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diff --git a/less.nro b/less.nro new file mode 100644 index 0000000..9c00d21 --- /dev/null +++ b/less.nro @@ -0,0 +1,1750 @@ +.TH LESS 1 "Version 451: 21 Jul 2012" +.SH NAME +less \- opposite of more +.SH SYNOPSIS +.B "less \-?" +.br +.B "less \-\-help" +.br +.B "less \-V" +.br +.B "less \-\-version" +.br +.B "less [\-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]" +.br +.B " [\-b \fIspace\fP] [\-h \fIlines\fP] [\-j \fIline\fP] [\-k \fIkeyfile\fP]" +.br +.B " [\-{oO} \fIlogfile\fP] [\-p \fIpattern\fP] [\-P \fIprompt\fP] [\-t \fItag\fP]" +.br +.B " [\-T \fItagsfile\fP] [\-x \fItab\fP,...] [\-y \fIlines\fP] [\-[z] \fIlines\fP]" +.br +.B " [\-# \fIshift\fP] [+[+]\fIcmd\fP] [\-\-] [\fIfilename\fP]..." +.br +(See the OPTIONS section for alternate option syntax with long option names.) + +.SH DESCRIPTION +.I Less +is a program similar to +.I more +(1), but which allows backward movement +in the file as well as forward movement. +Also, +.I less +does not have to read the entire input file before starting, +so with large input files it starts up faster than text editors like +.I vi +(1). +.I Less +uses termcap (or terminfo on some systems), +so it can run on a variety of terminals. +There is even limited support for hardcopy terminals. +(On a hardcopy terminal, lines which should be printed at the top +of the screen are prefixed with a caret.) +.PP +Commands are based on both +.I more +and +.I vi. +Commands may be preceded by a decimal number, +called N in the descriptions below. +The number is used by some commands, as indicated. + +.SH COMMANDS +In the following descriptions, ^X means control-X. +ESC stands for the ESCAPE key; for example ESC-v means the +two character sequence "ESCAPE", then "v". +.IP "h or H" +Help: display a summary of these commands. +If you forget all the other commands, remember this one. +.IP "SPACE or ^V or f or ^F" +Scroll forward N lines, default one window (see option \-z below). +If N is more than the screen size, only the final screenful is displayed. +Warning: some systems use ^V as a special literalization character. +.IP "z" +Like SPACE, but if N is specified, it becomes the new window size. +.IP "ESC-SPACE" +Like SPACE, but scrolls a full screenful, even if it reaches +end-of-file in the process. +.IP "ENTER or RETURN or ^N or e or ^E or j or ^J" +Scroll forward N lines, default 1. +The entire N lines are displayed, even if N is more than the screen size. +.IP "d or ^D" +Scroll forward N lines, default one half of the screen size. +If N is specified, it becomes the new default for +subsequent d and u commands. +.IP "b or ^B or ESC-v" +Scroll backward N lines, default one window (see option \-z below). +If N is more than the screen size, only the final screenful is displayed. +.IP "w" +Like ESC-v, but if N is specified, it becomes the new window size. +.IP "y or ^Y or ^P or k or ^K" +Scroll backward N lines, default 1. +The entire N lines are displayed, even if N is more than the screen size. +Warning: some systems use ^Y as a special job control character. +.IP "u or ^U" +Scroll backward N lines, default one half of the screen size. +If N is specified, it becomes the new default for +subsequent d and u commands. +.IP "ESC-) or RIGHTARROW" +Scroll horizontally right N characters, default half the screen width +(see the \-# option). +If a number N is specified, it becomes the default for future RIGHTARROW +and LEFTARROW commands. +While the text is scrolled, it acts as though the \-S option +(chop lines) were in effect. +.IP "ESC-( or LEFTARROW" +Scroll horizontally left N characters, default half the screen width +(see the \-# option). +If a number N is specified, it becomes the default for future RIGHTARROW +and LEFTARROW commands. +.IP "r or ^R or ^L" +Repaint the screen. +.IP R +Repaint the screen, discarding any buffered input. +Useful if the file is changing while it is being viewed. +.IP "F" +Scroll forward, and keep trying to read when the +end of file is reached. +Normally this command would be used when already at the end of the file. +It is a way to monitor the tail of a file which is growing +while it is being viewed. +(The behavior is similar to the "tail \-f" command.) +.IP "ESC-F" +Like F, but as soon as a line is found which matches +the last search pattern, the terminal bell is rung +and forward scrolling stops. +.IP "g or < or ESC-<" +Go to line N in the file, default 1 (beginning of file). +(Warning: this may be slow if N is large.) +.IP "G or > or ESC->" +Go to line N in the file, default the end of the file. +(Warning: this may be slow if N is large, +or if N is not specified and +standard input, rather than a file, is being read.) +.IP "p or %" +Go to a position N percent into the file. +N should be between 0 and 100, and may contain a decimal point. +.IP "P" +Go to the line containing byte offset N in the file. +.IP "{" +If a left curly bracket appears in the top line displayed +on the screen, +the { command will go to the matching right curly bracket. +The matching right curly bracket is positioned on the bottom +line of the screen. +If there is more than one left curly bracket on the top line, +a number N may be used to specify the N-th bracket on the line. +.IP "}" +If a right curly bracket appears in the bottom line displayed +on the screen, +the } command will go to the matching left curly bracket. +The matching left curly bracket is positioned on the top +line of the screen. +If there is more than one right curly bracket on the top line, +a number N may be used to specify the N-th bracket on the line. +.IP "(" +Like {, but applies to parentheses rather than curly brackets. +.IP ")" +Like }, but applies to parentheses rather than curly brackets. +.IP "[" +Like {, but applies to square brackets rather than curly brackets. +.IP "]" +Like }, but applies to square brackets rather than curly brackets. +.IP "ESC-^F" +Followed by two characters, +acts like {, but uses the two characters as open and close brackets, +respectively. +For example, "ESC ^F < >" could be used to +go forward to the > which matches the < in the top displayed line. +.IP "ESC-^B" +Followed by two characters, +acts like }, but uses the two characters as open and close brackets, +respectively. +For example, "ESC ^B < >" could be used to +go backward to the < which matches the > in the bottom displayed line. +.IP m +Followed by any lowercase letter, +marks the current position with that letter. +.IP "'" +(Single quote.) +Followed by any lowercase letter, returns to the position which +was previously marked with that letter. +Followed by another single quote, returns to the position at +which the last "large" movement command was executed. +Followed by a ^ or $, jumps to the beginning or end of the +file respectively. +Marks are preserved when a new file is examined, +so the ' command can be used to switch between input files. +.IP "^X^X" +Same as single quote. +.IP /pattern +Search forward in the file for the N-th line containing the pattern. +N defaults to 1. +The pattern is a regular expression, as recognized by +the regular expression library supplied by your system. +The search starts at the first line displayed +(but see the \-a and \-j options, which change this). +.sp +Certain characters are special +if entered at the beginning of the pattern; +they modify the type of search rather than become part of the pattern: +.RS +.IP "^N or !" +Search for lines which do NOT match the pattern. +.IP "^E or *" +Search multiple files. +That is, if the search reaches the END of the current file +without finding a match, +the search continues in the next file in the command line list. +.IP "^F or @" +Begin the search at the first line of the FIRST file +in the command line list, +regardless of what is currently displayed on the screen +or the settings of the \-a or \-j options. +.IP "^K" +Highlight any text which matches the pattern on the current screen, +but don't move to the first match (KEEP current position). +.IP "^R" +Don't interpret regular expression metacharacters; +that is, do a simple textual comparison. +.RE +.IP ?pattern +Search backward in the file for the N-th line containing the pattern. +The search starts at the line immediately before the top line displayed. +.sp +Certain characters are special as in the / command: +.RS +.IP "^N or !" +Search for lines which do NOT match the pattern. +.IP "^E or *" +Search multiple files. +That is, if the search reaches the beginning of the current file +without finding a match, +the search continues in the previous file in the command line list. +.IP "^F or @" +Begin the search at the last line of the last file +in the command line list, +regardless of what is currently displayed on the screen +or the settings of the \-a or \-j options. +.IP "^K" +As in forward searches. +.IP "^R" +As in forward searches. +.RE +.IP "ESC-/pattern" +Same as "/*". +.IP "ESC-?pattern" +Same as "?*". +.IP n +Repeat previous search, for N-th line containing the last pattern. +If the previous search was modified by ^N, the search is made for the +N-th line NOT containing the pattern. +If the previous search was modified by ^E, the search continues +in the next (or previous) file if not satisfied in the current file. +If the previous search was modified by ^R, the search is done +without using regular expressions. +There is no effect if the previous search was modified by ^F or ^K. +.IP N +Repeat previous search, but in the reverse direction. +.IP "ESC-n" +Repeat previous search, but crossing file boundaries. +The effect is as if the previous search were modified by *. +.IP "ESC-N" +Repeat previous search, but in the reverse direction +and crossing file boundaries. +.IP "ESC-u" +Undo search highlighting. +Turn off highlighting of strings matching the current search pattern. +If highlighting is already off because of a previous ESC-u command, +turn highlighting back on. +Any search command will also turn highlighting back on. +(Highlighting can also be disabled by toggling the \-G option; +in that case search commands do not turn highlighting back on.) +.IP "&pattern" +Display only lines which match the pattern; +lines which do not match the pattern are not displayed. +If pattern is empty (if you type & immediately followed by ENTER), +any filtering is turned off, and all lines are displayed. +While filtering is in effect, an ampersand is displayed at the +beginning of the prompt, +as a reminder that some lines in the file may be hidden. +.sp +Certain characters are special as in the / command: +.RS +.IP "^N or !" +Display only lines which do NOT match the pattern. +.IP "^R" +Don't interpret regular expression metacharacters; +that is, do a simple textual comparison. +.RE +.IP ":e [filename]" +Examine a new file. +If the filename is missing, the "current" file (see the :n and :p commands +below) from the list of files in the command line is re-examined. +A percent sign (%) in the filename is replaced by the name of the +current file. +A pound sign (#) is replaced by the name of the previously examined file. +However, two consecutive percent signs are simply +replaced with a single percent sign. +This allows you to enter a filename that contains a percent sign +in the name. +Similarly, two consecutive pound signs are replaced with a single pound sign. +The filename is inserted into the command line list of files +so that it can be seen by subsequent :n and :p commands. +If the filename consists of several files, they are all inserted into +the list of files and the first one is examined. +If the filename contains one or more spaces, +the entire filename should be enclosed in double quotes +(also see the \-" option). +.IP "^X^V or E" +Same as :e. +Warning: some systems use ^V as a special literalization character. +On such systems, you may not be able to use ^V. +.IP ":n" +Examine the next file (from the list of files given in the command line). +If a number N is specified, the N-th next file is examined. +.IP ":p" +Examine the previous file in the command line list. +If a number N is specified, the N-th previous file is examined. +.IP ":x" +Examine the first file in the command line list. +If a number N is specified, the N-th file in the list is examined. +.IP ":d" +Remove the current file from the list of files. +.IP "t" +Go to the next tag, if there were more than one matches for the current tag. +See the \-t option for more details about tags. +.IP "T" +Go to the previous tag, if there were more than one matches for the current tag. +.IP "= or ^G or :f" +Prints some information about the file being viewed, +including its name +and the line number and byte offset of the bottom line being displayed. +If possible, it also prints the length of the file, +the number of lines in the file +and the percent of the file above the last displayed line. +.IP \- +Followed by one of the command line option letters (see OPTIONS below), +this will change the setting of that option +and print a message describing the new setting. +If a ^P (CONTROL-P) is entered immediately after the dash, +the setting of the option is changed but no message is printed. +If the option letter has a numeric value (such as \-b or \-h), +or a string value (such as \-P or \-t), +a new value may be entered after the option letter. +If no new value is entered, a message describing +the current setting is printed and nothing is changed. +.IP \-\- +Like the \- command, but takes a long option name (see OPTIONS below) +rather than a single option letter. +You must press ENTER or RETURN after typing the option name. +A ^P immediately after the second dash suppresses printing of a +message describing the new setting, as in the \- command. +.IP \-+ +Followed by one of the command line option letters +this will reset the option to its default setting +and print a message describing the new setting. +(The "\-+\fIX\fP" command does the same thing +as "\-+\fIX\fP" on the command line.) +This does not work for string-valued options. +.IP \-\-+ +Like the \-+ command, but takes a long option name +rather than a single option letter. +.IP \-! +Followed by one of the command line option letters, +this will reset the option to the "opposite" of its default setting +and print a message describing the new setting. +This does not work for numeric or string-valued options. +.IP \-\-! +Like the \-! command, but takes a long option name +rather than a single option letter. +.IP _ +(Underscore.) +Followed by one of the command line option letters, +this will print a message describing the current setting of that option. +The setting of the option is not changed. +.IP __ +(Double underscore.) +Like the _ (underscore) command, but takes a long option name +rather than a single option letter. +You must press ENTER or RETURN after typing the option name. +.IP +cmd +Causes the specified cmd to be executed each time a new file is examined. +For example, +G causes +.I less +to initially display each file starting at the end +rather than the beginning. +.IP V +Prints the version number of +.I less +being run. +.IP "q or Q or :q or :Q or ZZ" +Exits +.I less. +.PP +The following +four +commands may or may not be valid, depending on your particular installation. +.PP +.IP v +Invokes an editor to edit the current file being viewed. +The editor is taken from the environment variable VISUAL if defined, +or EDITOR if VISUAL is not defined, +or defaults to "vi" if neither VISUAL nor EDITOR is defined. +See also the discussion of LESSEDIT under the section on PROMPTS below. +.IP "! shell-command" +Invokes a shell to run the shell-command given. +A percent sign (%) in the command is replaced by the name of the +current file. +A pound sign (#) is replaced by the name of the previously examined file. +"!!" repeats the last shell command. +"!" with no shell command simply invokes a shell. +On Unix systems, the shell is taken from the environment variable SHELL, +or defaults to "sh". +On MS-DOS and OS/2 systems, the shell is the normal command processor. +.IP "| <m> shell-command" +<m> represents any mark letter. +Pipes a section of the input file to the given shell command. +The section of the file to be piped is between the first line on +the current screen and the position marked by the letter. +<m> may also be ^ or $ to indicate beginning or end of file respectively. +If <m> is . or newline, the current screen is piped. +.IP "s filename" +Save the input to a file. +This only works if the input is a pipe, not an ordinary file. +.PP +.SH OPTIONS +Command line options are described below. +Most options may be changed while +.I less +is running, via the "\-" command. +.PP +Most options may be given in one of two forms: +either a dash followed by a single letter, +or two dashes followed by a long option name. +A long option name may be abbreviated as long as +the abbreviation is unambiguous. +For example, \-\-quit-at-eof may be abbreviated \-\-quit, but not +--qui, since both \-\-quit-at-eof and \-\-quiet begin with \-\-qui. +Some long option names are in uppercase, such as \-\-QUIT-AT-EOF, as +distinct from \-\-quit-at-eof. +Such option names need only have their first letter capitalized; +the remainder of the name may be in either case. +For example, \-\-Quit-at-eof is equivalent to \-\-QUIT-AT-EOF. +.PP +Options are also taken from the environment variable "LESS". +For example, +to avoid typing "less \-options ..." each time +.I less +is invoked, you might tell +.I csh: +.sp +setenv LESS "-options" +.sp +or if you use +.I sh: +.sp +LESS="-options"; export LESS +.sp +On MS-DOS, you don't need the quotes, but you should replace any +percent signs in the options string by double percent signs. +.sp +The environment variable is parsed before the command line, +so command line options override the LESS environment variable. +If an option appears in the LESS variable, it can be reset +to its default value on the command line by beginning the command +line option with "\-+". +.sp +For options like \-P or \-D which take a following string, +a dollar sign ($) must be used to signal the end of the string. +For example, to set two \-D options on MS-DOS, you must have +a dollar sign between them, like this: +.sp +LESS="-Dn9.1$-Ds4.1" +.sp +.IP "\-? or \-\-help" +This option displays a summary of the commands accepted by +.I less +(the same as the h command). +(Depending on how your shell interprets the question mark, +it may be necessary to quote the question mark, thus: "\-\e?".) +.IP "\-a or \-\-search-skip-screen" +By default, forward searches start at the top of the displayed screen +and backwards searches start at the bottom of the displayed screen +(except for repeated searches invoked by the n or N commands, +which start after or before the "target" line respectively; +see the \-j option for more about the target line). +The \-a option causes forward searches to instead start at +the bottom of the screen +and backward searches to start at the top of the screen, +thus skipping all lines displayed on the screen. +.IP "\-A or \-\-SEARCH-SKIP-SCREEN" +Causes all forward searches (not just non-repeated searches) +to start just after the target line, and all backward searches +to start just before the target line. +Thus, forward searches will skip part of the displayed screen +(from the first line up to and including the target line). +Similarly backwards searches will skip the displayed screen +from the last line up to and including the target line. +This was the default behavior in less versions prior to 441. +.IP "\-b\fIn\fP or \-\-buffers=\fIn\fP" +Specifies the amount of buffer space +.I less +will use for each file, in units of kilobytes (1024 bytes). +By default 64K of buffer space is used for each file +(unless the file is a pipe; see the \-B option). +The \-b option specifies instead that \fIn\fP kilobytes of +buffer space should be used for each file. +If \fIn\fP is \-1, buffer space is unlimited; that is, +the entire file can be read into memory. +.IP "\-B or \-\-auto-buffers" +By default, when data is read from a pipe, +buffers are allocated automatically as needed. +If a large amount of data is read from the pipe, this can cause +a large amount of memory to be allocated. +The \-B option disables this automatic allocation of buffers for pipes, +so that only 64K +(or the amount of space specified by the \-b option) +is used for the pipe. +Warning: use of \-B can result in erroneous display, since only the +most recently viewed part of the piped data is kept in memory; +any earlier data is lost. +.IP "\-c or \-\-clear-screen" +Causes full screen repaints to be painted from the top line down. +By default, +full screen repaints are done by scrolling from the bottom of the screen. +.IP "\-C or \-\-CLEAR-SCREEN" +Same as \-c, for compatibility with older versions of +.I less. +.IP "\-d or \-\-dumb" +The \-d option suppresses the error message +normally displayed if the terminal is dumb; +that is, lacks some important capability, +such as the ability to clear the screen or scroll backward. +The \-d option does not otherwise change the behavior of +.I less +on a dumb terminal. +.IP "\-D\fBx\fP\fIcolor\fP or \-\-color=\fBx\fP\fIcolor\fP" +[MS-DOS only] +Sets the color of the text displayed. +\fBx\fP is a single character which selects the type of text whose color is +being set: n=normal, s=standout, d=bold, u=underlined, k=blink. +\fIcolor\fP is a pair of numbers separated by a period. +The first number selects the foreground color and the second selects +the background color of the text. +A single number \fIN\fP is the same as \fIN.M\fP, +where \fIM\fP is the normal background color. + +.IP "\-e or \-\-quit-at-eof" +Causes +.I less +to automatically exit +the second time it reaches end-of-file. +By default, the only way to exit +.I less +is via the "q" command. +.IP "\-E or \-\-QUIT-AT-EOF" +Causes +.I less +to automatically exit the first time it reaches end-of-file. +.IP "\-f or \-\-force" +Forces non-regular files to be opened. +(A non-regular file is a directory or a device special file.) +Also suppresses the warning message when a binary file is opened. +By default, +.I less +will refuse to open non-regular files. +Note that some operating systems will not allow directories +to be read, even if \-f is set. +.IP "\-F or \-\-quit-if-one-screen" +Causes +.I less +to automatically exit +if the entire file can be displayed on the first screen. +.IP "\-g or \-\-hilite-search" +Normally, +.I less +will highlight ALL strings which match the last search command. +The \-g option changes this behavior to highlight only the particular string +which was found by the last search command. +This can cause +.I less +to run somewhat faster than the default. +.IP "\-G or \-\-HILITE-SEARCH" +The \-G option suppresses all highlighting of strings found by search commands. +.IP "\-h\fIn\fP or \-\-max-back-scroll=\fIn\fP" +Specifies a maximum number of lines to scroll backward. +If it is necessary to scroll backward more than \fIn\fP lines, +the screen is repainted in a forward direction instead. +(If the terminal does not have the ability to scroll +backward, \-h0 is implied.) +.IP "\-i or \-\-ignore-case" +Causes searches to ignore case; that is, +uppercase and lowercase are considered identical. +This option is ignored if any uppercase letters +appear in the search pattern; +in other words, +if a pattern contains uppercase letters, then that search does not ignore case. +.IP "\-I or \-\-IGNORE-CASE" +Like \-i, but searches ignore case even if +the pattern contains uppercase letters. +.IP "\-j\fIn\fP or \-\-jump-target=\fIn\fP" +Specifies a line on the screen where the "target" line +is to be positioned. +The target line is the line specified by any command to +search for a pattern, jump to a line number, +jump to a file percentage or jump to a tag. +The screen line may be specified by a number: the top line on the screen +is 1, the next is 2, and so on. +The number may be negative to specify a line relative to the bottom +of the screen: the bottom line on the screen is \-1, the second +to the bottom is \-2, and so on. +Alternately, the screen line may be specified as a fraction of the height +of the screen, starting with a decimal point: .5 is in the middle of the +screen, .3 is three tenths down from the first line, and so on. +If the line is specified as a fraction, the actual line number +is recalculated if the terminal window is resized, so that the +target line remains at the specified fraction of the screen height. +If any form of the \-j option is used, +forward searches begin at the line immediately after the target line, +and backward searches begin at the target line, +unless changed by \-a or \-A. +For example, if "\-j4" is used, the target line is the +fourth line on the screen, so forward searches begin at the fifth line +on the screen. +.IP "\-J or \-\-status-column" +Displays a status column at the left edge of the screen. +The status column shows the lines that matched the current search. +The status column is also used if the \-w or \-W option is in effect. +.IP "\-k\fIfilename\fP or \-\-lesskey-file=\fIfilename\fP" +Causes +.I less +to open and interpret the named file as a +.I lesskey +(1) file. +Multiple \-k options may be specified. +If the LESSKEY or LESSKEY_SYSTEM environment variable is set, or +if a lesskey file is found in a standard place (see KEY BINDINGS), +it is also used as a +.I lesskey +file. +.IP "\-K or \-\-quit-on-intr" +Causes +.I less +to exit immediately (with status 2) +when an interrupt character (usually ^C) is typed. +Normally, an interrupt character causes +.I less +to stop whatever it is doing and return to its command prompt. +Note that use of this option makes it impossible to return to the +command prompt from the "F" command. +.IP "\-L or \-\-no-lessopen" +Ignore the LESSOPEN environment variable +(see the INPUT PREPROCESSOR section below). +This option can be set from within \fIless\fP, +but it will apply only to files opened subsequently, not to the +file which is currently open. +.IP "\-m or \-\-long-prompt" +Causes +.I less +to prompt verbosely (like \fImore\fP), +with the percent into the file. +By default, +.I less +prompts with a colon. +.IP "\-M or \-\-LONG-PROMPT" +Causes +.I less +to prompt even more verbosely than +.I more. +.IP "\-n or \-\-line-numbers" +Suppresses line numbers. +The default (to use line numbers) may cause +.I less +to run more slowly in some cases, especially with a very large input file. +Suppressing line numbers with the \-n option will avoid this problem. +Using line numbers means: the line number will be displayed in the verbose +prompt and in the = command, +and the v command will pass the current line number to the editor +(see also the discussion of LESSEDIT in PROMPTS below). +.IP "\-N or \-\-LINE-NUMBERS" +Causes a line number to be displayed at the beginning of +each line in the display. +.IP "\-o\fIfilename\fP or \-\-log-file=\fIfilename\fP" +Causes +.I less +to copy its input to the named file as it is being viewed. +This applies only when the input file is a pipe, +not an ordinary file. +If the file already exists, +.I less +will ask for confirmation before overwriting it. +.IP "\-O\fIfilename\fP or \-\-LOG-FILE=\fIfilename\fP" +The \-O option is like \-o, but it will overwrite an existing +file without asking for confirmation. +.sp +If no log file has been specified, +the \-o and \-O options can be used from within +.I less +to specify a log file. +Without a file name, they will simply report the name of the log file. +The "s" command is equivalent to specifying \-o from within +.I less. +.IP "\-p\fIpattern\fP or \-\-pattern=\fIpattern\fP" +The \-p option on the command line is equivalent to +specifying +/\fIpattern\fP; +that is, it tells +.I less +to start at the first occurrence of \fIpattern\fP in the file. +.IP "\-P\fIprompt\fP or \-\-prompt=\fIprompt\fP" +Provides a way to tailor the three prompt +styles to your own preference. +This option would normally be put in the LESS environment +variable, rather than being typed in with each +.I less +command. +Such an option must either be the last option in the LESS variable, +or be terminated by a dollar sign. +-Ps followed by a string changes the default (short) prompt +to that string. +-Pm changes the medium (\-m) prompt. +-PM changes the long (\-M) prompt. +-Ph changes the prompt for the help screen. +-P= changes the message printed by the = command. +-Pw changes the message printed while waiting for data (in the F command). +All prompt strings consist of a sequence of +letters and special escape sequences. +See the section on PROMPTS for more details. +.IP "\-q or \-\-quiet or \-\-silent" +Causes moderately "quiet" operation: +the terminal bell is not rung +if an attempt is made to scroll past the end of the file +or before the beginning of the file. +If the terminal has a "visual bell", it is used instead. +The bell will be rung on certain other errors, +such as typing an invalid character. +The default is to ring the terminal bell in all such cases. +.IP "\-Q or \-\-QUIET or \-\-SILENT" +Causes totally "quiet" operation: +the terminal bell is never rung. +.IP "\-r or \-\-raw-control-chars" +Causes "raw" control characters to be displayed. +The default is to display control characters using the caret notation; +for example, a control-A (octal 001) is displayed as "^A". +Warning: when the \-r option is used, +.I less +cannot keep track of the actual appearance of the screen +(since this depends on how the screen responds to +each type of control character). +Thus, various display problems may result, +such as long lines being split in the wrong place. +.IP "\-R or \-\-RAW-CONTROL-CHARS" +Like \-r, but only ANSI "color" escape sequences are output in "raw" form. +Unlike \-r, the screen appearance is maintained correctly in most cases. +ANSI "color" escape sequences are sequences of the form: +.sp + ESC [ ... m +.sp +where the "..." is zero or more color specification characters +For the purpose of keeping track of screen appearance, +ANSI color escape sequences are assumed to not move the cursor. +You can make +.I less +think that characters other than "m" can end ANSI color escape sequences +by setting the environment variable LESSANSIENDCHARS to the list of +characters which can end a color escape sequence. +And you can make +.I less +think that characters other than the standard ones may appear between +the ESC and the m by setting the environment variable LESSANSIMIDCHARS +to the list of characters which can appear. +.IP "\-s or \-\-squeeze-blank-lines" +Causes consecutive blank lines to be squeezed into a single blank line. +This is useful when viewing +.I nroff +output. +.IP "\-S or \-\-chop-long-lines" +Causes lines longer than the screen width to be +chopped (truncated) rather than wrapped. +That is, the portion of a long line that does not fit in +the screen width is not shown. +The default is to wrap long lines; that is, display the remainder +on the next line. +.IP "\-t\fItag\fP or \-\-tag=\fItag\fP" +The \-t option, followed immediately by a TAG, +will edit the file containing that tag. +For this to work, tag information must be available; +for example, there may be a file in the current directory called "tags", +which was previously built by +.I ctags +(1) or an equivalent command. +If the environment variable LESSGLOBALTAGS is set, it is taken to be +the name of a command compatible with +.I global +(1), and that command is executed to find the tag. +(See http://www.gnu.org/software/global/global.html). +The \-t option may also be specified from within +.I less +(using the \- command) as a way of examining a new file. +The command ":t" is equivalent to specifying \-t from within +.I less. +.IP "\-T\fItagsfile\fP or \-\-tag-file=\fItagsfile\fP" +Specifies a tags file to be used instead of "tags". +.IP "\-u or \-\-underline-special" +Causes backspaces and carriage returns to be treated as printable characters; +that is, they are sent to the terminal when they appear in the input. +.IP "\-U or \-\-UNDERLINE-SPECIAL" +Causes backspaces, tabs and carriage returns to be +treated as control characters; +that is, they are handled as specified by the \-r option. +.sp +By default, if neither \-u nor \-U is given, +backspaces which appear adjacent to an underscore character +are treated specially: +the underlined text is displayed +using the terminal's hardware underlining capability. +Also, backspaces which appear between two identical characters +are treated specially: +the overstruck text is printed +using the terminal's hardware boldface capability. +Other backspaces are deleted, along with the preceding character. +Carriage returns immediately followed by a newline are deleted. +Other carriage returns are handled as specified by the \-r option. +Text which is overstruck or underlined can be searched for +if neither \-u nor \-U is in effect. +.IP "\-V or \-\-version" +Displays the version number of +.I less. +.IP "\-w or \-\-hilite-unread" +Temporarily highlights the first "new" line after a forward movement +of a full page. +The first "new" line is the line immediately following the line previously +at the bottom of the screen. +Also highlights the target line after a g or p command. +The highlight is removed at the next command which causes movement. +The entire line is highlighted, unless the \-J option is in effect, +in which case only the status column is highlighted. +.IP "\-W or \-\-HILITE-UNREAD" +Like \-w, but temporarily highlights the first new line after any +forward movement command larger than one line. +.IP "\-x\fIn\fP,... or \-\-tabs=\fIn\fP,..." +Sets tab stops. +If only one \fIn\fP is specified, tab stops are set at multiples of \fIn\fP. +If multiple values separated by commas are specified, tab stops +are set at those positions, and then continue with the same spacing as the +last two. +For example, \fI-x9,17\fP will set tabs at positions 9, 17, 25, 33, etc. +The default for \fIn\fP is 8. +.IP "\-X or \-\-no-init" +Disables sending the termcap initialization and deinitialization strings +to the terminal. +This is sometimes desirable if the deinitialization string does +something unnecessary, like clearing the screen. +.IP "\-y\fIn\fP or \-\-max-forw-scroll=\fIn\fP" +Specifies a maximum number of lines to scroll forward. +If it is necessary to scroll forward more than \fIn\fP lines, +the screen is repainted instead. +The \-c or \-C option may be used to repaint from the top of +the screen if desired. +By default, any forward movement causes scrolling. +.IP "\-[z]\fIn\fP or \-\-window=\fIn\fP" +Changes the default scrolling window size to \fIn\fP lines. +The default is one screenful. +The z and w commands can also be used to change the window size. +The "z" may be omitted for compatibility with some versions of +.I more. +If the number +.I n +is negative, it indicates +.I n +lines less than the current screen size. +For example, if the screen is 24 lines, \fI\-z-4\fP sets the +scrolling window to 20 lines. If the screen is resized to 40 lines, +the scrolling window automatically changes to 36 lines. +.IP "\-\fI\(dqcc\fP\ or\ \-\-quotes=\fIcc\fP" +Changes the filename quoting character. +This may be necessary if you are trying to name a file +which contains both spaces and quote characters. +Followed by a single character, this changes the quote character to that +character. +Filenames containing a space should then be surrounded by that character +rather than by double quotes. +Followed by two characters, changes the open quote to the first character, +and the close quote to the second character. +Filenames containing a space should then be preceded by the open quote +character and followed by the close quote character. +Note that even after the quote characters are changed, this option +remains \-" (a dash followed by a double quote). +.IP "\-~ or \-\-tilde" +Normally lines after end of file are displayed as a single tilde (~). +This option causes lines after end of file to be displayed as blank lines. +.IP "\-# or \-\-shift" +Specifies the default number of positions to scroll horizontally +in the RIGHTARROW and LEFTARROW commands. +If the number specified is zero, it sets the default number of +positions to one half of the screen width. +Alternately, the number may be specified as a fraction of the width +of the screen, starting with a decimal point: .5 is half of the +screen width, .3 is three tenths of the screen width, and so on. +If the number is specified as a fraction, the actual number of +scroll positions is recalculated if the terminal window is resized, +so that the actual scroll remains at the specified fraction +of the screen width. +.IP "\-\-no-keypad" +Disables sending the keypad initialization and deinitialization strings +to the terminal. +This is sometimes useful if the keypad strings make the numeric +keypad behave in an undesirable manner. +.IP "\-\-follow-name" +Normally, if the input file is renamed while an F command is executing, +.I less +will continue to display the contents of the original file despite +its name change. +If \-\-follow-name is specified, during an F command +.I less +will periodically attempt to reopen the file by name. +If the reopen succeeds and the file is a different file from the original +(which means that a new file has been created +with the same name as the original (now renamed) file), +.I less +will display the contents of that new file. +.IP \-\- +A command line argument of "\-\-" marks the end of option arguments. +Any arguments following this are interpreted as filenames. +This can be useful when viewing a file whose name begins with a "\-" or "+". +.IP + +If a command line option begins with \fB+\fP, +the remainder of that option is taken to be an initial command to +.I less. +For example, +G tells +.I less +to start at the end of the file rather than the beginning, +and +/xyz tells it to start at the first occurrence of "xyz" in the file. +As a special case, +<number> acts like +<number>g; +that is, it starts the display at the specified line number +(however, see the caveat under the "g" command above). +If the option starts with ++, the initial command applies to +every file being viewed, not just the first one. +The + command described previously +may also be used to set (or change) an initial command for every file. + +.SH "LINE EDITING" +When entering command line at the bottom of the screen +(for example, a filename for the :e command, +or the pattern for a search command), +certain keys can be used to manipulate the command line. +Most commands have an alternate form in [ brackets ] which can be used if +a key does not exist on a particular keyboard. +(Note that the forms beginning with ESC do not work +in some MS-DOS and Windows systems because ESC is the line erase character.) +Any of these special keys may be entered literally by preceding +it with the "literal" character, either ^V or ^A. +A backslash itself may also be entered literally by entering two backslashes. +.IP "LEFTARROW [ ESC-h ]" +Move the cursor one space to the left. +.IP "RIGHTARROW [ ESC-l ]" +Move the cursor one space to the right. +.IP "^LEFTARROW [ ESC-b or ESC-LEFTARROW ]" +(That is, CONTROL and LEFTARROW simultaneously.) +Move the cursor one word to the left. +.IP "^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]" +(That is, CONTROL and RIGHTARROW simultaneously.) +Move the cursor one word to the right. +.IP "HOME [ ESC-0 ]" +Move the cursor to the beginning of the line. +.IP "END [ ESC-$ ]" +Move the cursor to the end of the line. +.IP "BACKSPACE" +Delete the character to the left of the cursor, +or cancel the command if the command line is empty. +.IP "DELETE or [ ESC-x ]" +Delete the character under the cursor. +.IP "^BACKSPACE [ ESC-BACKSPACE ]" +(That is, CONTROL and BACKSPACE simultaneously.) +Delete the word to the left of the cursor. +.IP "^DELETE [ ESC-X or ESC-DELETE ]" +(That is, CONTROL and DELETE simultaneously.) +Delete the word under the cursor. +.IP "UPARROW [ ESC-k ]" +Retrieve the previous command line. +If you first enter some text and then press UPARROW, +it will retrieve the previous command which begins with that text. +.IP "DOWNARROW [ ESC-j ]" +Retrieve the next command line. +If you first enter some text and then press DOWNARROW, +it will retrieve the next command which begins with that text. +.IP "TAB" +Complete the partial filename to the left of the cursor. +If it matches more than one filename, the first match +is entered into the command line. +Repeated TABs will cycle thru the other matching filenames. +If the completed filename is a directory, a "/" is appended to the filename. +(On MS-DOS systems, a "\e" is appended.) +The environment variable LESSSEPARATOR can be used to specify a +different character to append to a directory name. +.IP "BACKTAB [ ESC-TAB ]" +Like, TAB, but cycles in the reverse direction thru the matching filenames. +.IP "^L" +Complete the partial filename to the left of the cursor. +If it matches more than one filename, all matches are entered into +the command line (if they fit). +.IP "^U (Unix and OS/2) or ESC (MS-DOS)" +Delete the entire command line, +or cancel the command if the command line is empty. +If you have changed your line-kill character in Unix to something +other than ^U, that character is used instead of ^U. +.IP "^G" +Delete the entire command line and return to the main prompt. + +.SH "KEY BINDINGS" +You may define your own +.I less +commands by using the program +.I lesskey +(1) +to create a lesskey file. +This file specifies a set of command keys and an action +associated with each key. +You may also use +.I lesskey +to change the line-editing keys (see LINE EDITING), +and to set environment variables. +If the environment variable LESSKEY is set, +.I less +uses that as the name of the lesskey file. +Otherwise, +.I less +looks in a standard place for the lesskey file: +On Unix systems, +.I less +looks for a lesskey file called "$HOME/.less". +On MS-DOS and Windows systems, +.I less +looks for a lesskey file called "$HOME/_less", and if it is not found there, +then looks for a lesskey file called "_less" in any directory specified +in the PATH environment variable. +On OS/2 systems, +.I less +looks for a lesskey file called "$HOME/less.ini", and if it is not found, +then looks for a lesskey file called "less.ini" in any directory specified +in the INIT environment variable, and if it not found there, +then looks for a lesskey file called "less.ini" in any directory specified +in the PATH environment variable. +See the +.I lesskey +manual page for more details. +.P +A system-wide lesskey file may also be set up to provide key bindings. +If a key is defined in both a local lesskey file and in the +system-wide file, key bindings in the local file take precedence over +those in the system-wide file. +If the environment variable LESSKEY_SYSTEM is set, +.I less +uses that as the name of the system-wide lesskey file. +Otherwise, +.I less +looks in a standard place for the system-wide lesskey file: +On Unix systems, the system-wide lesskey file is /usr/local/etc/sysless. +(However, if +.I less +was built with a different sysconf directory than /usr/local/etc, +that directory is where the sysless file is found.) +On MS-DOS and Windows systems, the system-wide lesskey file is c:\e_sysless. +On OS/2 systems, the system-wide lesskey file is c:\esysless.ini. + +.SH "INPUT PREPROCESSOR" +You may define an "input preprocessor" for +.I less. +Before +.I less +opens a file, it first gives your input preprocessor a chance to modify the +way the contents of the file are displayed. +An input preprocessor is simply an executable program (or shell script), +which writes the contents of the file to a different file, +called the replacement file. +The contents of the replacement file are then displayed +in place of the contents of the original file. +However, it will appear to the user as if the original file is opened; +that is, +.I less +will display the original filename as the name of the current file. +.PP +An input preprocessor receives one command line argument, the original filename, +as entered by the user. +It should create the replacement file, and when finished, +print the name of the replacement file to its standard output. +If the input preprocessor does not output a replacement filename, +.I less +uses the original file, as normal. +The input preprocessor is not called when viewing standard input. +To set up an input preprocessor, set the LESSOPEN environment variable +to a command line which will invoke your input preprocessor. +This command line should include one occurrence of the string "%s", +which will be replaced by the filename +when the input preprocessor command is invoked. +.PP +When +.I less +closes a file opened in such a way, it will call another program, +called the input postprocessor, +which may perform any desired clean-up action (such as deleting the +replacement file created by LESSOPEN). +This program receives two command line arguments, the original filename +as entered by the user, and the name of the replacement file. +To set up an input postprocessor, set the LESSCLOSE environment variable +to a command line which will invoke your input postprocessor. +It may include two occurrences of the string "%s"; +the first is replaced with the original name of the file and +the second with the name of the replacement file, +which was output by LESSOPEN. +.PP +For example, on many Unix systems, these two scripts will allow you +to keep files in compressed format, but still let +.I less +view them directly: +.PP +lessopen.sh: +.br + #! /bin/sh +.br + case "$1" in +.br + *.Z) uncompress -\c $1 >/tmp/less.$$ 2>/dev/null +.br + if [ \-s /tmp/less.$$ ]; then +.br + echo /tmp/less.$$ +.br + else +.br + rm \-f /tmp/less.$$ +.br + fi +.br + ;; +.br + esac +.PP +lessclose.sh: +.br + #! /bin/sh +.br + rm $2 +.PP +To use these scripts, put them both where they can be executed and +set LESSOPEN="lessopen.sh\ %s", and +LESSCLOSE="lessclose.sh\ %s\ %s". +More complex LESSOPEN and LESSCLOSE scripts may be written +to accept other types of compressed files, and so on. +.PP +It is also possible to set up an input preprocessor to +pipe the file data directly to +.I less, +rather than putting the data into a replacement file. +This avoids the need to decompress the entire file before +starting to view it. +An input preprocessor that works this way is called an input pipe. +An input pipe, instead of writing the name of a replacement file on +its standard output, +writes the entire contents of the replacement file on its standard output. +If the input pipe does not write any characters on its standard output, +then there is no replacement file and +.I less +uses the original file, as normal. +To use an input pipe, +make the first character in the LESSOPEN environment variable a +vertical bar (|) to signify that the input preprocessor is an input pipe. +.PP +For example, on many Unix systems, this script will work like the +previous example scripts: +.PP +lesspipe.sh: +.br + #! /bin/sh +.br + case "$1" in +.br + *.Z) uncompress \-c $1 2>/dev/null +.br + *) exit 1 +.br + ;; +.br + esac +.br + exit $? +.br +.PP +To use this script, put it where it can be executed and set +LESSOPEN="|lesspipe.sh %s". +.PP +Note that a preprocessor cannot output an empty file, since that +is interpreted as meaning there is no replacement, and +the original file is used. +To avoid this, if LESSOPEN starts with two vertical bars, +the exit status of the script becomes meaningful. +If the exit status is zero, the output is considered to be +replacement text, even if it empty. +If the exit status is nonzero, any output is ignored and the +original file is used. +For compatibility with previous versions of +.I less, +if LESSOPEN starts with only one vertical bar, the exit status +of the preprocessor is ignored. +.PP +When an input pipe is used, a LESSCLOSE postprocessor can be used, +but it is usually not necessary since there is no replacement file +to clean up. +In this case, the replacement file name passed to the LESSCLOSE +postprocessor is "\-". +.PP +For compatibility with previous versions of +.I less, +the input preprocessor or pipe is not used if +.I less +is viewing standard input. +However, if the first character of LESSOPEN is a dash (\-), +the input preprocessor is used on standard input as well as other files. +In this case, the dash is not considered to be part of +the preprocessor command. +If standard input is being viewed, the input preprocessor is passed +a file name consisting of a single dash. +Similarly, if the first two characters of LESSOPEN are vertical bar and dash +(|\-) or two vertical bars and a dash (||\-), +the input pipe is used on standard input as well as other files. +Again, in this case the dash is not considered to be part of +the input pipe command. + +.SH "NATIONAL CHARACTER SETS" +There are three types of characters in the input file: +.IP "normal characters" +can be displayed directly to the screen. +.IP "control characters" +should not be displayed directly, but are expected to be found +in ordinary text files (such as backspace and tab). +.IP "binary characters" +should not be displayed directly and are not expected to be found +in text files. +.PP +A "character set" is simply a description of which characters are to +be considered normal, control, and binary. +The LESSCHARSET environment variable may be used to select a character set. +Possible values for LESSCHARSET are: +.IP ascii +BS, TAB, NL, CR, and formfeed are control characters, +all chars with values between 32 and 126 are normal, +and all others are binary. +.IP iso8859 +Selects an ISO 8859 character set. +This is the same as ASCII, except characters between 160 and 255 are +treated as normal characters. +.IP latin1 +Same as iso8859. +.IP latin9 +Same as iso8859. +.IP dos +Selects a character set appropriate for MS-DOS. +.IP ebcdic +Selects an EBCDIC character set. +.IP IBM-1047 +Selects an EBCDIC character set used by OS/390 Unix Services. +This is the EBCDIC analogue of latin1. You get similar results +by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US +in your environment. +.IP koi8-r +Selects a Russian character set. +.IP next +Selects a character set appropriate for NeXT computers. +.IP utf-8 +Selects the UTF-8 encoding of the ISO 10646 character set. +UTF-8 is special in that it supports multi-byte characters in the input file. +It is the only character set that supports multi-byte characters. +.IP windows +Selects a character set appropriate for Microsoft Windows (cp 1251). +.PP +In rare cases, it may be desired to tailor +.I less +to use a character set other than the ones definable by LESSCHARSET. +In this case, the environment variable LESSCHARDEF can be used +to define a character set. +It should be set to a string where each character in the string represents +one character in the character set. +The character "." is used for a normal character, "c" for control, +and "b" for binary. +A decimal number may be used for repetition. +For example, "bccc4b." would mean character 0 is binary, +1, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8 is normal. +All characters after the last are taken to be the same as the last, +so characters 9 through 255 would be normal. +(This is an example, and does not necessarily +represent any real character set.) +.PP +This table shows the value of LESSCHARDEF which is equivalent +to each of the possible values for LESSCHARSET: +.sp + ascii\ 8bcccbcc18b95.b +.br + dos\ \ \ 8bcccbcc12bc5b95.b. +.br + ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b +.br + \ \ \ \ \ \ 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b. +.br + IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc +.br + \ \ \ \ \ \ 191.b +.br + iso8859 8bcccbcc18b95.33b. +.br + koi8-r 8bcccbcc18b95.b128. +.br + latin1 8bcccbcc18b95.33b. +.br + next\ \ 8bcccbcc18b95.bb125.bb +.PP +If neither LESSCHARSET nor LESSCHARDEF is set, +but any of the strings "UTF-8", "UTF8", "utf-8" or "utf8" +is found in the LC_ALL, LC_CTYPE or LANG +environment variables, then the default character set is utf-8. +.PP +If that string is not found, but your system supports the +.I setlocale +interface, +.I less +will use setlocale to determine the character set. +setlocale is controlled by setting the LANG or LC_CTYPE environment +variables. +.PP +Finally, if the +.I setlocale +interface is also not available, the default character set is latin1. +.PP +Control and binary characters are displayed in standout (reverse video). +Each such character is displayed in caret notation if possible +(e.g. ^A for control-A). Caret notation is used only if +inverting the 0100 bit results in a normal printable character. +Otherwise, the character is displayed as a hex number in angle brackets. +This format can be changed by +setting the LESSBINFMT environment variable. +LESSBINFMT may begin with a "*" and one character to select +the display attribute: +"*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout, +and "*n" is normal. +If LESSBINFMT does not begin with a "*", normal attribute is assumed. +The remainder of LESSBINFMT is a string which may include one +printf-style escape sequence (a % followed by x, X, o, d, etc.). +For example, if LESSBINFMT is "*u[%x]", binary characters +are displayed in underlined hexadecimal surrounded by brackets. +The default if no LESSBINFMT is specified is "*s<%02X>". +Warning: the result of expanding the character via LESSBINFMT must +be less than 31 characters. +.PP +When the character set is utf-8, the LESSUTFBINFMT environment variable +acts similarly to LESSBINFMT but it applies to Unicode code points +that were successfully decoded but are unsuitable for display (e.g., +unassigned code points). +Its default value is "<U+%04lX>". +Note that LESSUTFBINFMT and LESSBINFMT share their display attribute +setting ("*x") so specifying one will affect both; +LESSUTFBINFMT is read after LESSBINFMT so its setting, if any, +will have priority. +Problematic octets in a UTF-8 file (octets of a truncated sequence, +octets of a complete but non-shortest form sequence, illegal octets, +and stray trailing octets) +are displayed individually using LESSBINFMT so as to facilitate diagnostic +of how the UTF-8 file is ill-formed. + +.SH "PROMPTS" +The \-P option allows you to tailor the prompt to your preference. +The string given to the \-P option replaces the specified prompt string. +Certain characters in the string are interpreted specially. +The prompt mechanism is rather complicated to provide flexibility, +but the ordinary user need not understand the details of constructing +personalized prompt strings. +.sp +A percent sign followed by a single character is expanded +according to what the following character is: +.IP "%b\fIX\fP" +Replaced by the byte offset into the current input file. +The b is followed by a single character (shown as \fIX\fP above) +which specifies the line whose byte offset is to be used. +If the character is a "t", the byte offset of the top line in the +display is used, +an "m" means use the middle line, +a "b" means use the bottom line, +a "B" means use the line just after the bottom line, +and a "j" means use the "target" line, as specified by the \-j option. +.IP "%B" +Replaced by the size of the current input file. +.IP "%c" +Replaced by the column number of the text appearing in the first +column of the screen. +.IP "%d\fIX\fP" +Replaced by the page number of a line in the input file. +The line to be used is determined by the \fIX\fP, as with the %b option. +.IP "%D" +Replaced by the number of pages in the input file, +or equivalently, the page number of the last line in the input file. +.IP "%E" +Replaced by the name of the editor (from the VISUAL environment variable, +or the EDITOR environment variable if VISUAL is not defined). +See the discussion of the LESSEDIT feature below. +.IP "%f" +Replaced by the name of the current input file. +.IP "%F" +Replaced by the last component of the name of the current input file. +.IP "%i" +Replaced by the index of the current file in the list of +input files. +.IP "%l\fIX\fP" +Replaced by the line number of a line in the input file. +The line to be used is determined by the \fIX\fP, as with the %b option. +.IP "%L" +Replaced by the line number of the last line in the input file. +.IP "%m" +Replaced by the total number of input files. +.IP "%p\fIX\fP" +Replaced by the percent into the current input file, based on byte offsets. +The line used is determined by the \fIX\fP as with the %b option. +.IP "%P\fIX\fP" +Replaced by the percent into the current input file, based on line numbers. +The line used is determined by the \fIX\fP as with the %b option. +.IP "%s" +Same as %B. +.IP "%t" +Causes any trailing spaces to be removed. +Usually used at the end of the string, but may appear anywhere. +.IP "%x" +Replaced by the name of the next input file in the list. +.PP +If any item is unknown (for example, the file size if input +is a pipe), a question mark is printed instead. +.PP +The format of the prompt string can be changed +depending on certain conditions. +A question mark followed by a single character acts like an "IF": +depending on the following character, a condition is evaluated. +If the condition is true, any characters following the question mark +and condition character, up to a period, are included in the prompt. +If the condition is false, such characters are not included. +A colon appearing between the question mark and the +period can be used to establish an "ELSE": any characters between +the colon and the period are included in the string if and only if +the IF condition is false. +Condition characters (which follow a question mark) may be: +.IP "?a" +True if any characters have been included in the prompt so far. +.IP "?b\fIX\fP" +True if the byte offset of the specified line is known. +.IP "?B" +True if the size of current input file is known. +.IP "?c" +True if the text is horizontally shifted (%c is not zero). +.IP "?d\fIX\fP" +True if the page number of the specified line is known. +.IP "?e" +True if at end-of-file. +.IP "?f" +True if there is an input filename +(that is, if input is not a pipe). +.IP "?l\fIX\fP" +True if the line number of the specified line is known. +.IP "?L" +True if the line number of the last line in the file is known. +.IP "?m" +True if there is more than one input file. +.IP "?n" +True if this is the first prompt in a new input file. +.IP "?p\fIX\fP" +True if the percent into the current input file, based on byte offsets, +of the specified line is known. +.IP "?P\fIX\fP" +True if the percent into the current input file, based on line numbers, +of the specified line is known. +.IP "?s" +Same as "?B". +.IP "?x" +True if there is a next input file +(that is, if the current input file is not the last one). +.PP +Any characters other than the special ones +(question mark, colon, period, percent, and backslash) +become literally part of the prompt. +Any of the special characters may be included in the prompt literally +by preceding it with a backslash. +.PP +Some examples: +.sp +?f%f:Standard input. +.sp +This prompt prints the filename, if known; +otherwise the string "Standard input". +.sp +?f%f .?ltLine %lt:?pt%pt\e%:?btByte %bt:-... +.sp +This prompt would print the filename, if known. +The filename is followed by the line number, if known, +otherwise the percent if known, otherwise the byte offset if known. +Otherwise, a dash is printed. +Notice how each question mark has a matching period, +and how the % after the %pt +is included literally by escaping it with a backslash. +.sp +?n?f%f\ .?m(file\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x..%t +.sp +This prints the filename if this is the first prompt in a file, +followed by the "file N of N" message if there is more +than one input file. +Then, if we are at end-of-file, the string "(END)" is printed +followed by the name of the next file, if there is one. +Finally, any trailing spaces are truncated. +This is the default prompt. +For reference, here are the defaults for +the other two prompts (\-m and \-M respectively). +Each is broken into two lines here for readability only. +.nf +.sp +?n?f%f\ .?m(file\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x.: + ?pB%pB\e%:byte\ %bB?s/%s...%t +.sp +?f%f\ .?n?m(file\ %i\ of\ %m)\ ..?ltlines\ %lt-%lb?L/%L.\ : + byte\ %bB?s/%s.\ .?e(END)\ ?x-\ Next\e:\ %x.:?pB%pB\e%..%t +.sp +.fi +And here is the default message produced by the = command: +.nf +.sp +?f%f\ .?m(file\ %i\ of\ %m)\ .?ltlines\ %lt-%lb?L/%L.\ . + byte\ %bB?s/%s.\ ?e(END)\ :?pB%pB\e%..%t +.fi +.PP +The prompt expansion features are also used for another purpose: +if an environment variable LESSEDIT is defined, it is used +as the command to be executed when the v command is invoked. +The LESSEDIT string is expanded in the same way as the prompt strings. +The default value for LESSEDIT is: +.nf +.sp + %E\ ?lm+%lm.\ %f +.sp +.fi +Note that this expands to the editor name, followed by a + and the +line number, followed by the file name. +If your editor does not accept the "+linenumber" syntax, or has other +differences in invocation syntax, the LESSEDIT variable can be +changed to modify this default. + +.SH SECURITY +When the environment variable LESSSECURE is set to 1, +.I less +runs in a "secure" mode. +This means these features are disabled: +.RS +.IP "!" +the shell command +.IP "|" +the pipe command +.IP ":e" +the examine command. +.IP "v" +the editing command +.IP "s \-o" +log files +.IP "\-k" +use of lesskey files +.IP "\-t" +use of tags files +.IP " " +metacharacters in filenames, such as * +.IP " " +filename completion (TAB, ^L) +.RE +.PP +Less can also be compiled to be permanently in "secure" mode. + +.SH "COMPATIBILITY WITH MORE" +If the environment variable LESS_IS_MORE is set to 1, +or if the program is invoked via a file link named "more", +.I less +behaves (mostly) in conformance with the POSIX "more" command specification. +In this mode, less behaves differently in these ways: +.PP +The \-e option works differently. +If the \-e option is not set, +.I less +behaves as if the \-E option were set. +If the \-e option is set, +.I less +behaves as if the \-e and \-F options were set. +.PP +The \-m option works differently. +If the \-m option is not set, the medium prompt is used, +and it is prefixed with the string "--More--". +If the \-m option is set, the short prompt is used. +.PP +The \-n option acts like the \-z option. +The normal behavior of the \-n option is unavailable in this mode. +.PP +The parameter to the \-p option is taken to be a +.I less +command rather than a search pattern. +.PP +The LESS environment variable is ignored, +and the MORE environment variable is used in its place. + +.SH "ENVIRONMENT VARIABLES" +Environment variables may be specified either in the system environment +as usual, or in a +.I lesskey +(1) file. +If environment variables are defined in more than one place, +variables defined in a local lesskey file take precedence over +variables defined in the system environment, which take precedence +over variables defined in the system-wide lesskey file. +.IP COLUMNS +Sets the number of columns on the screen. +Takes precedence over the number of columns specified by the TERM variable. +(But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD, +the window system's idea of the screen size takes precedence over the +LINES and COLUMNS environment variables.) +.IP EDITOR +The name of the editor (used for the v command). +.IP HOME +Name of the user's home directory +(used to find a lesskey file on Unix and OS/2 systems). +.IP "HOMEDRIVE, HOMEPATH" +Concatenation of the HOMEDRIVE and HOMEPATH environment variables is +the name of the user's home directory if the HOME variable is not set +(only in the Windows version). +.IP INIT +Name of the user's init directory (used to find a lesskey file on OS/2 systems). +.IP LANG +Language for determining the character set. +.IP LC_CTYPE +Language for determining the character set. +.IP LESS +Options which are passed to +.I less +automatically. +.IP LESSANSIENDCHARS +Characters which may end an ANSI color escape sequence +(default "m"). +.IP LESSANSIMIDCHARS +Characters which may appear between the ESC character and the +end character in an ANSI color escape sequence +(default "0123456789;[?!"'#%()*+\ ". +.IP LESSBINFMT +Format for displaying non-printable, non-control characters. +.IP LESSCHARDEF +Defines a character set. +.IP LESSCHARSET +Selects a predefined character set. +.IP LESSCLOSE +Command line to invoke the (optional) input-postprocessor. +.IP LESSECHO +Name of the lessecho program (default "lessecho"). +The lessecho program is needed to expand metacharacters, such as * and ?, +in filenames on Unix systems. +.IP LESSEDIT +Editor prototype string (used for the v command). +See discussion under PROMPTS. +.IP LESSGLOBALTAGS +Name of the command used by the \-t option to find global tags. +Normally should be set to "global" if your system has the +.I global +(1) command. If not set, global tags are not used. +.IP LESSHISTFILE +Name of the history file used to remember search commands and +shell commands between invocations of +.I less. +If set to "\-" or "/dev/null", a history file is not used. +The default is "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on +DOS and Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini" +on OS/2 systems. +.IP LESSHISTSIZE +The maximum number of commands to save in the history file. +The default is 100. +.IP LESSKEY +Name of the default lesskey(1) file. +.IP LESSKEY_SYSTEM +Name of the default system-wide lesskey(1) file. +.IP LESSMETACHARS +List of characters which are considered "metacharacters" by the shell. +.IP LESSMETAESCAPE +Prefix which less will add before each metacharacter in a +command sent to the shell. +If LESSMETAESCAPE is an empty string, commands containing +metacharacters will not be passed to the shell. +.IP LESSOPEN +Command line to invoke the (optional) input-preprocessor. +.IP LESSSECURE +Runs less in "secure" mode. +See discussion under SECURITY. +.IP LESSSEPARATOR +String to be appended to a directory name in filename completion. +.IP LESSUTFBINFMT +Format for displaying non-printable Unicode code points. +.IP LESS_IS_MORE +Emulate the +.I more +(1) command. +.IP LINES +Sets the number of lines on the screen. +Takes precedence over the number of lines specified by the TERM variable. +(But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD, +the window system's idea of the screen size takes precedence over the +LINES and COLUMNS environment variables.) +.IP MORE +Options which are passed to +.I less +automatically when running in +.I more +compatible mode. +.IP PATH +User's search path (used to find a lesskey file +on MS-DOS and OS/2 systems). +.IP SHELL +The shell used to execute the ! command, as well as to expand filenames. +.IP TERM +The type of terminal on which +.I less +is being run. +.IP VISUAL +The name of the editor (used for the v command). + +.SH "SEE ALSO" +lesskey(1) + +.SH COPYRIGHT +Copyright (C) 1984-2012 Mark Nudelman +.PP +less is part of the GNU project and is free software. +You can redistribute it and/or modify it +under the terms of either +(1) the GNU General Public License as published by +the Free Software Foundation; or (2) the Less License. +See the file README in the less distribution for more details +regarding redistribution. +You should have received a copy of the GNU General Public License +along with the source for less; see the file COPYING. +If not, write to the Free Software Foundation, 59 Temple Place, +Suite 330, Boston, MA 02111-1307, USA. +You should also have received a copy of the Less License; +see the file LICENSE. +.PP +less is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +or FITNESS FOR A PARTICULAR PURPOSE. +See the GNU General Public License for more details. + +.SH AUTHOR +.PP +Mark Nudelman <bug-less@gnu.org> +.br +Send bug reports or comments to bug-less@gnu.org. +.br +See http://www.greenwoodsoftware.com/less/bugs.html for the latest list of known bugs in less. +.br +For more information, see the less homepage at +.br +http://www.greenwoodsoftware.com/less. |