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1578 lines
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1578 lines
58 KiB
Plaintext
.TH LESS 1 "Version 381: 17 Jan 2003"
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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 [-[+]aBcCdeEfFgGiIJLmMnNqQrRsSuUVwWX~]"
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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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.SH DESCRIPTION
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.I Less
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is a program similar to
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.I more
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(1), 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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.I vi
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(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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.I 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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.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 "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 "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 "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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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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.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 "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.
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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 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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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 letter,
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marks the current position with that letter.
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.IP "'"
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(Single quote.)
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Followed by any lowercase 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 /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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.I ed.
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The search starts at the second 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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.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 line immediately before the top line 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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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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.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 ":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 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 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
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.I less
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being run.
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.IP "q or Q or :q or :Q or ZZ"
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Exits
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.I 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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.PP
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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"
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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.
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A pound sign (#) is replaced by the name of the previously examined file.
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"!!" 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"
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<m> represents any mark letter.
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Pipes a section of the input file to the given shell command.
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The section of the file to be piped is between the first line on
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the current screen and the position marked by the letter.
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<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"
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Save the input to a file.
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This only works if the input is a pipe, not an ordinary file.
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.PP
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.SH OPTIONS
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Command line options are described below.
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Most options may be changed while
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.I less
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is running, via the "\-" command.
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.PP
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Most options may be given in one of two forms:
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either a dash followed by a single letter,
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or two dashes followed by a long option name.
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A long option name may be abbreviated as long as
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the abbreviation is unambiguous.
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|
For example, --quit-at-eof may be abbreviated --quit, but not
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--qui, since both --quit-at-eof and --quiet begin with --qui.
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Some long option names are in uppercase, such as --QUIT-AT-EOF, as
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distinct from --quit-at-eof.
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Such option names need only have their first letter capitalized;
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the remainder of the name may be in either case.
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For example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.
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.PP
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Options are also taken from the environment variable "LESS".
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|
For example,
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to avoid typing "less -options ..." each time
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.I less
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is invoked, you might tell
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.I csh:
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.sp
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setenv LESS "-options"
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.sp
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or if you use
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.I sh:
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.sp
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LESS="-options"; export LESS
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.sp
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|
On MS-DOS, you don't need the quotes, but you should replace any
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percent signs in the options string by double percent signs.
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|
.sp
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|
The environment variable is parsed before the command line,
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so command line options override the LESS environment variable.
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|
If an option appears in the LESS variable, it can be reset
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to its default value on the command line by beginning the command
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line option with "\-+".
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.sp
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|
For options like -P or -D which take a following string,
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a dollar sign ($) must be used to signal the end of the string.
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For example, to set two -D options on MS-DOS, you must have
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a dollar sign between them, like this:
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.sp
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LESS="-Dn9.1$-Ds4.1"
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.sp
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.IP "-? or --help"
|
|
This option displays a summary of the commands accepted by
|
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.I less
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|
(the same as the h command).
|
|
(Depending on how your shell interprets the question mark,
|
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it may be necessary to quote the question mark, thus: "-\e?".)
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|
.IP "-a or --search-skip-screen"
|
|
Causes searches to start after the last line
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displayed on the screen,
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thus skipping all lines displayed on the screen.
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|
By default, searches start at the second line on the screen
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(or after the last found line; see the -j option).
|
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.IP "-b\fIn\fP or --buffers=\fIn\fP"
|
|
Specifies the amount of buffer space
|
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.I less
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will use for each file, in units of kilobytes (1024 bytes).
|
|
By default 64K of buffer space is used for each file
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(unless the file is a pipe; see the -B option).
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The -b option specifies instead that \fIn\fP kilobytes of
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buffer space should be used for each file.
|
|
If \fIn\fP is -1, buffer space is unlimited; that is,
|
|
the entire file is read into memory.
|
|
.IP "-B or --auto-buffers"
|
|
By default, when data is read from a pipe,
|
|
buffers are allocated automatically as needed.
|
|
If a large amount of data is read from the pipe, this can cause
|
|
a large amount of memory to be allocated.
|
|
The -B option disables this automatic allocation of buffers for pipes,
|
|
so that only 64K
|
|
(or the amount of space specified by the -b option)
|
|
is used for the pipe.
|
|
Warning: use of -B can result in erroneous display, since only the
|
|
most recently viewed part of the file 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"
|
|
The -C option is like -c, but the screen is cleared before it is repainted.
|
|
.IP "-d or --dumb"
|
|
The -d option suppresses the error message
|
|
normally displayed if the terminal is dumb;
|
|
that is, lacks some important capability,
|
|
such as the ability to clear the screen or scroll backward.
|
|
The -d option does not otherwise change the behavior of
|
|
.I less
|
|
on a dumb terminal.
|
|
.IP "-D\fBx\fP\fIcolor\fP or --color=\fBx\fP\fIcolor\fP"
|
|
[MS-DOS only]
|
|
Sets the color of the text displayed.
|
|
\fBx\fP is a single character which selects the type of text whose color is
|
|
being set: n=normal, s=standout, d=bold, u=underlined, k=blink.
|
|
\fIcolor\fP is a pair of numbers separated by a period.
|
|
The first number selects the foreground color and the second selects
|
|
the background color of the text.
|
|
A single number \fIN\fP is the same as \fIN.0\fP.
|
|
.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.
|
|
.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.
|
|
A target line is the object of a text search,
|
|
tag search, jump to a line number,
|
|
jump to a file percentage, or jump to a marked position.
|
|
The screen line is 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.
|
|
If the -j option is used, searches begin at the line immediately
|
|
after the target line.
|
|
For example, if "-j4" is used, the target line is the
|
|
fourth line on the screen, so searches begin at the fifth line
|
|
on the screen.
|
|
.IP "-J or --status-column"
|
|
Displays a status column at the left edge of the screen.
|
|
The status column shows the lines that matched the current search.
|
|
The status column is also used if the -w or -W option is in effect.
|
|
.IP "-k\fIfilename\fP or --lesskey-file=\fIfilename\fP"
|
|
Causes
|
|
.I less
|
|
to open and interpret the named file as a
|
|
.I lesskey
|
|
(1) file.
|
|
Multiple -k options may be specified.
|
|
If the LESSKEY or LESSKEY_SYSTEM environment variable is set, or
|
|
if a lesskey file is found in a standard place (see KEY BINDINGS),
|
|
it is also used as a
|
|
.I lesskey
|
|
file.
|
|
.IP "-L or --no-lessopen"
|
|
Ignore the LESSOPEN environment variable
|
|
(see the INPUT PREPROCESSOR section below).
|
|
This option can be set from within \fIless\fP,
|
|
but it will apply only to files opened subsequently, not to the
|
|
file which is currently open.
|
|
.IP "-m or --long-prompt"
|
|
Causes
|
|
.I less
|
|
to prompt verbosely (like \fImore\fP),
|
|
with the percent into the file.
|
|
By default,
|
|
.I less
|
|
prompts with a colon.
|
|
.IP "-M or --LONG-PROMPT"
|
|
Causes
|
|
.I less
|
|
to prompt even more verbosely than
|
|
.I more.
|
|
.IP "-n or --line-numbers"
|
|
Suppresses line numbers.
|
|
The default (to use line numbers) may cause
|
|
.I less
|
|
to run more slowly in some cases, especially with a very large input file.
|
|
Suppressing line numbers with the -n option will avoid this problem.
|
|
Using line numbers means: the line number will be displayed in the verbose
|
|
prompt and in the = command,
|
|
and the v command will pass the current line number to the editor
|
|
(see also the discussion of LESSEDIT in PROMPTS below).
|
|
.IP "-N or --LINE-NUMBERS"
|
|
Causes a line number to be displayed at the beginning of
|
|
each line in the display.
|
|
.IP "-o\fIfilename\fP or --log-file=\fIfilename\fP"
|
|
Causes
|
|
.I less
|
|
to copy its input to the named file as it is being viewed.
|
|
This applies only when the input file is a pipe,
|
|
not an ordinary file.
|
|
If the file already exists,
|
|
.I less
|
|
will ask for confirmation before overwriting it.
|
|
.IP "-O\fIfilename\fP or --LOG-FILE=\fIfilename\fP"
|
|
The -O option is like -o, but it will overwrite an existing
|
|
file without asking for confirmation.
|
|
.sp
|
|
If no log file has been specified,
|
|
the -o and -O options can be used from within
|
|
.I less
|
|
to specify a log file.
|
|
Without a file name, they will simply report the name of the log file.
|
|
The "s" command is equivalent to specifying -o from within
|
|
.I less.
|
|
.IP "-p\fIpattern\fP or --pattern=\fIpattern\fP"
|
|
The -p option on the command line is equivalent to
|
|
specifying +/\fIpattern\fP;
|
|
that is, it tells
|
|
.I less
|
|
to start at the first occurrence of \fIpattern\fP in the file.
|
|
.IP "-P\fIprompt\fP or --prompt=\fIprompt\fP"
|
|
Provides a way to tailor the three prompt
|
|
styles to your own preference.
|
|
This option would normally be put in the LESS environment
|
|
variable, rather than being typed in with each
|
|
.I less
|
|
command.
|
|
Such an option must either be the last option in the LESS variable,
|
|
or be terminated by a dollar sign.
|
|
-Ps followed by a string changes the default (short) prompt
|
|
to that string.
|
|
-Pm changes the medium (-m) prompt.
|
|
-PM changes the long (-M) prompt.
|
|
-Ph changes the prompt for the help screen.
|
|
-P= changes the message printed by the = command.
|
|
-Pw changes the message printed while waiting for data (in the F command).
|
|
All prompt strings consist of a sequence of
|
|
letters and special escape sequences.
|
|
See the section on PROMPTS for more details.
|
|
.IP "-q or --quiet or --silent"
|
|
Causes moderately "quiet" operation:
|
|
the terminal bell is not rung
|
|
if an attempt is made to scroll past the end of the file
|
|
or before the beginning of the file.
|
|
If the terminal has a "visual bell", it is used instead.
|
|
The bell will be rung on certain other errors,
|
|
such as typing an invalid character.
|
|
The default is to ring the terminal bell in all such cases.
|
|
.IP "-Q or --QUIET or --SILENT"
|
|
Causes totally "quiet" operation:
|
|
the terminal bell is never rung.
|
|
.IP "-r or --raw-control-chars"
|
|
Causes "raw" control characters to be displayed.
|
|
The default is to display control characters using the caret notation;
|
|
for example, a control-A (octal 001) is displayed as "^A".
|
|
Warning: when the -r option is used,
|
|
.I less
|
|
cannot keep track of the actual appearance of the screen
|
|
(since this depends on how the screen responds to
|
|
each type of control character).
|
|
Thus, various display problems may result,
|
|
such as long lines being split in the wrong place.
|
|
.IP "-R or --RAW-CONTROL-CHARS"
|
|
Like -r, but tries to keep track of the screen appearance where possible.
|
|
This works only if the input consists of normal text and possibly some
|
|
ANSI "color" escape sequences, which are sequences of the form:
|
|
.sp
|
|
ESC [ ... m
|
|
.sp
|
|
where the "..." is zero or more characters other than "m".
|
|
For the purpose of keeping track of screen appearance,
|
|
all control characters and all ANSI color escape sequences are
|
|
assumed to not move the cursor.
|
|
You can make
|
|
.I less
|
|
think that characters other than "m" can end ANSI color escape sequences
|
|
by setting the environment variable LESSANSIENDCHARS to the list of
|
|
characters which can end a color escape sequence.
|
|
.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 rather than folded.
|
|
That is, the portion of a long line that does not fit in
|
|
the screen width is not shown.
|
|
The default is to fold long lines; that is, display the remainder
|
|
on the next line.
|
|
.IP "-t\fItag\fP or --tag=\fItag\fP"
|
|
The -t option, followed immediately by a TAG,
|
|
will edit the file containing that tag.
|
|
For this to work, tag information must be available;
|
|
for example, there may be a file in the current directory called "tags",
|
|
which was previously built by
|
|
.I ctags
|
|
(1) or an equivalent command.
|
|
If the environment variable LESSGLOBALTAGS is set, it is taken to be
|
|
the name of a command compatible with
|
|
.I global
|
|
(1), and that command is executed to find the tag.
|
|
(See http://www.gnu.org/software/global/global.html).
|
|
The -t option may also be specified from within
|
|
.I less
|
|
(using the \- command) as a way of examining a new file.
|
|
The command ":t" is equivalent to specifying -t from within
|
|
.I less.
|
|
.IP "-T\fItagsfile\fP or --tag-file=\fItagsfile\fP"
|
|
Specifies a tags file to be used instead of "tags".
|
|
.IP "-u or --underline-special"
|
|
Causes backspaces and carriage returns to be treated as printable characters;
|
|
that is, they are sent to the terminal when they appear in the input.
|
|
.IP "-U or --UNDERLINE-SPECIAL"
|
|
Causes backspaces, tabs and carriage returns to be
|
|
treated as control characters;
|
|
that is, they are handled as specified by the -r option.
|
|
.sp
|
|
By default, if neither -u nor -U is given,
|
|
backspaces which appear adjacent to an underscore character
|
|
are treated specially:
|
|
the underlined text is displayed
|
|
using the terminal's hardware underlining capability.
|
|
Also, backspaces which appear between two identical characters
|
|
are treated specially:
|
|
the overstruck text is printed
|
|
using the terminal's hardware boldface capability.
|
|
Other backspaces are deleted, along with the preceding character.
|
|
Carriage returns immediately followed by a newline are deleted.
|
|
other carriage returns are handled as specified by the -r option.
|
|
Text which is overstruck or underlined can be searched for
|
|
if neither -u nor -U is in effect.
|
|
.IP "-V or --version"
|
|
Displays the version number of
|
|
.I less.
|
|
.IP "-w or --hilite-unread"
|
|
Temporarily highlights the first "new" line after a forward movement
|
|
of a full page.
|
|
The first "new" line is the line immediately following the line previously
|
|
at the bottom of the screen.
|
|
Also highlights the target line after a g or p command.
|
|
The highlight is removed at the next command which causes movement.
|
|
The entire line is highlighted, unless the -J option is in effect,
|
|
in which case only the status column is highlighted.
|
|
.IP "-W or --HILITE-UNREAD"
|
|
Like -w, but temporarily highlights the first new line after any
|
|
forward movement command larger than one line.
|
|
.IP "-x\fIn\fP,... or --tabs=\fIn\fP,..."
|
|
Sets tab stops.
|
|
If only one \fIn\fP is specified, tab stops are set at multiples of \fIn\fP.
|
|
If multiple values separated by commas are specified, tab stops
|
|
are set at those positions, and then continue with the same spacing as the
|
|
last two.
|
|
For example, \fI-x9,17\fP will set tabs at positions 9, 17, 25, 33, etc.
|
|
The default for \fIn\fP is 8.
|
|
.IP "-X or --no-init"
|
|
Disables sending the termcap initialization and deinitialization strings
|
|
to the terminal.
|
|
This is sometimes desirable if the deinitialization string does
|
|
something unnecessary, like clearing the screen.
|
|
.IP "--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 "-y\fIn\fP or --max-forw-scroll=\fIn\fP"
|
|
Specifies a maximum number of lines to scroll forward.
|
|
If it is necessary to scroll forward more than \fIn\fP lines,
|
|
the screen is repainted instead.
|
|
The -c or -C option may be used to repaint from the top of
|
|
the screen if desired.
|
|
By default, any forward movement causes scrolling.
|
|
.IP "-[z]\fIn\fP or --window=\fIn\fP"
|
|
Changes the default scrolling window size to \fIn\fP lines.
|
|
The default is one screenful.
|
|
The z and w commands can also be used to change the window size.
|
|
The "z" may be omitted for compatibility with
|
|
.I more.
|
|
If the number
|
|
.I n
|
|
is negative, it indicates
|
|
.I n
|
|
lines less than the current screen size.
|
|
For example, if the screen is 24 lines, \fI-z-4\fP sets the
|
|
scrolling window to 20 lines. If the screen is resized to 40 lines,
|
|
the scrolling window automatically changes to 36 lines.
|
|
.IP "-\fI\(dqcc\fP\ or\ --quotes=\fIcc\fP"
|
|
Changes the filename quoting character.
|
|
This may be necessary if you are trying to name a file
|
|
which contains both spaces and quote characters.
|
|
Followed by a single character, this changes the quote character to that
|
|
character.
|
|
Filenames containing a space should then be surrounded by that character
|
|
rather than by double quotes.
|
|
Followed by two characters, changes the open quote to the first character,
|
|
and the close quote to the second character.
|
|
Filenames containing a space should then be preceded by the open quote
|
|
character and followed by the close quote character.
|
|
Note that even after the quote characters are changed, this option
|
|
remains -" (a dash followed by a double quote).
|
|
.IP "-~ or --tilde"
|
|
Normally lines after end of file are displayed as a single tilde (~).
|
|
This option causes lines after end of file to be displayed as blank lines.
|
|
.IP "-# or --shift"
|
|
Specifies the default number of positions to scroll horizontally
|
|
in the RIGHTARROW and LEFTARROW commands.
|
|
If the number specified is zero, it sets the default number of
|
|
positions to one half of the screen width.
|
|
.IP --
|
|
A command line argument of "--" marks the end of option arguments.
|
|
Any arguments following this are interpreted as filenames.
|
|
This can be useful when viewing a file whose name begins with a "-" or "+".
|
|
.IP +
|
|
If a command line option begins with \fB+\fP,
|
|
the remainder of that option is taken to be an initial command to
|
|
.I less.
|
|
For example, +G tells
|
|
.I less
|
|
to start at the end of the file rather than the beginning,
|
|
and +/xyz tells it to start at the first occurrence of "xyz" in the file.
|
|
As a special case, +<number> acts like +<number>g;
|
|
that is, it starts the display at the specified line number
|
|
(however, see the caveat under the "g" command above).
|
|
If the option starts with ++, the initial command applies to
|
|
every file being viewed, not just the first one.
|
|
The + command described previously
|
|
may also be used to set (or change) an initial command for every file.
|
|
|
|
.SH "LINE EDITING"
|
|
When entering command line at the bottom of the screen
|
|
(for example, a filename for the :e command,
|
|
or the pattern for a search command),
|
|
certain keys can be used to manipulate the command line.
|
|
Most commands have an alternate form in [ brackets ] which can be used if
|
|
a key does not exist on a particular keyboard.
|
|
(The bracketed forms do not work in the MS-DOS version.)
|
|
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.
|
|
.IP "DOWNARROW [ ESC-j ]"
|
|
Retrieve the next command line.
|
|
.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.
|
|
|
|
.SH "KEY BINDINGS"
|
|
You may define your own
|
|
.I less
|
|
commands by using the program
|
|
.I lesskey
|
|
(1)
|
|
to create a lesskey file.
|
|
This file specifies a set of command keys and an action
|
|
associated with each key.
|
|
You may also use
|
|
.I lesskey
|
|
to change the line-editing keys (see LINE EDITING),
|
|
and to set environment variables.
|
|
If the environment variable LESSKEY is set,
|
|
.I less
|
|
uses that as the name of the lesskey file.
|
|
Otherwise,
|
|
.I less
|
|
looks in a standard place for the lesskey file:
|
|
On Unix systems,
|
|
.I less
|
|
looks for a lesskey file called "$HOME/.less".
|
|
On MS-DOS and Windows systems,
|
|
.I less
|
|
looks for a lesskey file called "$HOME/_less", and if it is not found there,
|
|
then looks for a lesskey file called "_less" in any directory specified
|
|
in the PATH environment variable.
|
|
On OS/2 systems,
|
|
.I less
|
|
looks for a lesskey file called "$HOME/less.ini", and if it is not found,
|
|
then looks for a lesskey file called "less.ini" in any directory specified
|
|
in the INIT environment variable, and if it not found there,
|
|
then looks for a lesskey file called "less.ini" in any directory specified
|
|
in the PATH environment variable.
|
|
See the
|
|
.I lesskey
|
|
manual page for more details.
|
|
.P
|
|
A system-wide lesskey file may also be set up to provide key bindings.
|
|
If a key is defined in both a local lesskey file and in the
|
|
system-wide file, key bindings in the local file take precedence over
|
|
those in the system-wide file.
|
|
If the environment variable LESSKEY_SYSTEM is set,
|
|
.I less
|
|
uses that as the name of the system-wide lesskey file.
|
|
Otherwise,
|
|
.I less
|
|
looks in a standard place for the system-wide lesskey file:
|
|
On Unix systems, the system-wide lesskey file is /usr/local/etc/sysless.
|
|
(However, if
|
|
.I less
|
|
was built with a different sysconf directory than /usr/local/etc,
|
|
that directory is where the sysless file is found.)
|
|
On MS-DOS and Windows systems, the system-wide lesskey file is c:\e_sysless.
|
|
On OS/2 systems, the system-wide lesskey file is c:\esysless.ini.
|
|
|
|
.SH "INPUT PREPROCESSOR"
|
|
You may define an "input preprocessor" for
|
|
.I less.
|
|
Before
|
|
.I less
|
|
opens a file, it first gives your input preprocessor a chance to modify the
|
|
way the contents of the file are displayed.
|
|
An input preprocessor is simply an executable program (or shell script),
|
|
which writes the contents of the file to a different file,
|
|
called the replacement file.
|
|
The contents of the replacement file are then displayed
|
|
in place of the contents of the original file.
|
|
However, it will appear to the user as if the original file is opened;
|
|
that is,
|
|
.I less
|
|
will display the original filename as the name of the current file.
|
|
.PP
|
|
An input preprocessor receives one command line argument, the original filename,
|
|
as entered by the user.
|
|
It should create the replacement file, and when finished,
|
|
print the name of the replacement file to its standard output.
|
|
If the input preprocessor does not output a replacement filename,
|
|
.I less
|
|
uses the original file, as normal.
|
|
The input preprocessor is not called when viewing standard input.
|
|
To set up an input preprocessor, set the LESSOPEN environment variable
|
|
to a command line which will invoke your input preprocessor.
|
|
This command line should include one occurrence of the string "%s",
|
|
which will be replaced by the filename
|
|
when the input preprocessor command is invoked.
|
|
.PP
|
|
When
|
|
.I less
|
|
closes a file opened in such a way, it will call another program,
|
|
called the input postprocessor,
|
|
which may perform any desired clean-up action (such as deleting the
|
|
replacement file created by LESSOPEN).
|
|
This program receives two command line arguments, the original filename
|
|
as entered by the user, and the name of the replacement file.
|
|
To set up an input postprocessor, set the LESSCLOSE environment variable
|
|
to a command line which will invoke your input postprocessor.
|
|
It may include two occurrences of the string "%s";
|
|
the first is replaced with the original name of the file and
|
|
the second with the name of the replacement file,
|
|
which was output by LESSOPEN.
|
|
.PP
|
|
For example, on many Unix systems, these two scripts will allow you
|
|
to keep files in compressed format, but still let
|
|
.I less
|
|
view them directly:
|
|
.PP
|
|
lessopen.sh:
|
|
.br
|
|
#! /bin/sh
|
|
.br
|
|
case "$1" in
|
|
.br
|
|
*.Z) uncompress -c $1 >/tmp/less.$$ 2>/dev/null
|
|
.br
|
|
if [ -s /tmp/less.$$ ]; then
|
|
.br
|
|
echo /tmp/less.$$
|
|
.br
|
|
else
|
|
.br
|
|
rm -f /tmp/less.$$
|
|
.br
|
|
fi
|
|
.br
|
|
;;
|
|
.br
|
|
esac
|
|
.PP
|
|
lessclose.sh:
|
|
.br
|
|
#! /bin/sh
|
|
.br
|
|
rm $2
|
|
.PP
|
|
To use these scripts, put them both where they can be executed and
|
|
set LESSOPEN="lessopen.sh\ %s", and
|
|
LESSCLOSE="lessclose.sh\ %s\ %s".
|
|
More complex LESSOPEN and LESSCLOSE scripts may be written
|
|
to accept other types of compressed files, and so on.
|
|
.PP
|
|
It is also possible to set up an input preprocessor to
|
|
pipe the file data directly to
|
|
.I less,
|
|
rather than putting the data into a replacement file.
|
|
This avoids the need to decompress the entire file before
|
|
starting to view it.
|
|
An input preprocessor that works this way is called an input pipe.
|
|
An input pipe, instead of writing the name of a replacement file on
|
|
its standard output,
|
|
writes the entire contents of the replacement file on its standard output.
|
|
If the input pipe does not write any characters on its standard output,
|
|
then there is no replacement file and
|
|
.I less
|
|
uses the original file, as normal.
|
|
To use an input pipe,
|
|
make the first character in the LESSOPEN environment variable a
|
|
vertical bar (|) to signify that the input preprocessor is an input pipe.
|
|
.PP
|
|
For example, on many Unix systems, this script will work like the
|
|
previous example scripts:
|
|
.PP
|
|
lesspipe.sh:
|
|
.br
|
|
#! /bin/sh
|
|
.br
|
|
case "$1" in
|
|
.br
|
|
*.Z) uncompress -c $1 2>/dev/null
|
|
.br
|
|
;;
|
|
.br
|
|
esac
|
|
.br
|
|
.PP
|
|
To use this script, put it where it can be executed and set
|
|
LESSOPEN="|lesspipe.sh %s".
|
|
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 "-".
|
|
|
|
.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.
|
|
.PP
|
|
In special cases, it may be desired to tailor
|
|
.I less
|
|
to use a character set other than the ones definable by LESSCHARSET.
|
|
In this case, the environment variable LESSCHARDEF can be used
|
|
to define a character set.
|
|
It should be set to a string where each character in the string represents
|
|
one character in the character set.
|
|
The character "." is used for a normal character, "c" for control,
|
|
and "b" for binary.
|
|
A decimal number may be used for repetition.
|
|
For example, "bccc4b." would mean character 0 is binary,
|
|
1, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8 is normal.
|
|
All characters after the last are taken to be the same as the last,
|
|
so characters 9 through 255 would be normal.
|
|
(This is an example, and does not necessarily
|
|
represent any real character set.)
|
|
.PP
|
|
This table shows the value of LESSCHARDEF which is equivalent
|
|
to each of the possible values for LESSCHARSET:
|
|
.sp
|
|
ascii\ 8bcccbcc18b95.b
|
|
.br
|
|
dos\ \ \ 8bcccbcc12bc5b95.b.
|
|
.br
|
|
ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
|
|
.br
|
|
\ \ \ \ \ \ 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
|
|
.br
|
|
IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
|
|
.br
|
|
\ \ \ \ \ \ 191.b
|
|
.br
|
|
iso8859 8bcccbcc18b95.33b.
|
|
.br
|
|
koi8-r 8bcccbcc18b95.b128.
|
|
.br
|
|
latin1 8bcccbcc18b95.33b.
|
|
.br
|
|
next\ \ 8bcccbcc18b95.bb125.bb
|
|
.PP
|
|
If neither LESSCHARSET nor LESSCHARDEF is set,
|
|
but the string "UTF-8" is found in the LC_ALL, LC_TYPE 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<%X>".
|
|
|
|
.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 "%i"
|
|
Replaced by the index of the current file in the list of
|
|
input files.
|
|
.IP "%l\fIX\fP"
|
|
Replaced by the line number of a line in the input file.
|
|
The line to be used is determined by the \fIX\fP, as with the %b option.
|
|
.IP "%L"
|
|
Replaced by the line number of the last line in the input file.
|
|
.IP "%m"
|
|
Replaced by the total number of input files.
|
|
.IP "%p\fIX\fP"
|
|
Replaced by the percent into the current input file, based on byte offsets.
|
|
The line used is determined by the \fIX\fP as with the %b option.
|
|
.IP "%P\fIX\fP"
|
|
Replaced by the percent into the current input file, based on line numbers.
|
|
The line used is determined by the \fIX\fP as with the %b option.
|
|
.IP "%s"
|
|
Same as %B.
|
|
.IP "%t"
|
|
Causes any trailing spaces to be removed.
|
|
Usually used at the end of the string, but may appear anywhere.
|
|
.IP "%x"
|
|
Replaced by the name of the next input file in the list.
|
|
.PP
|
|
If any item is unknown (for example, the file size if input
|
|
is a pipe), a question mark is printed instead.
|
|
.PP
|
|
The format of the prompt string can be changed
|
|
depending on certain conditions.
|
|
A question mark followed by a single character acts like an "IF":
|
|
depending on the following character, a condition is evaluated.
|
|
If the condition is true, any characters following the question mark
|
|
and condition character, up to a period, are included in the prompt.
|
|
If the condition is false, such characters are not included.
|
|
A colon appearing between the question mark and the
|
|
period can be used to establish an "ELSE": any characters between
|
|
the colon and the period are included in the string if and only if
|
|
the IF condition is false.
|
|
Condition characters (which follow a question mark) may be:
|
|
.IP "?a"
|
|
True if any characters have been included in the prompt so far.
|
|
.IP "?b\fIX\fP"
|
|
True if the byte offset of the specified line is known.
|
|
.IP "?B"
|
|
True if the size of current input file is known.
|
|
.IP "?c"
|
|
True if the text is horizontally shifted (%c is not zero).
|
|
.IP "?d\fIX\fP"
|
|
True if the page number of the specified line is known.
|
|
.IP "?e"
|
|
True if at end-of-file.
|
|
.IP "?f"
|
|
True if there is an input filename
|
|
(that is, if input is not a pipe).
|
|
.IP "?l\fIX\fP"
|
|
True if the line number of the specified line is known.
|
|
.IP "?L"
|
|
True if the line number of the last line in the file is known.
|
|
.IP "?m"
|
|
True if there is more than one input file.
|
|
.IP "?n"
|
|
True if this is the first prompt in a new input file.
|
|
.IP "?p\fIX\fP"
|
|
True if the percent into the current input file, based on byte offsets,
|
|
of the specified line is known.
|
|
.IP "?P\fIX\fP"
|
|
True if the percent into the current input file, based on line numbers,
|
|
of the specified line is known.
|
|
.IP "?s"
|
|
Same as "?B".
|
|
.IP "?x"
|
|
True if there is a next input file
|
|
(that is, if the current input file is not the last one).
|
|
.PP
|
|
Any characters other than the special ones
|
|
(question mark, colon, period, percent, and backslash)
|
|
become literally part of the prompt.
|
|
Any of the special characters may be included in the prompt literally
|
|
by preceding it with a backslash.
|
|
.PP
|
|
Some examples:
|
|
.sp
|
|
?f%f:Standard input.
|
|
.sp
|
|
This prompt prints the filename, if known;
|
|
otherwise the string "Standard input".
|
|
.sp
|
|
?f%f .?ltLine %lt:?pt%pt\e%:?btByte %bt:-...
|
|
.sp
|
|
This prompt would print the filename, if known.
|
|
The filename is followed by the line number, if known,
|
|
otherwise the percent if known, otherwise the byte offset if known.
|
|
Otherwise, a dash is printed.
|
|
Notice how each question mark has a matching period,
|
|
and how the % after the %pt
|
|
is included literally by escaping it with a backslash.
|
|
.sp
|
|
?n?f%f\ .?m(file\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x..%t
|
|
.sp
|
|
This prints the filename if this is the first prompt in a file,
|
|
followed by the "file N of N" message if there is more
|
|
than one input file.
|
|
Then, if we are at end-of-file, the string "(END)" is printed
|
|
followed by the name of the next file, if there is one.
|
|
Finally, any trailing spaces are truncated.
|
|
This is the default prompt.
|
|
For reference, here are the defaults for
|
|
the other two prompts (-m and -M respectively).
|
|
Each is broken into two lines here for readability only.
|
|
.nf
|
|
.sp
|
|
?n?f%f\ .?m(file\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x.:
|
|
?pB%pB\e%:byte\ %bB?s/%s...%t
|
|
.sp
|
|
?f%f\ .?n?m(file\ %i\ of\ %m)\ ..?ltlines\ %lt-%lb?L/%L.\ :
|
|
byte\ %bB?s/%s.\ .?e(END)\ ?x-\ Next\e:\ %x.:?pB%pB\e%..%t
|
|
.sp
|
|
.fi
|
|
And here is the default message produced by the = command:
|
|
.nf
|
|
.sp
|
|
?f%f\ .?m(file\ %i\ of\ %m)\ .?ltlines\ %lt-%lb?L/%L.\ .
|
|
byte\ %bB?s/%s.\ ?e(END)\ :?pB%pB\e%..%t
|
|
.fi
|
|
.PP
|
|
The prompt expansion features are also used for another purpose:
|
|
if an environment variable LESSEDIT is defined, it is used
|
|
as the command to be executed when the v command is invoked.
|
|
The LESSEDIT string is expanded in the same way as the prompt strings.
|
|
The default value for LESSEDIT is:
|
|
.nf
|
|
.sp
|
|
%E\ ?lm+%lm.\ %f
|
|
.sp
|
|
.fi
|
|
Note that this expands to the editor name, followed by a + and the
|
|
line number, followed by the file name.
|
|
If your editor does not accept the "+linenumber" syntax, or has other
|
|
differences in invocation syntax, the LESSEDIT variable can be
|
|
changed to modify this default.
|
|
|
|
.SH SECURITY
|
|
When the environment variable LESSSECURE is set to 1,
|
|
.I less
|
|
runs in a "secure" mode.
|
|
This means these features are disabled:
|
|
.RS
|
|
.IP "!"
|
|
the shell command
|
|
.IP "|"
|
|
the pipe command
|
|
.IP ":e"
|
|
the examine command.
|
|
.IP "v"
|
|
the editing command
|
|
.IP "s -o"
|
|
log files
|
|
.IP "-k"
|
|
use of lesskey files
|
|
.IP "-t"
|
|
use of tags files
|
|
.IP " "
|
|
metacharacters in filenames, such as *
|
|
.IP " "
|
|
filename completion (TAB, ^L)
|
|
.RE
|
|
.PP
|
|
Less can also be compiled to be permanently in "secure" mode.
|
|
|
|
.SH "ENVIRONMENT VARIABLES"
|
|
Environment variables may be specified either in the system environment
|
|
as usual, or in a
|
|
.I lesskey
|
|
(1) file.
|
|
If environment variables are defined in more than one place,
|
|
variables defined in a local lesskey file take precedence over
|
|
variables defined in the system environment, which take precedence
|
|
over variables defined in the system-wide lesskey file.
|
|
.IP COLUMNS
|
|
Sets the number of columns on the screen.
|
|
Takes precedence over the number of columns specified by the TERM variable.
|
|
(But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD,
|
|
the window system's idea of the screen size takes precedence over the
|
|
LINES and COLUMNS environment variables.)
|
|
.IP EDITOR
|
|
The name of the editor (used for the v command).
|
|
.IP HOME
|
|
Name of the user's home directory
|
|
(used to find a lesskey file on Unix and OS/2 systems).
|
|
.IP "HOMEDRIVE, HOMEPATH"
|
|
Concatenation of the HOMEDRIVE and HOMEPATH environment variables is
|
|
the name of the user's home directory if the HOME variable is not set
|
|
(only in the Windows version).
|
|
.IP INIT
|
|
Name of the user's init directory (used to find a lesskey file on OS/2 systems).
|
|
.IP LANG
|
|
Language for determining the character set.
|
|
.IP LC_CTYPE
|
|
Language for determining the character set.
|
|
.IP LESS
|
|
Options which are passed to
|
|
.I less
|
|
automatically.
|
|
.IP LESSANSIENDCHARS
|
|
Characters which are assumed to end an ANSI color escape sequence
|
|
(default "m").
|
|
.IP LESSBINFMT
|
|
Format for displaying non-printable, non-control characters.
|
|
.IP LESSCHARDEF
|
|
Defines a character set.
|
|
.IP LESSCHARSET
|
|
Selects a predefined character set.
|
|
.IP LESSCLOSE
|
|
Command line to invoke the (optional) input-postprocessor.
|
|
.IP LESSECHO
|
|
Name of the lessecho program (default "lessecho").
|
|
The lessecho program is needed to expand metacharacters, such as * and ?,
|
|
in filenames on Unix systems.
|
|
.IP LESSEDIT
|
|
Editor prototype string (used for the v command).
|
|
See discussion under PROMPTS.
|
|
.IP LESSGLOBALTAGS
|
|
Name of the command used by the -t option to find global tags.
|
|
Normally should be set to "global" if your system has the
|
|
.I global
|
|
(1) command. If not set, global tags are not used.
|
|
.IP LESSKEY
|
|
Name of the default lesskey(1) file.
|
|
.IP LESSKEY_SYSTEM
|
|
Name of the default system-wide lesskey(1) file.
|
|
.IP LESSMETACHARS
|
|
List of characters which are considered "metacharacters" by the shell.
|
|
.IP LESSMETAESCAPE
|
|
Prefix which less will add before each metacharacter in a
|
|
command sent to the shell.
|
|
If LESSMETAESCAPE is an empty string, commands containing
|
|
metacharacters will not be passed to the shell.
|
|
.IP LESSOPEN
|
|
Command line to invoke the (optional) input-preprocessor.
|
|
.IP LESSSECURE
|
|
Runs less in "secure" mode.
|
|
See discussion under SECURITY.
|
|
.IP LESSSEPARATOR
|
|
String to be appended to a directory name in filename completion.
|
|
.IP 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 PATH
|
|
User's search path (used to find a lesskey file
|
|
on MS-DOS and OS/2 systems).
|
|
.IP SHELL
|
|
The shell used to execute the ! command, as well as to expand filenames.
|
|
.IP TERM
|
|
The type of terminal on which
|
|
.I less
|
|
is being run.
|
|
.IP VISUAL
|
|
The name of the editor (used for the v command).
|
|
|
|
.SH "SEE ALSO"
|
|
lesskey(1)
|
|
|
|
.SH WARNINGS
|
|
The = command and prompts (unless changed by -P)
|
|
report the line numbers of the lines at the top and bottom of the screen,
|
|
but the byte and percent of the line after the one at the bottom of the screen.
|
|
.PP
|
|
If the :e command is used to name more than one file,
|
|
and one of the named files has been viewed previously,
|
|
the new files may be entered into the list in an unexpected order.
|
|
.PP
|
|
On certain older terminals (the so-called "magic cookie" terminals),
|
|
search highlighting will cause an erroneous display.
|
|
On such terminals, search highlighting is disabled by default
|
|
to avoid possible problems.
|
|
.PP
|
|
In certain cases, when search highlighting is enabled and
|
|
a search pattern begins with a ^,
|
|
more text than the matching string may be highlighted.
|
|
(This problem does not occur when less is compiled to use the POSIX
|
|
regular expression package.)
|
|
.PP
|
|
When viewing text containing ANSI color escape sequences using the -R option,
|
|
searching will not find text containing an embedded escape sequence.
|
|
Also, search highlighting may change the color of some of the text
|
|
which follows the highlighted text.
|
|
.PP
|
|
On some systems,
|
|
.I setlocale
|
|
claims that ASCII characters 0 thru 31 are control characters
|
|
rather than binary characters.
|
|
This causes
|
|
.I less
|
|
to treat some binary files as ordinary, non-binary files.
|
|
To workaround this problem, set the environment variable
|
|
LESSCHARSET to "ascii" (or whatever character set is appropriate).
|
|
.PP
|
|
See http://www.greenwoodsoftware.com/less for the latest list of known bugs in this
|
|
version of less.
|
|
|
|
.SH COPYRIGHT
|
|
Copyright (C) 2002 Mark Nudelman
|
|
.PP
|
|
less is part of the GNU project and is free software.
|
|
You can redistribute it and/or modify it
|
|
under the terms of either
|
|
(1) the GNU General Public License as published by
|
|
the Free Software Foundation; or (2) the Less License.
|
|
See the file README in the less distribution for more details
|
|
regarding redistribution.
|
|
You should have received a copy of the GNU General Public License
|
|
along with the source for less; see the file COPYING.
|
|
If not, write to the Free Software Foundation, 59 Temple Place,
|
|
Suite 330, Boston, MA 02111-1307, USA.
|
|
You should also have received a copy of the Less License;
|
|
see the file LICENSE.
|
|
.PP
|
|
less is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
or FITNESS FOR A PARTICULAR PURPOSE.
|
|
See the GNU General Public License for more details.
|
|
|
|
.SH AUTHOR
|
|
.PP
|
|
Mark Nudelman <markn@greenwoodsoftware.com>
|
|
.br
|
|
Send bug reports or comments to the above address or to bug-less@gnu.org.
|
|
.br
|
|
For more information, see the less homepage at http://www.greenwoodsoftware.com/less.
|