
  642 and repeated backward searches begin at the target line,
  643 unless changed by \-a or \-A.
  644 For example, if "\-j4" is used, the target line is the
  645 fourth line on the screen, so forward searches begin at the fifth line
  646 on the screen.
  647 However nonrepeated searches (invoked with "/" or "?")
  648 always begin at the start or end of the current screen respectively.
  649 .IP "\-J or \-\-status-column"
  650 Displays a status column at the left edge of the screen.
  651 The status column shows the lines that matched the current search,
  652 and any lines that are marked (via the m or M command).
  653 The status column is also used if the \-w or \-W option is in effect.
  654 .IP "\-k\fIfilename\fP or \-\-lesskey-file=\fIfilename\fP"
  655 Causes
  656 .I less
  657 to open and interpret the named file as a
  658 .IR lesskey (1)
  659 file.
  660 Multiple \-k options may be specified.
  661 If the LESSKEY or LESSKEY_SYSTEM environment variable is set, or
  662 if a lesskey file is found in a standard place (see KEY BINDINGS),
  663 it is also used as a
  664 .I lesskey
  665 file.
  666 .IP "\-K or \-\-quit-on-intr"
  667 Causes
  668 .I less
  669 to exit immediately (with status 2)
  670 when an interrupt character (usually ^C) is typed.
  671 Normally, an interrupt character causes
  672 .I less
  673 to stop whatever it is doing and return to its command prompt.
  674 Note that use of this option makes it impossible to return to the
  675 command prompt from the "F" command.
  676 .IP "\-L or \-\-no-lessopen"
  677 Ignore the LESSOPEN environment variable
  678 (see the INPUT PREPROCESSOR section below).
  679 This option can be set from within \fIless\fP,
  680 but it will apply only to files opened subsequently, not to the
  681 file which is currently open.
  682 .IP "\-m or \-\-long-prompt"
  683 Causes
  684 .I less
  685 to prompt verbosely (like \fImore\fP),
  686 with the percent into the file.
  687 By default,
  688 .I less
  689 prompts with a colon.
  690 .IP "\-M or \-\-LONG-PROMPT"
  691 Causes
  692 .I less
  693 to prompt even more verbosely than
  694 .IR more .
  695 .IP "\-n or \-\-line-numbers"
  696 Suppresses line numbers.
  697 The default (to use line numbers) may cause
  698 .I less
  699 to run more slowly in some cases, especially with a very large input file.
  700 Suppressing line numbers with the \-n option will avoid this problem.
  701 Using line numbers means: the line number will be displayed in the verbose
  702 prompt and in the = command,
  703 and the v command will pass the current line number to the editor
  704 (see also the discussion of LESSEDIT in PROMPTS below).
  705 .IP "\-N or \-\-LINE-NUMBERS"
  706 Causes a line number to be displayed at the beginning of
  707 each line in the display.
  708 .IP "\-o\fIfilename\fP or \-\-log-file=\fIfilename\fP"
  709 Causes
  710 .I less
  711 to copy its input to the named file as it is being viewed.
  712 This applies only when the input file is a pipe,
  713 not an ordinary file.
  714 If the file already exists,
  715 .I less
  716 will ask for confirmation before overwriting it.
  717 .IP "\-O\fIfilename\fP or \-\-LOG-FILE=\fIfilename\fP"
  718 The \-O option is like \-o, but it will overwrite an existing
  719 file without asking for confirmation.
  720 .sp
  721 If no log file has been specified,
  722 the \-o and \-O options can be used from within
  723 .I less
  724 to specify a log file.
  725 Without a file name, they will simply report the name of the log file.
  726 The "s" command is equivalent to specifying \-o from within
  727 .IR less .
  728 .IP "\-p\fIpattern\fP or \-\-pattern=\fIpattern\fP"
  729 The \-p option on the command line is equivalent to
  730 specifying +/\fIpattern\fP;
  731 that is, it tells
  732 .I less
  733 to start at the first occurrence of \fIpattern\fP in the file.
  734 .IP "\-P\fIprompt\fP or \-\-prompt=\fIprompt\fP"
  735 Provides a way to tailor the three prompt
  736 styles to your own preference.
  737 This option would normally be put in the LESS environment
  738 variable, rather than being typed in with each
  739 .I less
  740 command.
  741 Such an option must either be the last option in the LESS variable,
  742 or be terminated by a dollar sign.
  743  \-Ps followed by a string changes the default (short) prompt
  744 to that string.
  745  \-Pm changes the medium (\-m) prompt.
  746  \-PM changes the long (\-M) prompt.
  747  \-Ph changes the prompt for the help screen.
  748  \-P= changes the message printed by the = command.
  749  \-Pw changes the message printed while waiting for data (in the F command).
  750 .sp 1
  751 All prompt strings consist of a sequence of
  752 letters and special escape sequences.
  753 See the section on PROMPTS for more details.
  754 .IP "\-q or \-\-quiet or \-\-silent"
  755 Causes moderately "quiet" operation:
  756 the terminal bell is not rung
  757 if an attempt is made to scroll past the end of the file
  758 or before the beginning of the file.
  759 If the terminal has a "visual bell", it is used instead.
  760 The bell will be rung on certain other errors,
  761 such as typing an invalid character.
  762 The default is to ring the terminal bell in all such cases.
  763 .IP "\-Q or \-\-QUIET or \-\-SILENT"
  764 Causes totally "quiet" operation:
  765 the terminal bell is never rung.
  766 If the terminal has a "visual bell", it is used in all cases
  767 where the terminal bell would have been rung.
  768 .IP "\-r or \-\-raw-control-chars"
  769 Causes "raw" control characters to be displayed.
  770 The default is to display control characters using the caret notation;
  771 for example, a control-A (octal 001) is displayed as "^A".
  772 Warning: when the \-r option is used,
  773 .I less
  774 cannot keep track of the actual appearance of the screen
  775 (since this depends on how the screen responds to
  776 each type of control character).
  777 Thus, various display problems may result,
  778 such as long lines being split in the wrong place.
  779 .IP "\-R or \-\-RAW-CONTROL-CHARS"
  780 Like \-r, but only ANSI "color" escape sequences are output in "raw" form.
  781 Unlike \-r, the screen appearance is maintained correctly in most cases.
  782 ANSI "color" escape sequences are sequences of the form:
  783 .sp
  784 	ESC [ \&...\& m
  785 .sp
  786 where the "...\&" is zero or more color specification characters
  787 For the purpose of keeping track of screen appearance,
  788 ANSI color escape sequences are assumed to not move the cursor.
  789 You can make
  790 .I less
  791 think that characters other than "m" can end ANSI color escape sequences
  792 by setting the environment variable LESSANSIENDCHARS to the list of
  793 characters which can end a color escape sequence.
  794 And you can make
  795 .I less
  796 think that characters other than the standard ones may appear between
  797 the ESC and the m by setting the environment variable LESSANSIMIDCHARS
  798 to the list of characters which can appear.
  799 .IP "\-s or \-\-squeeze-blank-lines"
  800 Causes consecutive blank lines to be squeezed into a single blank line.
  801 This is useful when viewing
  802 .I nroff
  803 output.
  804 .IP "\-S or \-\-chop-long-lines"
  805 Causes lines longer than the screen width to be
  806 chopped (truncated) rather than wrapped.
  807 That is, the portion of a long line that does not fit in
  808 the screen width is not displayed until you press RIGHT-ARROW.
  809 The default is to wrap long lines; that is, display the remainder
  810 on the next line.
  811 .IP "\-t\fItag\fP or \-\-tag=\fItag\fP"
  812 The \-t option, followed immediately by a TAG,
  813 will edit the file containing that tag.
  814 For this to work, tag information must be available;
  815 for example, there may be a file in the current directory called "tags",
  816 which was previously built by
  817 .IR ctags (1)
  818 or an equivalent command.
  819 If the environment variable LESSGLOBALTAGS is set, it is taken to be
  820 the name of a command compatible with
  821 .IR global (1),
  822 and that command is executed to find the tag.
  823 (See http://www.gnu.org/software/global/global.html).
  824 The \-t option may also be specified from within
  825 .I less
  826 (using the \- command) as a way of examining a new file.
  827 The command ":t" is equivalent to specifying \-t from within
  828 .IR less .
  829 .IP "\-T\fItagsfile\fP or \-\-tag-file=\fItagsfile\fP"
  830 Specifies a tags file to be used instead of "tags".
  831 .IP "\-u or \-\-underline-special"
  832 Causes backspaces and carriage returns to be treated as printable characters;
  833 that is, they are sent to the terminal when they appear in the input.
  834 .IP "\-U or \-\-UNDERLINE-SPECIAL"
  835 Causes backspaces, tabs, carriage returns and "formatting characters"
  836 (as defined by Unicode) to be treated as control characters;
  837 that is, they are handled as specified by the \-r option.
  838 .sp
  839 By default, if neither \-u nor \-U is given,
  840 backspaces which appear adjacent to an underscore character
  841 are treated specially:
  842 the underlined text is displayed
  843 using the terminal's hardware underlining capability.
  844 Also, backspaces which appear between two identical characters
  845 are treated specially:
  846 the overstruck text is printed
  847 using the terminal's hardware boldface capability.
  848 Other backspaces are deleted, along with the preceding character.
  849 Carriage returns immediately followed by a newline are deleted.
  850 Other carriage returns are handled as specified by the \-r option.
  851 Text which is overstruck or underlined can be searched for
  852 if neither \-u nor \-U is in effect.
  853 .IP "\-V or \-\-version"
  854 Displays the version number of
  855 .IR less .
  856 .IP "\-w or \-\-hilite-unread"
  857 Temporarily highlights the first "new" line after a forward movement
  858 of a full page.
  859 The first "new" line is the line immediately following the line previously
  860 at the bottom of the screen.
  861 Also highlights the target line after a g or p command.
  862 The highlight is removed at the next command which causes movement.
  863 The entire line is highlighted, unless the \-J option is in effect,
  864 in which case only the status column is highlighted.
  865 .IP "\-W or \-\-HILITE-UNREAD"
  866 Like \-w, but temporarily highlights the first new line after any
  867 forward movement command larger than one line.
  868 .IP "\-x\fIn\fP,...\& or \-\-tabs=\fIn\fP,..."
  869 Sets tab stops.
  870 If only one \fIn\fP is specified, tab stops are set at multiples of \fIn\fP.
  871 If multiple values separated by commas are specified, tab stops
  872 are set at those positions, and then continue with the same spacing as the
  873 last two.
  874 For example, \fI\-x9,17\fP will set tabs at positions 9, 17, 25, 33, etc.
  875 The default for \fIn\fP is 8.
  876 .IP "\-X or \-\-no-init"
  877 Disables sending the termcap initialization and deinitialization strings
  878 to the terminal.
  879 This is sometimes desirable if the deinitialization string does
  880 something unnecessary, like clearing the screen.
  881 .IP "\-y\fIn\fP or \-\-max-forw-scroll=\fIn\fP"
  882 Specifies a maximum number of lines to scroll forward.
  883 If it is necessary to scroll forward more than \fIn\fP lines,
  884 the screen is repainted instead.
  885 The \-c or \-C option may be used to repaint from the top of
  886 the screen if desired.
  887 By default, any forward movement causes scrolling.
  888 .IP "\-z\fIn\fP or \-\-window=\fIn\fP or \-\fIn\fP"
  889 Changes the default scrolling window size to \fIn\fP lines.
  890 The default is one screenful.
  891 The z and w commands can also be used to change the window size.
  892 The "z" may be omitted for compatibility with some versions of
  893 .IR more .
  894 If the number
  895 .I n
  896 is negative, it indicates
  897 .I n
  898 lines less than the current screen size.
  899 For example, if the screen is 24 lines, \fI\-z\-4\fP sets the
  900 scrolling window to 20 lines.  If the screen is resized to 40 lines,
  901 the scrolling window automatically changes to 36 lines.
  902 .IP "\-\(dq\fIcc\fP\ or\ \-\-quotes=\fIcc\fP"
  903 Changes the filename quoting character.
  904 This may be necessary if you are trying to name a file
  905 which contains both spaces and quote characters.
  906 Followed by a single character, this changes the quote character to that
  907 character.
  908 Filenames containing a space should then be surrounded by that character
  909 rather than by double quotes.
  910 Followed by two characters, changes the open quote to the first character,
  911 and the close quote to the second character.
  912 Filenames containing a space should then be preceded by the open quote
  913 character and followed by the close quote character.
  914 Note that even after the quote characters are changed, this option
  915 remains \-" (a dash followed by a double quote).
  916 .IP "\-~ or \-\-tilde"
  917 Normally lines after end of file are displayed as a single tilde (~).
  918 This option causes lines after end of file to be displayed as blank lines.
  919 .IP "\-# or \-\-shift"
  920 Specifies the default number of positions to scroll horizontally
  921 in the RIGHTARROW and LEFTARROW commands.
  922 If the number specified is zero, it sets the default number of
  923 positions to one half of the screen width.
  924 Alternately, the number may be specified as a fraction of the width
  925 of the screen, starting with a decimal point: \&.5 is half of the
  926 screen width, \&.3 is three tenths of the screen width, and so on.
  927 If the number is specified as a fraction, the actual number of
  928 scroll positions is recalculated if the terminal window is resized,
  929 so that the actual scroll remains at the specified fraction
  930 of the screen width.
  931 .IP "\-\-follow-name"
  932 Normally, if the input file is renamed while an F command is executing,
  933 .I less
  934 will continue to display the contents of the original file despite
  935 its name change.
  936 If \-\-follow-name is specified, during an F command
  937 .I less
  938 will periodically attempt to reopen the file by name.
  939 If the reopen succeeds and the file is a different file from the original
  940 (which means that a new file has been created
  941 with the same name as the original (now renamed) file),
  942 .I less
  943 will display the contents of that new file.
  944 .IP "\-\-mouse"
  945 Enables mouse input:
  946 scrolling the mouse wheel down moves forward in the file,
  947 scrolling the mouse wheel up moves backwards in the file,
  948 and clicking the mouse sets the "#" mark to the line
  949 where the mouse is clicked.
  950 The number of lines to scroll when the wheel is moved
  951 can be set by the \-\-wheel-lines option.
  952 Mouse input works only on terminals which support X11 mouse reporting,
  953 and on the Windows version of
  954 .IR less .
  955 .IP "\-\-MOUSE"
  956 Like \-\-mouse, except the direction scrolled
  957 on mouse wheel movement is reversed.
  958 .IP "\-\-no-keypad"
  959 Disables sending the keypad initialization and deinitialization strings
  960 to the terminal.
  961 This is sometimes useful if the keypad strings make the numeric
  962 keypad behave in an undesirable manner.
  963 .IP "\-\-no-histdups"
  964 This option changes the behavior so that if a search string or
  965 file name is typed in, and the same string is already in the history list,
  966 the existing copy is removed from the history list before the new one is added.
  967 Thus, a given string will appear only once in the history list.
  968 Normally, a string may appear multiple times.
  969 .IP "\-\-rscroll"
  970 This option changes the character used to mark truncated lines.
  971 It may begin with a two-character attribute indicator like LESSBINFMT does.
  972 If there is no attribute indicator, standout is used.
  973 If set to "\-", truncated lines are not marked.
  974 .IP "\-\-save-marks"
  975 Save marks in the history file, so marks are retained
  976 across different invocations of \fIless\fP.
  977 .IP "\-\-use-backslash"
  978 This option changes the interpretations of options which follow this one.
  979 After the \-\-use-backslash option, any backslash in an option string is
  980 removed and the following character is taken literally.
  981 This allows a dollar sign to be included in option strings.
  982 .IP "\-\-wheel-lines=\fIn\fP"
  983 Set the number of lines to scroll when the mouse wheel is scrolled
  984 and the \-\-mouse or \-\-MOUSE option is in effect.
  985 The default is 1 line.
  986 .IP \-\-
  987 A command line argument of "\-\-" marks the end of option arguments.
  988 Any arguments following this are interpreted as filenames.
  989 This can be useful when viewing a file whose name begins with a "\-" or "+".
  990 .IP +
  991 If a command line option begins with \fB+\fP,
  992 the remainder of that option is taken to be an initial command to
  993 .IR less .
  994 For example, +G tells
  995 .I less
  996 to start at the end of the file rather than the beginning,
  997 and +/xyz tells it to start at the first occurrence of "xyz" in the file.
  998 As a special case, +<number> acts like +<number>g;
  999 that is, it starts the display at the specified line number
 1000 (however, see the caveat under the "g" command above).
 1001 If the option starts with ++, the initial command applies to
 1002 every file being viewed, not just the first one.
 1003 The + command described previously
 1004 may also be used to set (or change) an initial command for every file.
 1005 .
 1006 .SH "LINE EDITING"
 1007 When entering command line at the bottom of the screen
 1008 (for example, a filename for the :e command,
 1009 or the pattern for a search command),
 1010 certain keys can be used to manipulate the command line.
 1011 Most commands have an alternate form in [ brackets ] which can be used if
 1012 a key does not exist on a particular keyboard.
 1013 (Note that the forms beginning with ESC do not work
 1014 in some MS-DOS and Windows systems because ESC is the line erase character.)
 1015 Any of these special keys may be entered literally by preceding
 1016 it with the "literal" character, either ^V or ^A.
 1017 A backslash itself may also be entered literally by entering two backslashes.
 1018 .IP "LEFTARROW [ ESC-h ]"
 1019 Move the cursor one space to the left.
 1020 .IP "RIGHTARROW [ ESC-l ]"
 1021 Move the cursor one space to the right.
 1022 .IP "^LEFTARROW [ ESC-b or ESC-LEFTARROW ]"
 1023 (That is, CONTROL and LEFTARROW simultaneously.)
 1024 Move the cursor one word to the left.
 1025 .IP "^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]"
 1026 (That is, CONTROL and RIGHTARROW simultaneously.)
 1027 Move the cursor one word to the right.
 1028 .IP "HOME [ ESC-0 ]"
 1029 Move the cursor to the beginning of the line.
 1030 .IP "END [ ESC-$ ]"
 1031 Move the cursor to the end of the line.
 1032 .IP "BACKSPACE"
 1033 Delete the character to the left of the cursor,
 1034 or cancel the command if the command line is empty.
 1035 .IP "DELETE or [ ESC-x ]"
 1036 Delete the character under the cursor.
 1037 .IP "^BACKSPACE [ ESC-BACKSPACE ]"
 1038 (That is, CONTROL and BACKSPACE simultaneously.)
 1039 Delete the word to the left of the cursor.
 1040 .IP "^DELETE [ ESC-X or ESC-DELETE ]"
 1041 (That is, CONTROL and DELETE simultaneously.)
 1042 Delete the word under the cursor.
 1043 .IP "UPARROW [ ESC-k ]"
 1044 Retrieve the previous command line.
 1045 If you first enter some text and then press UPARROW,
 1046 it will retrieve the previous command which begins with that text.
 1047 .IP "DOWNARROW [ ESC-j ]"
 1048 Retrieve the next command line.
 1049 If you first enter some text and then press DOWNARROW,
 1050 it will retrieve the next command which begins with that text.
 1051 .IP "TAB"
 1052 Complete the partial filename to the left of the cursor.
 1053 If it matches more than one filename, the first match
 1054 is entered into the command line.
 1055 Repeated TABs will cycle thru the other matching filenames.
 1056 If the completed filename is a directory, a "/" is appended to the filename.
 1057 (On MS-DOS systems, a "\e" is appended.)
 1058 The environment variable LESSSEPARATOR can be used to specify a
 1059 different character to append to a directory name.
 1060 .IP "BACKTAB [ ESC-TAB ]"
 1061 Like, TAB, but cycles in the reverse direction thru the matching filenames.
 1062 .IP "^L"
 1063 Complete the partial filename to the left of the cursor.
 1064 If it matches more than one filename, all matches are entered into
 1065 the command line (if they fit).
 1066 .IP "^U (Unix and OS/2) or ESC (MS-DOS)"
 1067 Delete the entire command line,
 1068 or cancel the command if the command line is empty.
 1069 If you have changed your line-kill character in Unix to something
 1070 other than ^U, that character is used instead of ^U.
 1071 .IP "^G"
 1072 Delete the entire command line and return to the main prompt.
 1073 .
 1074 .SH "KEY BINDINGS"
 1075 You may define your own
 1076 .I less
 1077 commands by using the program
 1078 .IR lesskey (1)
 1079 to create a lesskey file.
 1080 This file specifies a set of command keys and an action
 1081 associated with each key.
 1082 You may also use
 1083 .I lesskey
 1084 to change the line-editing keys (see LINE EDITING),
 1085 and to set environment variables.
 1086 If the environment variable LESSKEY is set,
 1087 .I less
 1088 uses that as the name of the lesskey file.
 1089 Otherwise,
 1090 .I less
 1091 looks in a standard place for the lesskey file:
 1092 On Unix systems,
 1093 .I less
 1094 looks for a lesskey file called "$HOME/.less".
 1095 On MS-DOS and Windows systems,
 1096 .I less
 1097 looks for a lesskey file called "$HOME/_less", and if it is not found there,
 1098 then looks for a lesskey file called "_less" in any directory specified
 1099 in the PATH environment variable.
 1100 On OS/2 systems,
 1101 .I less
 1102 looks for a lesskey file called "$HOME/less.ini", and if it is not found,
 1103 then looks for a lesskey file called "less.ini" in any directory specified
 1104 in the INIT environment variable, and if it not found there,
 1105 then looks for a lesskey file called "less.ini" in any directory specified
 1106 in the PATH environment variable.
 1107 See the
 1108 .I lesskey
 1109 manual page for more details.
 1110 .P
 1111 A system-wide lesskey file may also be set up to provide key bindings.
 1112 If a key is defined in both a local lesskey file and in the
 1113 system-wide file, key bindings in the local file take precedence over
 1114 those in the system-wide file.
 1115 If the environment variable LESSKEY_SYSTEM is set,
 1116 .I less
 1117 uses that as the name of the system-wide lesskey file.
 1118 Otherwise,
 1119 .I less
 1120 looks in a standard place for the system-wide lesskey file:
 1121 On Unix systems, the system-wide lesskey file is /usr/local/etc/sysless.
 1122 (However, if
 1123 .I less
 1124 was built with a different sysconf directory than /usr/local/etc,
 1125 that directory is where the sysless file is found.)
 1126 On MS-DOS and Windows systems, the system-wide lesskey file is c:\e_sysless.
 1127 On OS/2 systems, the system-wide lesskey file is c:\esysless.ini.
 1128 .
 1129 .SH "INPUT PREPROCESSOR"
 1130 You may define an "input preprocessor" for
 1131 .IR less .
 1132 Before
 1133 .I less
 1134 opens a file, it first gives your input preprocessor a chance to modify the
 1135 way the contents of the file are displayed.
 1136 An input preprocessor is simply an executable program (or shell script),
 1137 which writes the contents of the file to a different file,
 1138 called the replacement file.
 1139 The contents of the replacement file are then displayed
 1140 in place of the contents of the original file.
 1141 However, it will appear to the user as if the original file is opened;
 1142 that is,
 1143 .I less
 1144 will display the original filename as the name of the current file.
 1145 .PP
 1146 An input preprocessor receives one command line argument, the original filename,
 1147 as entered by the user.
 1148 It should create the replacement file, and when finished,
 1149 print the name of the replacement file to its standard output.
 1150 If the input preprocessor does not output a replacement filename,
 1151 .I less
 1152 uses the original file, as normal.
 1153 The input preprocessor is not called when viewing standard input.
 1154 To set up an input preprocessor, set the LESSOPEN environment variable
 1155 to a command line which will invoke your input preprocessor.
 1156 This command line should include one occurrence of the string "%s",
 1157 which will be replaced by the filename
 1158 when the input preprocessor command is invoked.
 1159 .PP
 1160 When
 1161 .I less
 1162 closes a file opened in such a way, it will call another program,
 1163 called the input postprocessor,
 1164 which may perform any desired clean-up action (such as deleting the
 1165 replacement file created by LESSOPEN).
 1166 This program receives two command line arguments, the original filename
 1167 as entered by the user, and the name of the replacement file.
 1168 To set up an input postprocessor, set the LESSCLOSE environment variable
 1169 to a command line which will invoke your input postprocessor.
 1170 It may include two occurrences of the string "%s";
 1171 the first is replaced with the original name of the file and
 1172 the second with the name of the replacement file,
 1173 which was output by LESSOPEN.
 1174 .PP
 1175 For example, on many Unix systems, these two scripts will allow you
 1176 to keep files in compressed format, but still let
 1177 .I less
 1178 view them directly:
 1179 .PP
 1180 lessopen.sh:
 1181 .br
 1182 	#! /bin/sh
 1183 .br
 1184 	case "$1" in
 1185 .br
 1186 	*.Z)	TEMPFILE=$(mktemp)
 1187 .br
 1188 		uncompress \-c $1  >$TEMPFILE  2>/dev/null
 1189 .br
 1190 		if [ \-s $TEMPFILE ]; then
 1191 .br
 1192 			echo $TEMPFILE
 1193 .br
 1194 		else
 1195 .br
 1196 			rm \-f $TEMPFILE
 1197 .br
 1198 		fi
 1199 .br
 1200 		;;
 1201 .br
 1202 	esac
 1203 .PP
 1204 lessclose.sh:
 1205 .br
 1206 	#! /bin/sh
 1207 .br
 1208 	rm $2
 1209 .PP
 1210 To use these scripts, put them both where they can be executed and
 1211 set LESSOPEN="lessopen.sh\ %s", and
 1212 LESSCLOSE="lessclose.sh\ %s\ %s".
 1213 More complex LESSOPEN and LESSCLOSE scripts may be written
 1214 to accept other types of compressed files, and so on.
 1215 .PP
 1216 It is also possible to set up an input preprocessor to
 1217 pipe the file data directly to
 1218 .IR less ,
 1219 rather than putting the data into a replacement file.
 1220 This avoids the need to decompress the entire file before
 1221 starting to view it.
 1222 An input preprocessor that works this way is called an input pipe.
 1223 An input pipe, instead of writing the name of a replacement file on
 1224 its standard output,
 1225 writes the entire contents of the replacement file on its standard output.
 1226 If the input pipe does not write any characters on its standard output,
 1227 then there is no replacement file and
 1228 .I less
 1229 uses the original file, as normal.
 1230 To use an input pipe,
 1231 make the first character in the LESSOPEN environment variable a
 1232 vertical bar (|) to signify that the input preprocessor is an input pipe.
 1233 As with non-pipe input preprocessors, the command string must contain one
 1234 occurrence of %s, which is replaced with the filename of the input file.
 1235 .PP
 1236 For example, on many Unix systems, this script will work like the
 1237 previous example scripts:
 1238 .PP
 1239 lesspipe.sh:
 1240 .br
 1241 	#! /bin/sh
 1242 .br
 1243 	case "$1" in
 1244 .br
 1245 	*.Z)	uncompress \-c $1  2>/dev/null
 1246 .br
 1247 		;;
 1248 .br
 1249 	*)	exit 1
 1250 .br
 1251 		;;
 1252 .br
 1253 	esac
 1254 .br
 1255 	exit $?
 1256 .br
 1257 .PP
 1258 To use this script, put it where it can be executed and set
 1259 LESSOPEN="|lesspipe.sh %s".
 1260 .PP
 1261 Note that a preprocessor cannot output an empty file, since that
 1262 is interpreted as meaning there is no replacement, and
 1263 the original file is used.
 1264 To avoid this, if LESSOPEN starts with two vertical bars,
 1265 the exit status of the script becomes meaningful.
 1266 If the exit status is zero, the output is considered to be
 1267 replacement text, even if it is empty.
 1268 If the exit status is nonzero, any output is ignored and the
 1269 original file is used.
 1270 For compatibility with previous versions of
 1271 .IR less ,
 1272 if LESSOPEN starts with only one vertical bar, the exit status
 1273 of the preprocessor is ignored.
 1274 .PP
 1275 When an input pipe is used, a LESSCLOSE postprocessor can be used,
 1276 but it is usually not necessary since there is no replacement file
 1277 to clean up.
 1278 In this case, the replacement file name passed to the LESSCLOSE
 1279 postprocessor is "\-".
 1280 .PP
 1281 For compatibility with previous versions of
 1282 .IR less ,
 1283 the input preprocessor or pipe is not used if
 1284 .I less
 1285 is viewing standard input.
 1286 However, if the first character of LESSOPEN is a dash (\-),
 1287 the input preprocessor is used on standard input as well as other files.
 1288 In this case, the dash is not considered to be part of
 1289 the preprocessor command.
 1290 If standard input is being viewed, the input preprocessor is passed
 1291 a file name consisting of a single dash.
 1292 Similarly, if the first two characters of LESSOPEN are vertical bar and dash
 1293 (|\-) or two vertical bars and a dash (||\-),
 1294 the input pipe is used on standard input as well as other files.
 1295 Again, in this case the dash is not considered to be part of
 1296 the input pipe command.
 1297 .
 1298 .SH "NATIONAL CHARACTER SETS"
 1299 There are three types of characters in the input file:
 1300 .IP "normal characters"
 1301 can be displayed directly to the screen.
 1302 .IP "control characters"
 1303 should not be displayed directly, but are expected to be found
 1304 in ordinary text files (such as backspace and tab).
 1305 .IP "binary characters"
 1306 should not be displayed directly and are not expected to be found
 1307 in text files.
 1308 .PP
 1309 A "character set" is simply a description of which characters are to
 1310 be considered normal, control, and binary.
 1311 The LESSCHARSET environment variable may be used to select a character set.
 1312 Possible values for LESSCHARSET are:
 1313 .IP ascii
 1314 BS, TAB, NL, CR, and formfeed are control characters,
 1315 all chars with values between 32 and 126 are normal,
 1316 and all others are binary.
 1317 .IP iso8859
 1318 Selects an ISO 8859 character set.
 1319 This is the same as ASCII, except characters between 160 and 255 are
 1320 treated as normal characters.
 1321 .IP latin1
 1322 Same as iso8859.
 1323 .IP latin9
 1324 Same as iso8859.
 1325 .IP dos
 1326 Selects a character set appropriate for MS-DOS.
 1327 .IP ebcdic
 1328 Selects an EBCDIC character set.
 1329 .IP IBM-1047
 1330 Selects an EBCDIC character set used by OS/390 Unix Services.
 1331 This is the EBCDIC analogue of latin1.  You get similar results
 1332 by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US
 1333 in your environment.
 1334 .IP koi8-r
 1335 Selects a Russian character set.
 1336 .IP next
 1337 Selects a character set appropriate for NeXT computers.
 1338 .IP utf-8
 1339 Selects the UTF-8 encoding of the ISO 10646 character set.
 1340 UTF-8 is special in that it supports multi-byte characters in the input file.
 1341 It is the only character set that supports multi-byte characters.
 1342 .IP windows
 1343 Selects a character set appropriate for Microsoft Windows (cp 1251).
 1344 .PP
 1345 In rare cases, it may be desired to tailor
 1346 .I less
 1347 to use a character set other than the ones definable by LESSCHARSET.
 1348 In this case, the environment variable LESSCHARDEF can be used
 1349 to define a character set.
 1350 It should be set to a string where each character in the string represents
 1351 one character in the character set.
 1352 The character ".\&" is used for a normal character, "c" for control,
 1353 and "b" for binary.
 1354 A decimal number may be used for repetition.
 1355 For example, "bccc4b.\&" would mean character 0 is binary,
 1356 1, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8 is normal.
 1357 All characters after the last are taken to be the same as the last,
 1358 so characters 9 through 255 would be normal.
 1359 (This is an example, and does not necessarily
 1360 represent any real character set.)
 1361 .PP
 1362 This table shows the value of LESSCHARDEF which is equivalent
 1363 to each of the possible values for LESSCHARSET:
 1364 .
 1365 .RS 5m
 1366 .TS
 1367 l l.
 1368 ascii	8bcccbcc18b95.b
 1369 dos	8bcccbcc12bc5b95.b.
 1370 ebcdic	5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
 1371 	9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
 1372 IBM-1047	4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
 1373 	191.b
 1374 iso8859	8bcccbcc18b95.33b.
 1375 koi8-r	8bcccbcc18b95.b128.
 1376 latin1	8bcccbcc18b95.33b.
 1377 next	8bcccbcc18b95.bb125.bb
 1378 .TE
 1379 .RE
 1380 .PP
 1381 If neither LESSCHARSET nor LESSCHARDEF is set,
 1382 but any of the strings "UTF-8", "UTF8", "utf-8" or "utf8"
 1383 is found in the LC_ALL, LC_CTYPE or LANG
 1384 environment variables, then the default character set is utf-8.
 1385 .PP
 1386 If that string is not found, but your system supports the
 1387 .I setlocale
 1388 interface,
 1389 .I less
 1390 will use setlocale to determine the character set.
 1391 setlocale is controlled by setting the LANG or LC_CTYPE environment
 1392 variables.
 1393 .PP
 1394 Finally, if the
 1395 .I setlocale
 1396 interface is also not available, the default character set is latin1.
 1397 .PP
 1398 Control and binary characters are displayed in standout (reverse video).
 1399 Each such character is displayed in caret notation if possible
 1400 (e.g.\& ^A for control-A).  Caret notation is used only if
 1401 inverting the 0100 bit results in a normal printable character.
 1402 Otherwise, the character is displayed as a hex number in angle brackets.
 1403 This format can be changed by
 1404 setting the LESSBINFMT environment variable.
 1405 LESSBINFMT may begin with a "*" and one character to select
 1406 the display attribute:
 1407 "*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout,
 1408 and "*n" is normal.
 1409 If LESSBINFMT does not begin with a "*", normal attribute is assumed.
 1410 The remainder of LESSBINFMT is a string which may include one
 1411 printf-style escape sequence (a % followed by x, X, o, d, etc.).
 1412 For example, if LESSBINFMT is "*u[%x]", binary characters
 1413 are displayed in underlined hexadecimal surrounded by brackets.
 1414 The default if no LESSBINFMT is specified is "*s<%02X>".
 1415 Warning: the result of expanding the character via LESSBINFMT must
 1416 be less than 31 characters.
 1417 .PP
 1418 When the character set is utf-8, the LESSUTFBINFMT environment variable
 1419 acts similarly to LESSBINFMT but it applies to Unicode code points
 1420 that were successfully decoded but are unsuitable for display (e.g.,
 1421 unassigned code points).
 1422 Its default value is "<U+%04lX>".
 1423 Note that LESSUTFBINFMT and LESSBINFMT share their display attribute
 1424 setting ("*x") so specifying one will affect both;
 1425 LESSUTFBINFMT is read after LESSBINFMT so its setting, if any,
 1426 will have priority.
 1427 Problematic octets in a UTF-8 file (octets of a truncated sequence,
 1428 octets of a complete but non-shortest form sequence, invalid octets,
 1429 and stray trailing octets)
 1430 are displayed individually using LESSBINFMT so as to facilitate diagnostic
 1431 of how the UTF-8 file is ill-formed.
 1432 .
 1433 .SH "PROMPTS"
 1434 The \-P option allows you to tailor the prompt to your preference.
 1435 The string given to the \-P option replaces the specified prompt string.
 1436 Certain characters in the string are interpreted specially.
 1437 The prompt mechanism is rather complicated to provide flexibility,
 1438 but the ordinary user need not understand the details of constructing
 1439 personalized prompt strings.
 1440 .sp
 1441 A percent sign followed by a single character is expanded
 1442 according to what the following character is:
 1443 .IP "%b\fIX\fP"
 1444 Replaced by the byte offset into the current input file.
 1445 The b is followed by a single character (shown as \fIX\fP above)
 1446 which specifies the line whose byte offset is to be used.
 1447 If the character is a "t", the byte offset of the top line in the
 1448 display is used,
 1449 an "m" means use the middle line,
 1450 a "b" means use the bottom line,
 1451 a "B" means use the line just after the bottom line,
 1452 and a "j" means use the "target" line, as specified by the \-j option.
 1453 .IP "%B"
 1454 Replaced by the size of the current input file.
 1455 .IP "%c"
 1456 Replaced by the column number of the text appearing in the first
 1457 column of the screen.
 1458 .IP "%d\fIX\fP"
 1459 Replaced by the page number of a line in the input file.
 1460 The line to be used is determined by the \fIX\fP, as with the %b option.
 1461 .IP "%D"
 1462 Replaced by the number of pages in the input file,
 1463 or equivalently, the page number of the last line in the input file.
 1464 .IP "%E"
 1465 Replaced by the name of the editor (from the VISUAL environment variable,
 1466 or the EDITOR environment variable if VISUAL is not defined).
 1467 See the discussion of the LESSEDIT feature below.
 1468 .IP "%f"
 1469 Replaced by the name of the current input file.
 1470 .IP "%F"
 1471 Replaced by the last component of the name of the current input file.
 1472 .IP "%g"
 1473 Replaced by the shell-escaped name of the current input file.
 1474 This is useful when the expanded string will be used in a shell command,
 1475 such as in LESSEDIT.
 1476 .IP "%i"
 1477 Replaced by the index of the current file in the list of
 1478 input files.
 1479 .IP "%l\fIX\fP"
 1480 Replaced by the line number of a line in the input file.
 1481 The line to be used is determined by the \fIX\fP, as with the %b option.
 1482 .IP "%L"
 1483 Replaced by the line number of the last line in the input file.
 1484 .IP "%m"
 1485 Replaced by the total number of input files.
 1486 .IP "%p\fIX\fP"
 1487 Replaced by the percent into the current input file, based on byte offsets.
 1488 The line used is determined by the \fIX\fP as with the %b option.
 1489 .IP "%P\fIX\fP"
 1490 Replaced by the percent into the current input file, based on line numbers.
 1491 The line used is determined by the \fIX\fP as with the %b option.
 1492 .IP "%s"
 1493 Same as %B.
 1494 .IP "%t"
 1495 Causes any trailing spaces to be removed.
 1496 Usually used at the end of the string, but may appear anywhere.
 1497 .IP "%T"
 1498 Normally expands to the word "file".
 1499 However if viewing files via a tags list using the \-t option,
 1500 it expands to the word "tag".
 1501 .IP "%x"
 1502 Replaced by the name of the next input file in the list.
 1503 .PP
 1504 If any item is unknown (for example, the file size if input
 1505 is a pipe), a question mark is printed instead.
 1506 .PP
 1507 The format of the prompt string can be changed
 1508 depending on certain conditions.
 1509 A question mark followed by a single character acts like an "IF":
 1510 depending on the following character, a condition is evaluated.
 1511 If the condition is true, any characters following the question mark
 1512 and condition character, up to a period, are included in the prompt.
 1513 If the condition is false, such characters are not included.
 1514 A colon appearing between the question mark and the
 1515 period can be used to establish an "ELSE": any characters between
 1516 the colon and the period are included in the string if and only if
 1517 the IF condition is false.
 1518 Condition characters (which follow a question mark) may be:
 1519 .IP "?a"
 1520 True if any characters have been included in the prompt so far.
 1521 .IP "?b\fIX\fP"
 1522 True if the byte offset of the specified line is known.
 1523 .IP "?B"
 1524 True if the size of current input file is known.
 1525 .IP "?c"
 1526 True if the text is horizontally shifted (%c is not zero).
 1527 .IP "?d\fIX\fP"
 1528 True if the page number of the specified line is known.
 1529 .IP "?e"
 1530 True if at end-of-file.
 1531 .IP "?f"
 1532 True if there is an input filename
 1533 (that is, if input is not a pipe).
 1534 .IP "?l\fIX\fP"
 1535 True if the line number of the specified line is known.
 1536 .IP "?L"
 1537 True if the line number of the last line in the file is known.
 1538 .IP "?m"
 1539 True if there is more than one input file.
 1540 .IP "?n"
 1541 True if this is the first prompt in a new input file.
 1542 .IP "?p\fIX\fP"
 1543 True if the percent into the current input file, based on byte offsets,
 1544 of the specified line is known.
 1545 .IP "?P\fIX\fP"
 1546 True if the percent into the current input file, based on line numbers,
 1547 of the specified line is known.
 1548 .IP "?s"
 1549 Same as "?B".
 1550 .IP "?x"
 1551 True if there is a next input file
 1552 (that is, if the current input file is not the last one).
 1553 .PP
 1554 Any characters other than the special ones
 1555 (question mark, colon, period, percent, and backslash)
 1556 become literally part of the prompt.
 1557 Any of the special characters may be included in the prompt literally
 1558 by preceding it with a backslash.
 1559 .PP
 1560 Some examples:
 1561 .sp
 1562 ?f%f:Standard input.
 1563 .sp
 1564 This prompt prints the filename, if known;
 1565 otherwise the string "Standard input".
 1566 .sp
 1567 ?f%f \&.?ltLine %lt:?pt%pt\e%:?btByte %bt:-...
 1568 .sp
 1569 This prompt would print the filename, if known.
 1570 The filename is followed by the line number, if known,
 1571 otherwise the percent if known, otherwise the byte offset if known.
 1572 Otherwise, a dash is printed.
 1573 Notice how each question mark has a matching period,
 1574 and how the % after the %pt
 1575 is included literally by escaping it with a backslash.
 1576 .sp
 1577 ?n?f%f\ .?m(%T %i of %m)\ ..?e(END)\ ?x-\ Next\e:\ %x..%t";
 1578 .sp
 1579 This prints the filename if this is the first prompt in a file,
 1580 followed by the "file N of N" message if there is more
 1581 than one input file.
 1582 Then, if we are at end-of-file, the string "(END)" is printed
 1583 followed by the name of the next file, if there is one.
 1584 Finally, any trailing spaces are truncated.
 1585 This is the default prompt.
 1586 For reference, here are the defaults for
 1587 the other two prompts (\-m and \-M respectively).
 1588 Each is broken into two lines here for readability only.
 1589 .nf
 1590 .sp
 1591 ?n?f%f\ .?m(%T\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x.:
 1592 	?pB%pB\e%:byte\ %bB?s/%s...%t
 1593 .sp
 1594 ?f%f\ .?n?m(%T\ %i\ of\ %m)\ ..?ltlines\ %lt-%lb?L/%L.\ :
 1595 	byte\ %bB?s/%s.\ .?e(END)\ ?x-\ Next\e:\ %x.:?pB%pB\e%..%t
 1596 .sp
 1597 .fi
 1598 And here is the default message produced by the = command:
 1599 .nf
 1600 .sp
 1601 ?f%f\ .?m(%T\ %i\ of\ %m)\ .?ltlines\ %lt-%lb?L/%L.\ .
 1602 	byte\ %bB?s/%s.\ ?e(END)\ :?pB%pB\e%..%t
 1603 .fi
 1604 .PP
 1605 The prompt expansion features are also used for another purpose:
 1606 if an environment variable LESSEDIT is defined, it is used
 1607 as the command to be executed when the v command is invoked.
 1608 The LESSEDIT string is expanded in the same way as the prompt strings.
 1609 The default value for LESSEDIT is:
 1610 .nf
 1611 .sp
 1612 	%E\ ?lm+%lm.\ %g
 1613 .sp
 1614 .fi
 1615 Note that this expands to the editor name, followed by a + and the
 1616 line number, followed by the shell-escaped file name.
 1617 If your editor does not accept the "+linenumber" syntax, or has other
 1618 differences in invocation syntax, the LESSEDIT variable can be
 1619 changed to modify this default.
 1620 .
 1621 .SH SECURITY
 1622 When the environment variable LESSSECURE is set to 1,
 1623 .I less
 1624 runs in a "secure" mode.
 1625 This means these features are disabled:
 1626 .RS
 1627 .IP "!"
 1628 the shell command
 1629 .IP "|"
 1630 the pipe command
 1631 .IP ":e"
 1632 the examine command.
 1633 .IP "v"
 1634 the editing command
 1635 .IP "s  \-o"
 1636 log files
 1637 .IP "\-k"
 1638 use of lesskey files
 1639 .IP "\-t"
 1640 use of tags files
 1641 .IP
 1642 metacharacters in filenames, such as *
 1643 .IP
 1644 filename completion (TAB, ^L)
 1645 .RE
 1646 .PP
 1647 Less can also be compiled to be permanently in "secure" mode.
 1648 .
 1649 .SH "COMPATIBILITY WITH MORE"
 1650 If the environment variable LESS_IS_MORE is set to 1,
 1651 or if the program is invoked via a file link named "more",
 1652 .I less
 1653 behaves (mostly) in conformance with the POSIX "more" command specification.
 1654 In this mode, less behaves differently in these ways:
 1655 .PP
 1656 The \-e option works differently.
 1657 If the \-e option is not set,
 1658 .I less
 1659 behaves as if the \-e option were set.
 1660 If the \-e option is set,
 1661 .I less
 1662 behaves as if the \-E option were set.
 1663 .PP
 1664 The \-m option works differently.
 1665 If the \-m option is not set, the medium prompt is used,
 1666 and it is prefixed with the string "\-\-More\-\-".
 1667 If the \-m option is set, the short prompt is used.
 1668 .PP
 1669 The \-n option acts like the \-z option.
 1670 The normal behavior of the \-n option is unavailable in this mode.
 1671 .PP
 1672 The parameter to the \-p option is taken to be a
 1673 .I less
 1674 command rather than a search pattern.
 1675 .PP
 1676 The LESS environment variable is ignored,
 1677 and the MORE environment variable is used in its place.
 1678 .
 1679 .SH "ENVIRONMENT VARIABLES"
 1680 Environment variables may be specified either in the system environment
 1681 as usual, or in a
 1682 .IR lesskey (1)
 1683 file.
 1684 If environment variables are defined in more than one place,
 1685 variables defined in a local lesskey file take precedence over
 1686 variables defined in the system environment, which take precedence
 1687 over variables defined in the system-wide lesskey file.
 1688 .IP COLUMNS
 1689 Sets the number of columns on the screen.
 1690 Takes precedence over the number of columns specified by the TERM variable.
 1691 (But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD,
 1692 the window system's idea of the screen size takes precedence over the
 1693 LINES and COLUMNS environment variables.)
 1694 .IP EDITOR
 1695 The name of the editor (used for the v command).
 1696 .IP HOME
 1697 Name of the user's home directory
 1698 (used to find a lesskey file on Unix and OS/2 systems).
 1699 .IP "HOMEDRIVE, HOMEPATH"
 1700 Concatenation of the HOMEDRIVE and HOMEPATH environment variables is
 1701 the name of the user's home directory if the HOME variable is not set
 1702 (only in the Windows version).
 1703 .IP INIT
 1704 Name of the user's init directory (used to find a lesskey file on OS/2 systems).
 1705 .IP LANG
 1706 Language for determining the character set.
 1707 .IP LC_CTYPE
 1708 Language for determining the character set.
 1709 .IP LESS
 1710 Options which are passed to
 1711 .I less
 1712 automatically.
 1713 .IP LESSANSIENDCHARS
 1714 Characters which may end an ANSI color escape sequence
 1715 (default "m").
 1716 .IP LESSANSIMIDCHARS
 1717 Characters which may appear between the ESC character and the
 1718 end character in an ANSI color escape sequence
 1719 (default "0123456789:;[?!"'#%()*+\ ".
 1720 .IP LESSBINFMT
 1721 Format for displaying non-printable, non-control characters.
 1722 .IP LESSCHARDEF
 1723 Defines a character set.
 1724 .IP LESSCHARSET
 1725 Selects a predefined character set.
 1726 .IP LESSCLOSE
 1727 Command line to invoke the (optional) input-postprocessor.
 1728 .IP LESSECHO
 1729 Name of the lessecho program (default "lessecho").
 1730 The lessecho program is needed to expand metacharacters, such as * and ?,
 1731 in filenames on Unix systems.
 1732 .IP LESSEDIT
 1733 Editor prototype string (used for the v command).
 1734 See discussion under PROMPTS.
 1735 .IP LESSGLOBALTAGS
 1736 Name of the command used by the \-t option to find global tags.
 1737 Normally should be set to "global" if your system has the
 1738 .IR global (1)
 1739 command.  If not set, global tags are not used.
 1740 .IP LESSHISTFILE
 1741 Name of the history file used to remember search commands and
 1742 shell commands between invocations of
 1743 .IR less .
 1744 If set to "\-" or "/dev/null", a history file is not used.
 1745 The default is "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on
 1746 DOS and Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini"
 1747 on OS/2 systems.
 1748 .IP LESSHISTSIZE
 1749 The maximum number of commands to save in the history file.
 1750 The default is 100.
 1751 .IP LESSKEY
 1752 Name of the default
 1753 .IR lesskey (1)
 1754 file.
 1755 .IP LESSKEY_SYSTEM
 1756 Name of the default system-wide
 1757 .IR lesskey (1)
 1758 file.
 1759 .IP LESSMETACHARS
 1760 List of characters which are considered "metacharacters" by the shell.
 1761 .IP LESSMETAESCAPE
 1762 Prefix which less will add before each metacharacter in a
 1763 command sent to the shell.
 1764 If LESSMETAESCAPE is an empty string, commands containing
 1765 metacharacters will not be passed to the shell.
 1766 .IP LESSOPEN
 1767 Command line to invoke the (optional) input-preprocessor.
 1768 .IP LESSSECURE
 1769 Runs less in "secure" mode.
 1770 See discussion under SECURITY.
 1771 .IP LESSSEPARATOR
 1772 String to be appended to a directory name in filename completion.
 1773 .IP LESSUTFBINFMT
 1774 Format for displaying non-printable Unicode code points.
 1775 .IP LESS_IS_MORE
 1776 Emulate the
 1777 .IR more (1)
 1778 command.
 1779 .IP LINES
 1780 Sets the number of lines on the screen.
 1781 Takes precedence over the number of lines specified by the TERM variable.
 1782 (But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD,
 1783 the window system's idea of the screen size takes precedence over the
 1784 LINES and COLUMNS environment variables.)
 1785 .IP MORE
 1786 Options which are passed to
 1787 .I less
 1788 automatically when running in
 1789 .I more
 1790 compatible mode.
 1791 .IP PATH
 1792 User's search path (used to find a lesskey file
 1793 on MS-DOS and OS/2 systems).
 1794 .IP SHELL
 1795 The shell used to execute the !\& command, as well as to expand filenames.
 1796 .IP TERM
 1797 The type of terminal on which
 1798 .I less
 1799 is being run.
 1800 .IP VISUAL
 1801 The name of the editor (used for the v command).
 1802 .
 1803 .SH "SEE ALSO"
 1804 .BR lesskey (1)
 1805 .
 1806 .SH COPYRIGHT
 1807 Copyright (C) 1984-2020  Mark Nudelman
 1808 .PP
 1809 less is part of the GNU project and is free software.
 1810 You can redistribute it and/or modify it
 1811 under the terms of either
 1812 (1) the GNU General Public License as published by
 1813 the Free Software Foundation; or (2) the Less License.
 1814 See the file README in the less distribution for more details
 1815 regarding redistribution.
 1816 You should have received a copy of the GNU General Public License
 1817 along with the source for less; see the file COPYING.
 1818 If not, write to the Free Software Foundation, 59 Temple Place,
 1819 Suite 330, Boston, MA  02111-1307, USA.
 1820 You should also have received a copy of the Less License;
 1821 see the file LICENSE.
 1822 .PP
 1823 less is distributed in the hope that it will be useful, but
 1824 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 1825 or FITNESS FOR A PARTICULAR PURPOSE.
 1826 See the GNU General Public License for more details.
 1827 .
 1828 .SH AUTHOR
 1829 .
 1830 Mark Nudelman
 1831 .br
 1832 Report bugs at https://github.com/gwsw/less/issues.
 1833 .br
 1834 For more information, see the less homepage at
 1835 .br
 1836 http://www.greenwoodsoftware.com/less.