2090 lines
77 KiB
Plaintext
2090 lines
77 KiB
Plaintext
'\" t
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.TH LESS 1 "Version 608: 22 Jul 2022"
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.SH NAME
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less \- opposite of more
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.SH SYNOPSIS
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.B "less \-?"
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.br
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.B "less \-\-help"
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.br
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.B "less \-V"
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.br
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.B "less \-\-version"
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.br
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.B "less [\-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]"
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.br
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.B " [\-b \fIspace\/\fP] [\-h \fIlines\/\fP] [\-j \fIline\/\fP] [\-k \fIkeyfile\/\fP]"
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.br
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.B " [\-{oO} \fIlogfile\/\fP] [\-p \fIpattern\/\fP] [\-P \fIprompt\/\fP] [\-t \fItag\/\fP]"
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.br
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.B " [\-T \fItagsfile\/\fP] [\-x \fItab\/\fP,...] [\-y \fIlines\/\fP] [\-[z] \fIlines\/\fP]"
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.br
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.B " [\-# \fIshift\/\fP] [+[+]\fIcmd\/\fP] [\-\-] [\fIfilename\/\fP]..."
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.br
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(See the OPTIONS section for alternate option syntax with long option names.)
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.
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.SH DESCRIPTION
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.I Less
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is a program similar to
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.IR more (1),
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but which allows backward movement
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in the file as well as forward movement.
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Also,
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.I less
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does not have to read the entire input file before starting,
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so with large input files it starts up faster than text editors like
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.IR vi (1).
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.I Less
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uses termcap (or terminfo on some systems),
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so it can run on a variety of terminals.
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There is even limited support for hardcopy terminals.
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(On a hardcopy terminal, lines which should be printed at the top
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of the screen are prefixed with a caret.)
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.PP
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Commands are based on both
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.I more
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and
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.IR vi .
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Commands may be preceded by a decimal number,
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called N in the descriptions below.
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The number is used by some commands, as indicated.
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.
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.SH COMMANDS
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In the following descriptions, ^X means control-X.
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ESC stands for the ESCAPE key; for example ESC-v means the
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two character sequence "ESCAPE", then "v".
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.IP "h or H"
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Help: display a summary of these commands.
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If you forget all the other commands, remember this one.
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.IP "SPACE or ^V or f or ^F"
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Scroll forward N lines, default one window (see option \-z below).
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If N is more than the screen size, only the final screenful is displayed.
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Warning: some systems use ^V as a special literalization character.
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.IP "z"
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Like SPACE, but if N is specified, it becomes the new window size.
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.IP "ESC-SPACE"
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Like SPACE, but scrolls a full screenful, even if it reaches
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end-of-file in the process.
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.IP "ENTER or RETURN or ^N or e or ^E or j or ^J"
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Scroll forward N lines, default 1.
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The entire N lines are displayed, even if N is more than the screen size.
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.IP "d or ^D"
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Scroll forward N lines, default one half of the screen size.
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If N is specified, it becomes the new default for
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subsequent d and u commands.
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.IP "b or ^B or ESC-v"
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Scroll backward N lines, default one window (see option \-z below).
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If N is more than the screen size, only the final screenful is displayed.
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.IP "w"
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Like ESC-v, but if N is specified, it becomes the new window size.
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.IP "y or ^Y or ^P or k or ^K"
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Scroll backward N lines, default 1.
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The entire N lines are displayed, even if N is more than the screen size.
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Warning: some systems use ^Y as a special job control character.
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.IP "u or ^U"
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Scroll backward N lines, default one half of the screen size.
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If N is specified, it becomes the new default for
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subsequent d and u commands.
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.IP "J"
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Like j, but continues to scroll beyond the end of the file.
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.IP "K or Y"
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Like k, but continues to scroll beyond the beginning of the file.
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.IP "ESC-) or RIGHTARROW"
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Scroll horizontally right N characters, default half the screen width
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(see the \-# option).
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If a number N is specified, it becomes the default for future RIGHTARROW
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and LEFTARROW commands.
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While the text is scrolled, it acts as though the \-S option
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(chop lines) were in effect.
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.IP "ESC-( or LEFTARROW"
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Scroll horizontally left N characters, default half the screen width
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(see the \-# option).
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If a number N is specified, it becomes the default for future RIGHTARROW
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and LEFTARROW commands.
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.IP "ESC-} or ^RIGHTARROW"
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Scroll horizontally right to show the end of the longest displayed line.
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.IP "ESC-{ or ^LEFTARROW"
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Scroll horizontally left back to the first column.
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.IP "r or ^R or ^L"
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Repaint the screen.
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.IP R
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Repaint the screen, discarding any buffered input.
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That is, reload the current file.
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Useful if the file is changing while it is being viewed.
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.IP "F"
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Scroll forward, and keep trying to read when the
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end of file is reached.
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Normally this command would be used when already at the end of the file.
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It is a way to monitor the tail of a file which is growing
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while it is being viewed.
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(The behavior is similar to the "tail \-f" command.)
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To stop waiting for more data, enter the interrupt character (usually ^C).
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On some systems you can also use ^X.
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If the input is a pipe and the \-\-exit-follow-on-close option is in effect,
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.I less
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will automatically stop waiting for data when the input side
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of the pipe is closed.
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.IP "ESC-F"
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Like F, but as soon as a line is found which matches
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the last search pattern, the terminal bell is rung
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and forward scrolling stops.
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.IP "g or < or ESC-<"
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Go to line N in the file, default 1 (beginning of file).
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(Warning: this may be slow if N is large.)
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.IP "G or > or ESC->"
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Go to line N in the file, default the end of the file.
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(Warning: this may be slow if N is large,
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or if N is not specified and
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standard input, rather than a file, is being read.)
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.IP "ESC-G"
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Same as G, except if no number N is specified and the input is standard input,
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goes to the last line which is currently buffered.
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.IP "p or %"
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Go to a position N percent into the file.
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N should be between 0 and 100, and may contain a decimal point.
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.IP "P"
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Go to the line containing byte offset N in the file.
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.IP "{"
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If a left curly bracket appears in the top line displayed
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on the screen,
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the { command will go to the matching right curly bracket.
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The matching right curly bracket is positioned on the bottom
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line of the screen.
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If there is more than one left curly bracket on the top line,
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a number N may be used to specify the N-th bracket on the line.
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.IP "}"
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If a right curly bracket appears in the bottom line displayed
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on the screen,
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the } command will go to the matching left curly bracket.
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The matching left curly bracket is positioned on the top
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line of the screen.
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If there is more than one right curly bracket on the bottom line,
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a number N may be used to specify the N-th bracket on the line.
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.IP "("
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Like {, but applies to parentheses rather than curly brackets.
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.IP ")"
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Like }, but applies to parentheses rather than curly brackets.
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.IP "["
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Like {, but applies to square brackets rather than curly brackets.
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.IP "]"
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Like }, but applies to square brackets rather than curly brackets.
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.IP "ESC-^F"
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Followed by two characters,
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acts like {, but uses the two characters as open and close brackets,
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respectively.
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For example, "ESC ^F < >" could be used to
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go forward to the > which matches the < in the top displayed line.
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.IP "ESC-^B"
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Followed by two characters,
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acts like }, but uses the two characters as open and close brackets,
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respectively.
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For example, "ESC ^B < >" could be used to
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go backward to the < which matches the > in the bottom displayed line.
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.IP m
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Followed by any lowercase or uppercase letter,
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marks the first displayed line with that letter.
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If the status column is enabled via the \-J option,
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the status column shows the marked line.
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.IP M
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Acts like m, except the last displayed line is marked
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rather than the first displayed line.
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.IP "'"
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(Single quote.)
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Followed by any lowercase or uppercase letter, returns to the position which
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was previously marked with that letter.
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Followed by another single quote, returns to the position at
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which the last "large" movement command was executed.
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Followed by a ^ or $, jumps to the beginning or end of the
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file respectively.
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Marks are preserved when a new file is examined,
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so the ' command can be used to switch between input files.
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.IP "^X^X"
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Same as single quote.
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.IP "ESC-m"
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Followed by any lowercase or uppercase letter,
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clears the mark identified by that letter.
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.IP /pattern
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Search forward in the file for the N-th line containing the pattern.
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N defaults to 1.
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The pattern is a regular expression, as recognized by
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the regular expression library supplied by your system.
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The search starts at the first line displayed
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(but see the \-a and \-j options, which change this).
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.sp
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Certain characters are special
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if entered at the beginning of the pattern;
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they modify the type of search rather than become part of the pattern:
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.RS
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.IP "^N or !"
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Search for lines which do NOT match the pattern.
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.IP "^E or *"
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Search multiple files.
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That is, if the search reaches the END of the current file
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without finding a match,
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the search continues in the next file in the command line list.
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.IP "^F or @"
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Begin the search at the first line of the FIRST file
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in the command line list,
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regardless of what is currently displayed on the screen
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or the settings of the \-a or \-j options.
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.IP "^K"
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Highlight any text which matches the pattern on the current screen,
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but don't move to the first match (KEEP current position).
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.IP "^R"
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Don't interpret regular expression metacharacters;
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that is, do a simple textual comparison.
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.IP "^W"
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WRAP around the current file.
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That is, if the search reaches the end of the current file
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without finding a match, the search continues from the first line of the
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current file up to the line where it started.
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If the ^W modifier is set, the ^E modifier is ignored.
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.RE
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.IP ?pattern
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Search backward in the file for the N-th line containing the pattern.
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The search starts at the last line displayed
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(but see the \-a and \-j options, which change this).
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.sp
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Certain characters are special as in the / command:
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.RS
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.IP "^N or !"
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Search for lines which do NOT match the pattern.
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.IP "^E or *"
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Search multiple files.
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That is, if the search reaches the beginning of the current file
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without finding a match,
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the search continues in the previous file in the command line list.
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.IP "^F or @"
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Begin the search at the last line of the last file
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in the command line list,
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regardless of what is currently displayed on the screen
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or the settings of the \-a or \-j options.
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.IP "^K"
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As in forward searches.
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.IP "^R"
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As in forward searches.
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.IP "^W"
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WRAP around the current file.
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That is, if the search reaches the beginning of the current file
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without finding a match, the search continues from the last line of the
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current file up to the line where it started.
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.RE
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.IP "ESC-/pattern"
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Same as "/*".
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.IP "ESC-?pattern"
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Same as "?*".
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.IP n
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Repeat previous search, for N-th line containing the last pattern.
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If the previous search was modified by ^N, the search is made for the
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N-th line NOT containing the pattern.
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If the previous search was modified by ^E, the search continues
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in the next (or previous) file if not satisfied in the current file.
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If the previous search was modified by ^R, the search is done
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without using regular expressions.
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There is no effect if the previous search was modified by ^F or ^K.
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.IP N
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Repeat previous search, but in the reverse direction.
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.IP "ESC-n"
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Repeat previous search, but crossing file boundaries.
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The effect is as if the previous search were modified by *.
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.IP "ESC-N"
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Repeat previous search, but in the reverse direction
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and crossing file boundaries.
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.IP "ESC-u"
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Undo search highlighting.
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Turn off highlighting of strings matching the current search pattern.
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If highlighting is already off because of a previous ESC-u command,
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turn highlighting back on.
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Any search command will also turn highlighting back on.
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(Highlighting can also be disabled by toggling the \-G option;
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in that case search commands do not turn highlighting back on.)
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.IP "ESC-U"
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Like ESC-u but also clears the saved search pattern.
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If the status column is enabled via the \-J option,
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this clears all search matches marked in the status column.
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.IP "&pattern"
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Display only lines which match the pattern;
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lines which do not match the pattern are not displayed.
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If pattern is empty (if you type & immediately followed by ENTER),
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any filtering is turned off, and all lines are displayed.
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While filtering is in effect, an ampersand is displayed at the
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beginning of the prompt,
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as a reminder that some lines in the file may be hidden.
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Multiple & commands may be entered, in which case only lines
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which match all of the patterns will be displayed.
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.sp
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Certain characters are special as in the / command:
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.RS
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.IP "^N or !"
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Display only lines which do NOT match the pattern.
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.IP "^R"
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Don't interpret regular expression metacharacters;
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that is, do a simple textual comparison.
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.RE
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.IP ":e [filename]"
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Examine a new file.
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If the filename is missing, the "current" file (see the :n and :p commands
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below) from the list of files in the command line is re-examined.
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A percent sign (%) in the filename is replaced by the name of the
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current file.
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A pound sign (#) is replaced by the name of the previously examined file.
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However, two consecutive percent signs are simply
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replaced with a single percent sign.
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This allows you to enter a filename that contains a percent sign
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in the name.
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Similarly, two consecutive pound signs are replaced with a single pound sign.
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The filename is inserted into the command line list of files
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so that it can be seen by subsequent :n and :p commands.
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If the filename consists of several files, they are all inserted into
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the list of files and the first one is examined.
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If the filename contains one or more spaces,
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the entire filename should be enclosed in double quotes
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(also see the \-" option).
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.IP "^X^V or E"
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Same as :e.
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Warning: some systems use ^V as a special literalization character.
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On such systems, you may not be able to use ^V.
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.IP ":n"
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Examine the next file (from the list of files given in the command line).
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If a number N is specified, the N-th next file is examined.
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.IP ":p"
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Examine the previous file in the command line list.
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If a number N is specified, the N-th previous file is examined.
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.IP ":x"
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Examine the first file in the command line list.
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If a number N is specified, the N-th file in the list is examined.
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.IP ":d"
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Remove the current file from the list of files.
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.IP "t"
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Go to the next tag, if there were more than one matches for the current tag.
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See the \-t option for more details about tags.
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.IP "T"
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Go to the previous tag, if there were more than one matches for the current tag.
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.IP "= or ^G or :f"
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Prints some information about the file being viewed,
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including its name
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and the line number and byte offset of the bottom line being displayed.
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If possible, it also prints the length of the file,
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the number of lines in the file
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and the percent of the file above the last displayed line.
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.IP \-
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Followed by one of the command line option letters (see OPTIONS below),
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this will change the setting of that option
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and print a message describing the new setting.
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If a ^P (CONTROL-P) is entered immediately after the dash,
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the setting of the option is changed but no message is printed.
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If the option letter has a numeric value (such as \-b or \-h),
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or a string value (such as \-P or \-t),
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a new value may be entered after the option letter.
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If no new value is entered, a message describing
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the current setting is printed and nothing is changed.
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.IP \-\-
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Like the \- command, but takes a long option name (see OPTIONS below)
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rather than a single option letter.
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You must press ENTER or RETURN after typing the option name.
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A ^P immediately after the second dash suppresses printing of a
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message describing the new setting, as in the \- command.
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.IP \-+
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Followed by one of the command line option letters
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this will reset the option to its default setting
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and print a message describing the new setting.
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(The "\-+\fIX\fP" command does the same thing
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as "\-+\fIX\fP" on the command line.)
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This does not work for string-valued options.
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.IP \-\-+
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Like the \-+ command, but takes a long option name
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rather than a single option letter.
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.IP \-!
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Followed by one of the command line option letters,
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this will reset the option to the "opposite" of its default setting
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and print a message describing the new setting.
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This does not work for numeric or string-valued options.
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.IP \-\-!
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Like the \-!\& command, but takes a long option name
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rather than a single option letter.
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.IP _
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(Underscore.)
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Followed by one of the command line option letters,
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this will print a message describing the current setting of that option.
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The setting of the option is not changed.
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.IP __
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(Double underscore.)
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Like the _ (underscore) command, but takes a long option name
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rather than a single option letter.
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You must press ENTER or RETURN after typing the option name.
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.IP +cmd
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Causes the specified cmd to be executed each time a new file is examined.
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For example, +G causes
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.I less
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|
to initially display each file starting at the end
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rather than the beginning.
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|
.IP V
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Prints the version number of
|
|
.I less
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|
being run.
|
|
.IP "q or Q or :q or :Q or ZZ"
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Exits
|
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.IR less .
|
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.PP
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|
The following
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four
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commands may or may not be valid, depending on your particular installation.
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.
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.IP v
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Invokes an editor to edit the current file being viewed.
|
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The editor is taken from the environment variable VISUAL if defined,
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or EDITOR if VISUAL is not defined,
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or defaults to "vi" if neither VISUAL nor EDITOR is defined.
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See also the discussion of LESSEDIT under the section on PROMPTS below.
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.IP "! shell-command"
|
|
Invokes a shell to run the shell-command given.
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|
A percent sign (%) in the command is replaced by the name of the
|
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current file.
|
|
A pound sign (#) is replaced by the name of the previously examined file.
|
|
"!!" repeats the last shell command.
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"!" with no shell command simply invokes a shell.
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On Unix systems, the shell is taken from the environment variable SHELL,
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or defaults to "sh".
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On MS-DOS and OS/2 systems, the shell is the normal command processor.
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.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 position marked by
|
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the letter and the current screen.
|
|
The entire current screen is included, regardless of whether the
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marked position is before or after the current screen.
|
|
<m> may also be ^ or $ to indicate beginning or end of file respectively.
|
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If <m> is \&.\& or newline, the current screen is piped.
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|
.IP "s filename"
|
|
Save the input to a file.
|
|
This only works if the input is a pipe, not an ordinary file.
|
|
.
|
|
.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
|
|
.IR csh :
|
|
.sp
|
|
setenv LESS "\-options"
|
|
.sp
|
|
or if you use
|
|
.IR 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
|
|
Some options like \-k or \-D require a string to follow the option letter.
|
|
The string for that option is considered to end when a dollar sign ($) is found.
|
|
For example, you can set two \-D options on MS-DOS like this:
|
|
.sp
|
|
LESS="Dn9.1$Ds4.1"
|
|
.sp
|
|
If the \-\-use-backslash option appears earlier in the options, then
|
|
a dollar sign or backslash may be included literally in an option string
|
|
by preceding it with a backslash.
|
|
If the \-\-use-backslash option is not in effect, then backslashes are
|
|
not treated specially, and there is no way to include a dollar sign
|
|
in the option string.
|
|
.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 64\ KB 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 64\ KB
|
|
(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
|
|
.IR 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"
|
|
Changes the color of different parts of the displayed text.
|
|
\fBx\fP is a single character which selects the type of text
|
|
whose color is being set:
|
|
.RS
|
|
.IP "B"
|
|
Binary characters.
|
|
.IP "C"
|
|
Control characters.
|
|
.IP "E"
|
|
Errors and informational messages.
|
|
.IP "H"
|
|
Header lines and columns, set via the \-\-header option.
|
|
.IP "M"
|
|
Mark letters in the status column.
|
|
.IP "N"
|
|
Line numbers enabled via the \-N option.
|
|
.IP "P"
|
|
Prompts.
|
|
.IP "R"
|
|
The rscroll character.
|
|
.IP "S"
|
|
Search results.
|
|
.IP "W"
|
|
The highlight enabled via the \-w option.
|
|
.IP "d"
|
|
Bold text.
|
|
.IP "k"
|
|
Blinking text.
|
|
.IP "s"
|
|
Standout text.
|
|
.IP "u"
|
|
Underlined text.
|
|
.RE
|
|
|
|
.RS
|
|
The uppercase letters can be used only when the \-\-use-color option is enabled.
|
|
When text color is specified by both an uppercase letter and a lowercase letter,
|
|
the uppercase letter takes precedence.
|
|
For example, error messages are normally displayed as standout text.
|
|
So if both "s" and "E" are given a color, the "E" color applies
|
|
to error messages, and the "s" color applies to other standout text.
|
|
The "d" and "u" letters refer to bold and underline text formed by
|
|
overstriking with backspaces (see the \-u option),
|
|
not to text using ANSI escape sequences with the \-R option.
|
|
.PP
|
|
A lowercase letter may be followed by a + to indicate that
|
|
the normal format change and the specified color should both be used.
|
|
For example, \-Dug displays underlined text as green without underlining;
|
|
the green color has replaced the usual underline formatting.
|
|
But \-Du+g displays underlined text as both green and in underlined format.
|
|
.PP
|
|
\fIcolor\fP is either a 4-bit color string or an 8-bit color string:
|
|
.PP
|
|
A 4-bit color string is zero, one or two characters, where
|
|
the first character specifies the foreground color and
|
|
the second specifies the background color as follows:
|
|
.IP "b"
|
|
Blue
|
|
.IP "c"
|
|
Cyan
|
|
.IP "g"
|
|
Green
|
|
.IP "k"
|
|
Black
|
|
.IP "m"
|
|
Magenta
|
|
.IP "r"
|
|
Red
|
|
.IP "w"
|
|
White
|
|
.IP "y"
|
|
Yellow
|
|
.PP
|
|
The corresponding upper-case letter denotes a brighter shade of the color.
|
|
For example, \-DNGk displays line numbers as bright green text on a black
|
|
background, and \-DEbR displays error messages as blue text on a
|
|
bright red background.
|
|
If either character is a "-" or is omitted, the corresponding color
|
|
is set to that of normal text.
|
|
.PP
|
|
An 8-bit color string is one or two decimal integers separated by a dot,
|
|
where the first integer specifies the foreground color and
|
|
the second specifies the background color.
|
|
Each integer is a value between 0 and 255 inclusive which selects
|
|
a "CSI 38;5" color value (see
|
|
.br
|
|
.nh
|
|
https://en.wikipedia.org/wiki/ANSI_escape_code#SGR)
|
|
.hy
|
|
If either integer is a "-" or is omitted,
|
|
the corresponding color is set to that of normal text.
|
|
On MS-DOS versions of
|
|
.IR less ,
|
|
8-bit color is not supported; instead, decimal values are interpreted as 4-bit
|
|
CHAR_INFO.Attributes values
|
|
(see
|
|
.br
|
|
.nh
|
|
https://docs.microsoft.com/en-us/windows/console/char-info-str).
|
|
.hy
|
|
.RE
|
|
.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,
|
|
repeated forward searches (invoked with "n" or "N")
|
|
begin at the line immediately after the target line,
|
|
and repeated 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.
|
|
However nonrepeated searches (invoked with "/" or "?")
|
|
always begin at the start or end of the current screen respectively.
|
|
.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,
|
|
and any lines that are marked (via the m or M command).
|
|
.IP "\-k\fIfilename\fP or \-\-lesskey-file=\fIfilename\fP"
|
|
Causes
|
|
.I less
|
|
to open and interpret the named file as a
|
|
.IR lesskey (1)
|
|
binary 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 "\-\-lesskey-src=\fIfilename\fP"
|
|
Causes
|
|
.I less
|
|
to open and interpret the named file as a
|
|
.IR lesskey (1)
|
|
source file.
|
|
If the LESSKEYIN or LESSKEYIN_SYSTEM environment variable is set, or
|
|
if a lesskey source file is found in a standard place (see KEY BINDINGS),
|
|
it is also used as a
|
|
.I "lesskey source"
|
|
file.
|
|
Prior to version 582, the
|
|
.I lesskey
|
|
program needed to be run to convert a
|
|
.I "lesskey source"
|
|
file to a
|
|
.I "lesskey binary"
|
|
file for
|
|
.I less
|
|
to use.
|
|
Newer versions of
|
|
.I less
|
|
read the
|
|
.I "lesskey source"
|
|
file directly and ignore the binary file if the source file exists.
|
|
.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
|
|
.IR less ,
|
|
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
|
|
.IR 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
|
|
.IR 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).
|
|
.sp 1
|
|
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.
|
|
If the terminal has a "visual bell", it is used in all cases
|
|
where the terminal bell would have been 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.
|
|
.sp
|
|
USE OF THE \-r OPTION IS NOT RECOMMENDED.
|
|
.IP "\-R or \-\-RAW-CONTROL-CHARS"
|
|
Like \-r, but only ANSI "color" escape sequences and OSC 8 hyperlink
|
|
sequences are output in "raw" form.
|
|
Unlike \-r, the screen appearance is maintained correctly,
|
|
provided that there are no escape sequences in the file
|
|
other than these types of escape sequences.
|
|
Color escape sequences are only supported when the color
|
|
is changed within one line, not across lines.
|
|
In other words, the beginning of each line is assumed to be
|
|
normal (non-colored), regardless of any escape sequences in previous lines.
|
|
For the purpose of keeping track of screen appearance,
|
|
these escape sequences are assumed to not move the cursor.
|
|
.sp
|
|
OSC 8 hyperlinks are sequences of the form:
|
|
.sp
|
|
ESC ] 8 ; \&...\& \\7
|
|
.sp
|
|
The terminating sequence may be either a BEL character (\\7)
|
|
or the two-character sequence "ESC \\".
|
|
.sp
|
|
ANSI color escape sequences are sequences of the form:
|
|
.sp
|
|
ESC [ \&...\& m
|
|
.sp
|
|
where the "...\&" is zero or more color specification characters.
|
|
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 displayed until you press RIGHT-ARROW.
|
|
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
|
|
.IR 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
|
|
.IR global (1),
|
|
and that command is executed to find the tag.
|
|
(See
|
|
.nh
|
|
http://www.gnu.org/software/global/global.html).
|
|
.hy
|
|
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
|
|
.IR 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, carriage returns and "formatting characters"
|
|
(as defined by Unicode) 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.
|
|
Unicode formatting characters, such as the Byte Order Mark,
|
|
are sent to the terminal.
|
|
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
|
|
.IR 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.
|
|
If the \-\-status-line option is in effect, the entire line
|
|
(the width of the screen) is highlighted.
|
|
Otherwise, only the text in the 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 or \-\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
|
|
.IR 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 "\-\(dq\fIcc\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 "\-\-exit-follow-on-close"
|
|
When using the "F" command on a pipe,
|
|
.I less
|
|
will automatically stop waiting for more data when the input side of the
|
|
pipe is closed.
|
|
.IP "\-\-file-size"
|
|
If \-\-file-size is specified,
|
|
.I less
|
|
will determine the size of the file
|
|
immediately after opening the file.
|
|
Normally this is not done, because it can be slow if the input file
|
|
is non-seekable (such as a pipe) and is large.
|
|
.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 "\-\-header"
|
|
Sets the number of header lines and columns displayed on the screen.
|
|
The value may be of the form "N,M" where N and M are integers,
|
|
to set the header lines to N and the header columns to M,
|
|
or it may be a single integer "N" which sets the header lines to N
|
|
and the header columns to zero.
|
|
When N is nonzero, the first N lines at the top
|
|
of the screen are replaced with the first N lines of the file,
|
|
regardless of what part of the file are being viewed.
|
|
When M is nonzero, the characters displayed at the
|
|
beginning of each line are replaced with the first M characters of the line,
|
|
even if the rest of the line is scrolled horizontally.
|
|
If either N or M is zero,
|
|
.I less
|
|
stops displaying header lines or columns, respectively.
|
|
(Note that it may be necessary to change the setting of the \-j option
|
|
to ensure that the target line is not obscured by the header line(s).)
|
|
.IP "\-\-incsearch"
|
|
Subsequent search commands will be "incremental"; that is,
|
|
.I less
|
|
will advance to the next line containing the search pattern
|
|
as each character of the pattern is typed in.
|
|
.IP "\-\-line-num-width"
|
|
Sets the minimum width of the line number field when the \-N option is in effect.
|
|
The default is 7 characters.
|
|
.IP "\-\-mouse"
|
|
Enables mouse input:
|
|
scrolling the mouse wheel down moves forward in the file,
|
|
scrolling the mouse wheel up moves backwards in the file,
|
|
and clicking the mouse sets the "#" mark to the line
|
|
where the mouse is clicked.
|
|
The number of lines to scroll when the wheel is moved
|
|
can be set by the \-\-wheel-lines option.
|
|
Mouse input works only on terminals which support X11 mouse reporting,
|
|
and on the Windows version of
|
|
.IR less .
|
|
.IP "\-\-MOUSE"
|
|
Like \-\-mouse, except the direction scrolled
|
|
on mouse wheel movement is reversed.
|
|
.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 "\-\-no-histdups"
|
|
This option changes the behavior so that if a search string or
|
|
file name is typed in, and the same string is already in the history list,
|
|
the existing copy is removed from the history list before the new one is added.
|
|
Thus, a given string will appear only once in the history list.
|
|
Normally, a string may appear multiple times.
|
|
.IP "\-\-no-number-headers"
|
|
Header lines (defined via the \-\-header option) are not assigned line numbers.
|
|
Line number 1 is assigned to the first line after any header lines.
|
|
.IP "\-\-rscroll"
|
|
This option changes the character used to mark truncated lines.
|
|
It may begin with a two-character attribute indicator like LESSBINFMT does.
|
|
If there is no attribute indicator, standout is used.
|
|
If set to "\-", truncated lines are not marked.
|
|
.IP "\-\-redraw-on-quit"
|
|
When quitting, after sending the terminal deinitialization string,
|
|
redraws the entire last screen.
|
|
On terminals whose terminal deinitialization string causes the
|
|
terminal to switch from an alternate screen,
|
|
this makes the last screenful of the current file remain visible after
|
|
.I less
|
|
has quit.
|
|
.IP "\-\-save-marks"
|
|
Save marks in the history file, so marks are retained
|
|
across different invocations of
|
|
.IR less .
|
|
.IP "\-\-search-options"
|
|
Sets default search modifiers.
|
|
The value is a string of one or more of the characters
|
|
E, F, K, N, R or W.
|
|
Setting any of these has the same effect as typing that
|
|
control character at the beginning of every search pattern.
|
|
For example, setting \-\-search-options=W is the same as
|
|
typing ^W at the beginning of every pattern.
|
|
The value "-" disables all default search modifiers.
|
|
.IP "\-\-status-col-width"
|
|
Sets the width of the status column when the \-J option is in effect.
|
|
The default is 2 characters.
|
|
.IP "\-\-status-line"
|
|
If a line is marked, the entire line (rather than just the status column)
|
|
is highlighted.
|
|
Also lines highlighted due to the \-w option will have
|
|
the entire line highlighted.
|
|
If \-\-use-color is set, the line is colored rather than highlighted.
|
|
.IP "\-\-use-backslash"
|
|
This option changes the interpretations of options which follow this one.
|
|
After the \-\-use-backslash option, any backslash in an option string is
|
|
removed and the following character is taken literally.
|
|
This allows a dollar sign to be included in option strings.
|
|
.IP "\-\-use-color"
|
|
Enables colored text in various places.
|
|
The \-D option can be used to change the colors.
|
|
Colored text works only if the terminal supports
|
|
ANSI color escape sequences (as defined in ECMA-48 SGR;
|
|
see
|
|
.br
|
|
.nh
|
|
https://www.ecma-international.org/publications-and-standards/standards/ecma-48).
|
|
.hy
|
|
.IP "\-\-wheel-lines=\fIn\fP"
|
|
Set the number of lines to scroll when the mouse wheel is scrolled
|
|
and the \-\-mouse or \-\-MOUSE option is in effect.
|
|
The default is 1 line.
|
|
.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
|
|
.IR 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 a 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 creating a lesskey source file.
|
|
This file specifies a set of command keys and an action
|
|
associated with each key.
|
|
You may also change the line-editing keys (see LINE EDITING),
|
|
and to set environment variables.
|
|
If the environment variable LESSKEYIN is set,
|
|
.I less
|
|
uses that as the name of the lesskey source file.
|
|
Otherwise,
|
|
.I less
|
|
looks in a standard place for the lesskey source file:
|
|
On Unix systems,
|
|
.I less
|
|
looks for a lesskey file called "$XDG_CONFIG_HOME/lesskey" or "$HOME/.config/lesskey" or "$HOME/.lesskey".
|
|
On MS-DOS and Windows systems,
|
|
.I less
|
|
looks for a lesskey file called "$HOME/_lesskey", and if it is not found there,
|
|
then looks for a lesskey file called "_lesskey" in any directory specified
|
|
in the PATH environment variable.
|
|
On OS/2 systems,
|
|
.I less
|
|
looks for a lesskey file called "$HOME/lesskey.ini", and if it is not found,
|
|
then looks for a lesskey file called "lesskey.ini" in any directory specified
|
|
in the INIT environment variable, and if it not found there,
|
|
then looks for a lesskey file called "lesskey.ini" in any directory specified
|
|
in the PATH environment variable.
|
|
See the
|
|
.I lesskey
|
|
manual page for more details.
|
|
.PP
|
|
A system-wide lesskey source 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 LESSKEYIN_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/syslesskey.
|
|
(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_syslesskey.
|
|
On OS/2 systems, the system-wide lesskey file is c:\esyslesskey.ini.
|
|
.PP
|
|
Previous versions of
|
|
.I less
|
|
(before v582) used lesskey files with a binary format, produced by the
|
|
.I lesskey
|
|
program. It is no longer necessary to use the
|
|
.I lesskey
|
|
program.
|
|
.
|
|
.SH "INPUT PREPROCESSOR"
|
|
You may define an "input preprocessor" for
|
|
.IR 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 "$1" in
|
|
.br
|
|
*.Z) TEMPFILE=$(mktemp)
|
|
.br
|
|
uncompress \-c $1 >$TEMPFILE 2>/dev/null
|
|
.br
|
|
if [ \-s $TEMPFILE ]; then
|
|
.br
|
|
echo $TEMPFILE
|
|
.br
|
|
else
|
|
.br
|
|
rm \-f $TEMPFILE
|
|
.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
|
|
.IR 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.
|
|
As with non-pipe input preprocessors, the command string must contain one
|
|
occurrence of %s, which is replaced with the filename of the input file.
|
|
.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
|
|
;;
|
|
.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 determines the behavior when the output is empty.
|
|
If the output is empty and the exit status is zero,
|
|
the empty output is considered to be replacement text.
|
|
If the output is empty and the exit status is nonzero,
|
|
the original file is used.
|
|
For compatibility with previous versions of
|
|
.IR 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
|
|
.IR 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:
|
|
.
|
|
.RS 5m
|
|
.TS
|
|
l l.
|
|
ascii 8bcccbcc18b95.b
|
|
dos 8bcccbcc12bc5b95.b.
|
|
ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
|
|
9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
|
|
IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
|
|
191.b
|
|
iso8859 8bcccbcc18b95.33b.
|
|
koi8-r 8bcccbcc18b95.b128.
|
|
latin1 8bcccbcc18b95.33b.
|
|
next 8bcccbcc18b95.bb125.bb
|
|
.TE
|
|
.RE
|
|
.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, invalid 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 "%g"
|
|
Replaced by the shell-escaped name of the current input file.
|
|
This is useful when the expanded string will be used in a shell command,
|
|
such as in LESSEDIT.
|
|
.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 "%T"
|
|
Normally expands to the word "file".
|
|
However if viewing files via a tags list using the \-t option,
|
|
it expands to the word "tag".
|
|
.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(%T %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(%T\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x.:
|
|
?pB%pB\e%:byte\ %bB?s/%s...%t
|
|
.sp
|
|
?f%f\ .?n?m(%T\ %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(%T\ %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.\ %g
|
|
.sp
|
|
.fi
|
|
Note that this expands to the editor name, followed by a + and the
|
|
line number, followed by the shell-escaped 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)
|
|
.IP
|
|
history file
|
|
.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 option 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
|
|
.IR 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
|
|
.IR 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
|
|
.IR less .
|
|
If set to "\-" or "/dev/null", a history file is not used.
|
|
The default is "$XDG_STATE_HOME/lesshst" or "$HOME/.local/state/lesshst" or
|
|
"$XDG_DATA_HOME/lesshst" or "$HOME/.lesshst" on Unix systems,
|
|
"$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 LESSKEYIN
|
|
Name of the default
|
|
.I "lesskey source"
|
|
file.
|
|
.IP LESSKEY
|
|
Name of the default
|
|
.I "lesskey binary"
|
|
file. (Not used if "$LESSKEYIN" exists.)
|
|
.IP LESSKEYIN_SYSTEM
|
|
Name of the default system-wide
|
|
.I "lesskey source"
|
|
file.
|
|
.IP LESSKEY_SYSTEM
|
|
Name of the default system-wide
|
|
.I "lesskey binary"
|
|
file. (Not used if "$LESSKEYIN_SYSTEM" exists.)
|
|
.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
|
|
.IR 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"
|
|
.BR lesskey (1)
|
|
.
|
|
.SH COPYRIGHT
|
|
Copyright (C) 1984-2022 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
|
|
.
|
|
Mark Nudelman
|
|
.br
|
|
Report bugs at https://github.com/gwsw/less/issues.
|
|
.br
|
|
For more information, see the less homepage at
|
|
.br
|
|
https://greenwoodsoftware.com/less
|