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MFC after: 2 weeks
1584 lines
79 KiB
Groff
1584 lines
79 KiB
Groff
LESS(1) LESS(1)
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[1mNAME[0m
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less - opposite of more
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[1mSYNOPSIS[0m
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[1mless -?[0m
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[1mless --help[0m
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[1mless -V[0m
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[1mless --version[0m
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[1mless [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~][0m
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[1m[-b [4m[22mspace[24m[1m] [-h [4m[22mlines[24m[1m] [-j [4m[22mline[24m[1m] [-k [4m[22mkeyfile[24m[1m][0m
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[1m[-{oO} [4m[22mlogfile[24m[1m] [-p [4m[22mpattern[24m[1m] [-P [4m[22mprompt[24m[1m] [-t [4m[22mtag[24m[1m][0m
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[1m[-T [4m[22mtagsfile[24m[1m] [-x [4m[22mtab[24m[1m,...] [-y [4m[22mlines[24m[1m] [-[z] [4m[22mlines[24m[1m][0m
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[1m[-# [4m[22mshift[24m[1m] [+[+][4m[22mcmd[24m[1m] [--] [[4m[22mfilename[24m[1m]...[0m
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(See the OPTIONS section for alternate option syntax with long option
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names.)
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[1mDESCRIPTION[0m
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[4mLess[24m is a program similar to [4mmore[24m (1), but which allows backward move-
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ment in the file as well as forward movement. Also, [4mless[24m does not have
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to read the entire input file before starting, so with large input
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files it starts up faster than text editors like [4mvi[24m (1). [4mLess[24m uses
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termcap (or terminfo on some systems), so it can run on a variety of
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terminals. There is even limited support for hardcopy terminals. (On
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a hardcopy terminal, lines which should be printed at the top of the
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screen are prefixed with a caret.)
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Commands are based on both [4mmore[24m and [4mvi.[24m Commands may be preceded by a
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decimal number, called N in the descriptions below. The number is used
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by some commands, as indicated.
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[1mCOMMANDS[0m
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In the following descriptions, ^X means control-X. ESC stands for the
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ESCAPE key; for example ESC-v means the two character sequence
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"ESCAPE", then "v".
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h or H Help: display a summary of these commands. If you forget all
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the other commands, remember this one.
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SPACE or ^V or f or ^F
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Scroll forward N lines, default one window (see option -z
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below). If N is more than the screen size, only the final
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screenful is displayed. Warning: some systems use ^V as a spe-
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cial literalization character.
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z Like SPACE, but if N is specified, it becomes the new window
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size.
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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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ENTER or RETURN or ^N or e or ^E or j or ^J
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Scroll forward N lines, default 1. The entire N lines are dis-
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played, even if N is more than the screen size.
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d or ^D
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Scroll forward N lines, default one half of the screen size. If
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N is specified, it becomes the new default for subsequent d and
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u commands.
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b or ^B or ESC-v
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Scroll backward N lines, default one window (see option -z
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below). If N is more than the screen size, only the final
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screenful is displayed.
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w Like ESC-v, but if N is specified, it becomes the new window
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size.
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y or ^Y or ^P or k or ^K
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Scroll backward N lines, default 1. The entire N lines are dis-
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played, even if N is more than the screen size. Warning: some
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systems use ^Y as a special job control character.
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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 subsequent d
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and u commands.
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ESC-) or RIGHTARROW
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Scroll horizontally right N characters, default half the screen
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width (see the -# option). If a number N is specified, it
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becomes the default for future RIGHTARROW and LEFTARROW com-
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mands. While the text is scrolled, it acts as though the -S
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option (chop lines) were in effect.
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ESC-( or LEFTARROW
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Scroll horizontally left N characters, default half the screen
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width (see the -# option). If a number N is specified, it
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becomes the default for future RIGHTARROW and LEFTARROW com-
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mands.
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r or ^R or ^L
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Repaint the screen.
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R Repaint the screen, discarding any buffered input. Useful if
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the file is changing while it is being viewed.
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F Scroll forward, and keep trying to read when the end of file is
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reached. Normally this command would be used when already at
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the end of the file. It is a way to monitor the tail of a file
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which is growing while it is being viewed. (The behavior is
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similar to the "tail -f" command.)
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g or < or ESC-<
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Go to line N in the file, default 1 (beginning of file). (Warn-
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ing: this may be slow if N is large.)
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G or > or ESC->
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Go to line N in the file, default the end of the file. (Warn-
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ing: this may be slow if N is large, or if N is not specified
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and standard input, rather than a file, is being read.)
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p or % Go to a position N percent into the file. N should be between 0
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and 100, and may contain a decimal point.
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P Go to the line containing byte offset N in the file.
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{ If a left curly bracket appears in the top line displayed on the
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screen, the { command will go to the matching right curly
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bracket. The matching right curly bracket is positioned on the
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bottom line of the screen. If there is more than one left curly
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bracket on the top line, a number N may be used to specify the
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N-th bracket on the line.
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} If a right curly bracket appears in the bottom line displayed on
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the screen, the } command will go to the matching left curly
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bracket. The matching left curly bracket is positioned on the
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top line of the screen. If there is more than one right curly
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bracket on the top line, a number N may be used to specify the
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N-th bracket on the line.
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( Like {, but applies to parentheses rather than curly brackets.
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) Like }, but applies to parentheses rather than curly brackets.
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[ Like {, but applies to square brackets rather than curly brack-
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ets.
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] Like }, but applies to square brackets rather than curly brack-
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ets.
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ESC-^F Followed by two characters, acts like {, but uses the two char-
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acters as open and close brackets, respectively. For example,
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"ESC ^F < >" could be used to go forward to the > which matches
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the < in the top displayed line.
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ESC-^B Followed by two characters, acts like }, but uses the two char-
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acters as open and close brackets, respectively. For example,
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"ESC ^B < >" could be used to go backward to the < which matches
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the > in the bottom displayed line.
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m Followed by any lowercase letter, marks the current position
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with that letter.
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' (Single quote.) Followed by any lowercase letter, returns to
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the position which was previously marked with that letter. Fol-
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lowed by another single quote, returns to the position at which
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the last "large" movement command was executed. Followed by a ^
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or $, jumps to the beginning or end of the file respectively.
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Marks are preserved when a new file is examined, so the ' com-
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mand can be used to switch between input files.
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^X^X Same as single quote.
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/pattern
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Search forward in the file for the N-th line containing the pat-
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tern. N defaults to 1. The pattern is a regular expression, as
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recognized by the regular expression library supplied by your
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system. The search starts at the first line displayed (but see
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the -a and -j options, which change this).
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Certain characters are special if entered at the beginning of
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the pattern; they modify the type of search rather than become
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part of the pattern:
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^N or !
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Search for lines which do NOT match the pattern.
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^E or *
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Search multiple files. That is, if the search reaches
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the END of the current file without finding a match, the
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search continues in the next file in the command line
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list.
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^F or @
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Begin the search at the first line of the FIRST file in
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the command line list, regardless of what is currently
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displayed on the screen or the settings of the -a or -j
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options.
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^K Highlight any text which matches the pattern on the cur-
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rent screen, but don't move to the first match (KEEP cur-
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rent position).
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^R Don't interpret regular expression metacharacters; that
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is, do a simple textual comparison.
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?pattern
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Search backward in the file for the N-th line containing the
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pattern. The search starts at the line immediately before the
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top line displayed.
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Certain characters are special as in the / command:
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^N or !
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Search for lines which do NOT match the pattern.
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^E or *
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Search multiple files. That is, if the search reaches
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the beginning of the current file without finding a
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match, the search continues in the previous file in the
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command line list.
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^F or @
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Begin the search at the last line of the last file in the
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command line list, regardless of what is currently dis-
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played on the screen or the settings of the -a or -j
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options.
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^K As in forward searches.
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^R As in forward searches.
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ESC-/pattern
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Same as "/*".
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ESC-?pattern
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Same as "?*".
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n Repeat previous search, for N-th line containing the last pat-
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tern. If the previous search was modified by ^N, the search is
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made for the N-th line NOT containing the pattern. If the pre-
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vious search was modified by ^E, the search continues in the
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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. There is no effect if the
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previous search was modified by ^F or ^K.
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N Repeat previous search, but in the reverse direction.
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ESC-n Repeat previous search, but crossing file boundaries. The
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effect is as if the previous search were modified by *.
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ESC-N Repeat previous search, but in the reverse direction and cross-
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ing file boundaries.
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ESC-u Undo search highlighting. Turn off highlighting of strings
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matching the current search pattern. If highlighting is already
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off because of a previous ESC-u command, turn highlighting back
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on. Any search command will also turn highlighting back on.
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(Highlighting can also be disabled by toggling the -G option; in
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that case search commands do not turn highlighting back on.)
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&pattern
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Display only lines which match the pattern; lines which do not
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match the pattern are not displayed. If pattern is empty (if
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you type & immediately followed by ENTER), any filtering is
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turned off, and all lines are displayed. While filtering is in
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effect, an ampersand is displayed at the beginning of the
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prompt, as a reminder that some lines in the file may be hidden.
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Certain characters are special as in the / command:
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^N or !
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Display only lines which do NOT match the pattern.
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^R Don't interpret regular expression metacharacters; that
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is, do a simple textual comparison.
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:e [filename]
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Examine a new file. If the filename is missing, the "current"
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file (see the :n and :p commands below) from the list of files
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in the command line is re-examined. A percent sign (%) in the
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filename is replaced by the name of the current file. A pound
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sign (#) is replaced by the name of the previously examined
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file. However, two consecutive percent signs are simply
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replaced with a single percent sign. This allows you to enter a
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filename that contains a percent sign in the name. Similarly,
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two consecutive pound signs are replaced with a single pound
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sign. The filename is inserted into the command line list of
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files 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
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into the list of files and the first one is examined. If the
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filename contains one or more spaces, the entire filename should
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be enclosed in double quotes (also see the -" option).
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^X^V or E
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Same as :e. Warning: some systems use ^V as a special literal-
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ization character. On such systems, you may not be able to use
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^V.
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:n Examine the next file (from the list of files given in the com-
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mand line). If a number N is specified, the N-th next file is
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examined.
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:p Examine the previous file in the command line list. If a number
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N is specified, the N-th previous file is examined.
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:x Examine the first file in the command line list. If a number N
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is specified, the N-th file in the list is examined.
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:d Remove the current file from the list of files.
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t Go to the next tag, if there were more than one matches for the
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current tag. See the -t option for more details about tags.
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T Go to the previous tag, if there were more than one matches for
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the current tag.
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= or ^G or :f
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Prints some information about the file being viewed, including
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its name and the line number and byte offset of the bottom line
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being displayed. If possible, it also prints the length of the
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file, the number of lines in the file and the percent of the
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file above the last displayed line.
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- Followed by one of the command line option letters (see OPTIONS
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below), this will change the setting of that option and print a
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message describing the new setting. If a ^P (CONTROL-P) is
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entered immediately after the dash, the setting of the option is
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changed but no message is printed. If the option letter has a
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numeric value (such as -b or -h), or a string value (such as -P
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or -t), a new value may be entered after the option letter. If
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no new value is entered, a message describing the current set-
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ting is printed and nothing is changed.
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-- Like the - command, but takes a long option name (see OPTIONS
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below) rather than a single option letter. You must press ENTER
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or RETURN after typing the option name. A ^P immediately after
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the second dash suppresses printing of a message describing the
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new setting, as in the - command.
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-+ Followed by one of the command line option letters this will
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reset the option to its default setting and print a message
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describing the new setting. (The "-+[4mX[24m" command does the same
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thing as "-+[4mX[24m" on the command line.) This does not work for
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string-valued options.
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--+ Like the -+ command, but takes a long option name rather than a
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single option letter.
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-! Followed by one of the command line option letters, this will
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reset the option to the "opposite" of its default setting and
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print a message describing the new setting. This does not work
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for numeric or string-valued options.
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--! Like the -! command, but takes a long option name rather than a
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single option letter.
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_ (Underscore.) Followed by one of the command line option let-
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ters, this will print a message describing the current setting
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of that option. The setting of the option is not changed.
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__ (Double underscore.) Like the _ (underscore) command, but takes
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a long option name rather than a single option letter. You must
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press ENTER or RETURN after typing the option name.
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+cmd Causes the specified cmd to be executed each time a new file is
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examined. For example, +G causes [4mless[24m to initially display each
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file starting at the end rather than the beginning.
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V Prints the version number of [4mless[24m being run.
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q or Q or :q or :Q or ZZ
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Exits [4mless.[0m
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The following four commands may or may not be valid, depending on your
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particular installation.
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v Invokes an editor to edit the current file being viewed. The
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editor is taken from the environment variable VISUAL if defined,
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or EDITOR if VISUAL is not defined, or defaults to "vi" if nei-
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ther VISUAL nor EDITOR is defined. See also the discussion of
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LESSEDIT under the section on PROMPTS below.
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! shell-command
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Invokes a shell to run the shell-command given. A percent sign
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(%) in the command is replaced by the name of the current file.
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A pound sign (#) is replaced by the name of the previously exam-
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ined file. "!!" repeats the last shell command. "!" with no
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shell command simply invokes a shell. On Unix systems, the
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shell is taken from the environment variable SHELL, or defaults
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to "sh". On MS-DOS and OS/2 systems, the shell is the normal
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command processor.
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| <m> shell-command
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<m> represents any mark letter. Pipes a section of the input
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file to the given shell command. The section of the file to be
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piped is between the first line on the current screen and the
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position marked by the letter. <m> may also be ^ or $ to indi-
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cate beginning or end of file respectively. If <m> is . or new-
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line, the current screen is piped.
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s filename
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Save the input to a file. This only works if the input is a
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pipe, not an ordinary file.
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[1mOPTIONS[0m
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Command line options are described below. Most options may be changed
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while [4mless[24m is running, via the "-" command.
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Most options may be given in one of two forms: either a dash followed
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by a single letter, or two dashes followed by a long option name. A
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long option name may be abbreviated as long as the abbreviation is
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unambiguous. For example, --quit-at-eof may be abbreviated --quit, but
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not --qui, since both --quit-at-eof and --quiet begin with --qui. Some
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long option names are in uppercase, such as --QUIT-AT-EOF, as distinct
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from --quit-at-eof. Such option names need only have their first let-
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ter capitalized; the remainder of the name may be in either case. For
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example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.
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Options are also taken from the environment variable "LESS". For exam-
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ple, to avoid typing "less -options ..." each time [4mless[24m is invoked, you
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might tell [4mcsh:[0m
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setenv LESS "-options"
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or if you use [4msh:[0m
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LESS="-options"; export LESS
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On MS-DOS, you don't need the quotes, but you should replace any per-
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cent signs in the options string by double percent signs.
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The environment variable is parsed before the command line, so command
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||
line options override the LESS environment variable. If an option
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||
appears in the LESS variable, it can be reset to its default value on
|
||
the command line by beginning the command line option with "-+".
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||
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||
For options like -P or -D which take a following string, a dollar sign
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($) must be used to signal the end of the string. For example, to set
|
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two -D options on MS-DOS, you must have a dollar sign between them,
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like this:
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LESS="-Dn9.1$-Ds4.1"
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-? or --help
|
||
This option displays a summary of the commands accepted by [4mless[0m
|
||
(the same as the h command). (Depending on how your shell
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interprets the question mark, it may be necessary to quote the
|
||
question mark, thus: "-\?".)
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-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 dis-
|
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played screen (except for repeated searches invoked by the n or
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||
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.
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||
|
||
-A or --SEARCH-SKIP-SCREEN
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||
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.
|
||
|
||
-b[4mn[24m or --buffers=[4mn[0m
|
||
Specifies the amount of buffer space [4mless[24m will use for each
|
||
file, in units of kilobytes (1024 bytes). By default 64K of
|
||
buffer space is used for each file (unless the file is a pipe;
|
||
see the -B option). The -b option specifies instead that [4mn[0m
|
||
kilobytes of buffer space should be used for each file. If [4mn[24m is
|
||
-1, buffer space is unlimited; that is, the entire file can be
|
||
read into memory.
|
||
|
||
-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 allo-
|
||
cated. The -B option disables this automatic allocation of buf-
|
||
fers for pipes, so that only 64K (or the amount of space speci-
|
||
fied 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.
|
||
|
||
-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.
|
||
|
||
-C or --CLEAR-SCREEN
|
||
Same as -c, for compatibility with older versions of [4mless.[0m
|
||
|
||
-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 [4mless[24m on a
|
||
dumb terminal.
|
||
|
||
-D[1mx[4m[22mcolor[24m or --color=[1mx[4m[22mcolor[0m
|
||
[MS-DOS only] Sets the color of the text displayed. [1mx [22mis a sin-
|
||
gle character which selects the type of text whose color is
|
||
being set: n=normal, s=standout, d=bold, u=underlined, k=blink.
|
||
[4mcolor[24m 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 [4mN[24m is the same as
|
||
[4mN.M[24m, where [4mM[24m is the normal background color.
|
||
|
||
|
||
-e or --quit-at-eof
|
||
Causes [4mless[24m to automatically exit the second time it reaches
|
||
end-of-file. By default, the only way to exit [4mless[24m is via the
|
||
"q" command.
|
||
|
||
-E or --QUIT-AT-EOF
|
||
Causes [4mless[24m to automatically exit the first time it reaches end-
|
||
of-file.
|
||
|
||
-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 warn-
|
||
ing message when a binary file is opened. By default, [4mless[24m will
|
||
refuse to open non-regular files. Note that some operating sys-
|
||
tems will not allow directories to be read, even if -f is set.
|
||
|
||
-F or --quit-if-one-screen
|
||
Causes [4mless[24m to automatically exit if the entire file can be dis-
|
||
played on the first screen.
|
||
|
||
-g or --hilite-search
|
||
Normally, [4mless[24m will highlight ALL strings which match the last
|
||
search command. The -g option changes this behavior to high-
|
||
light only the particular string which was found by the last
|
||
search command. This can cause [4mless[24m to run somewhat faster than
|
||
the default.
|
||
|
||
-G or --HILITE-SEARCH
|
||
The -G option suppresses all highlighting of strings found by
|
||
search commands.
|
||
|
||
-h[4mn[24m or --max-back-scroll=[4mn[0m
|
||
Specifies a maximum number of lines to scroll backward. If it
|
||
is necessary to scroll backward more than [4mn[24m lines, the screen is
|
||
repainted in a forward direction instead. (If the terminal does
|
||
not have the ability to scroll backward, -h0 is implied.)
|
||
|
||
-i or --ignore-case
|
||
Causes searches to ignore case; that is, uppercase and lowercase
|
||
are considered identical. This option is ignored if any upper-
|
||
case letters appear in the search pattern; in other words, if a
|
||
pattern contains uppercase letters, then that search does not
|
||
ignore case.
|
||
|
||
-I or --IGNORE-CASE
|
||
Like -i, but searches ignore case even if the pattern contains
|
||
uppercase letters.
|
||
|
||
-j[4mn[24m or --jump-target=[4mn[0m
|
||
Specifies a line on the screen where the "target" line is to be
|
||
positioned. The target line is the line specified by any com-
|
||
mand 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 speci-
|
||
fied 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 rel-
|
||
ative to the bottom of the screen: the bottom line on the screen
|
||
is -1, the second to the bottom is -2, and so on. Alternately,
|
||
the screen line may be specified as a fraction of the height of
|
||
the screen, starting with a decimal point: .5 is in the middle
|
||
of the screen, .3 is three tenths down from the first line, and
|
||
so on. If the line is specified as a fraction, the actual line
|
||
number is recalculated if the terminal window is resized, so
|
||
that the target line remains at the specified fraction of the
|
||
screen height. If any form of the -j option is used, forward
|
||
searches begin at the line immediately after the target line,
|
||
and backward searches begin at the target line, unless changed
|
||
by -a or -A. For example, if "-j4" is used, the target line is
|
||
the fourth line on the screen, so forward searches begin at the
|
||
fifth line on the screen.
|
||
|
||
-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.
|
||
|
||
-k[4mfilename[24m or --lesskey-file=[4mfilename[0m
|
||
Causes [4mless[24m to open and interpret the named file as a [4mlesskey[0m
|
||
(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 [4mlesskey[24m file.
|
||
|
||
-K or --quit-on-intr
|
||
Causes [4mless[24m to exit immediately (with status 2) when an inter-
|
||
rupt character (usually ^C) is typed. Normally, an interrupt
|
||
character causes [4mless[24m 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.
|
||
|
||
-L or --no-lessopen
|
||
Ignore the LESSOPEN environment variable (see the INPUT PRE-
|
||
PROCESSOR section below). This option can be set from within
|
||
[4mless[24m, but it will apply only to files opened subsequently, not
|
||
to the file which is currently open.
|
||
|
||
-m or --long-prompt
|
||
Causes [4mless[24m to prompt verbosely (like [4mmore[24m), with the percent
|
||
into the file. By default, [4mless[24m prompts with a colon.
|
||
|
||
-M or --LONG-PROMPT
|
||
Causes [4mless[24m to prompt even more verbosely than [4mmore.[0m
|
||
|
||
-n or --line-numbers
|
||
Suppresses line numbers. The default (to use line numbers) may
|
||
cause [4mless[24m 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).
|
||
|
||
-N or --LINE-NUMBERS
|
||
Causes a line number to be displayed at the beginning of each
|
||
line in the display.
|
||
|
||
-o[4mfilename[24m or --log-file=[4mfilename[0m
|
||
Causes [4mless[24m 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, [4mless[24m will ask for
|
||
confirmation before overwriting it.
|
||
|
||
-O[4mfilename[24m or --LOG-FILE=[4mfilename[0m
|
||
The -O option is like -o, but it will overwrite an existing file
|
||
without asking for confirmation.
|
||
|
||
If no log file has been specified, the -o and -O options can be
|
||
used from within [4mless[24m 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 [4mless.[0m
|
||
|
||
-p[4mpattern[24m or --pattern=[4mpattern[0m
|
||
The -p option on the command line is equivalent to specifying
|
||
+/[4mpattern[24m; that is, it tells [4mless[24m to start at the first occur-
|
||
rence of [4mpattern[24m in the file.
|
||
|
||
-P[4mprompt[24m or --prompt=[4mprompt[0m
|
||
Provides a way to tailor the three prompt styles to your own
|
||
preference. This option would normally be put in the LESS envi-
|
||
ronment variable, rather than being typed in with each [4mless[24m com-
|
||
mand. 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.
|
||
|
||
-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.
|
||
|
||
-Q or --QUIET or --SILENT
|
||
Causes totally "quiet" operation: the terminal bell is never
|
||
rung.
|
||
|
||
-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, [4mless[24m 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 dis-
|
||
play problems may result, such as long lines being split in the
|
||
wrong place.
|
||
|
||
-R or --RAW-CONTROL-CHARS
|
||
Like -r, but only ANSI "color" escape sequences are output in
|
||
"raw" form. Unlike -r, the screen appearance is maintained cor-
|
||
rectly in most cases. ANSI "color" escape sequences are
|
||
sequences of the form:
|
||
|
||
ESC [ ... m
|
||
|
||
where the "..." is zero or more color specification characters
|
||
For the purpose of keeping track of screen appearance, ANSI
|
||
color escape sequences are assumed to not move the cursor. You
|
||
can make [4mless[24m 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 [4mless[24m 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.
|
||
|
||
-s or --squeeze-blank-lines
|
||
Causes consecutive blank lines to be squeezed into a single
|
||
blank line. This is useful when viewing [4mnroff[24m output.
|
||
|
||
-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.
|
||
|
||
-t[4mtag[24m or --tag=[4mtag[0m
|
||
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 [4mctags[24m (1)
|
||
or an equivalent command. If the environment variable LESSGLOB-
|
||
ALTAGS is set, it is taken to be the name of a command compati-
|
||
ble with [4mglobal[24m (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 [4mless[24m (using the -
|
||
command) as a way of examining a new file. The command ":t" is
|
||
equivalent to specifying -t from within [4mless.[0m
|
||
|
||
-T[4mtagsfile[24m or --tag-file=[4mtagsfile[0m
|
||
Specifies a tags file to be used instead of "tags".
|
||
|
||
-u or --underline-special
|
||
Causes backspaces and carriage returns to be treated as print-
|
||
able characters; that is, they are sent to the terminal when
|
||
they appear in the input.
|
||
|
||
-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.
|
||
|
||
By default, if neither -u nor -U is given, backspaces which
|
||
appear adjacent to an underscore character are treated spe-
|
||
cially: 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 bold-
|
||
face 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 under-
|
||
lined can be searched for if neither -u nor -U is in effect.
|
||
|
||
-V or --version
|
||
Displays the version number of [4mless.[0m
|
||
|
||
-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 imme-
|
||
diately 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 move-
|
||
ment. The entire line is highlighted, unless the -J option is
|
||
in effect, in which case only the status column is highlighted.
|
||
|
||
-W or --HILITE-UNREAD
|
||
Like -w, but temporarily highlights the first new line after any
|
||
forward movement command larger than one line.
|
||
|
||
-x[4mn[24m,... or --tabs=[4mn[24m,...
|
||
Sets tab stops. If only one [4mn[24m is specified, tab stops are set
|
||
at multiples of [4mn[24m. If multiple values separated by commas are
|
||
specified, tab stops are set at those positions, and then con-
|
||
tinue with the same spacing as the last two. For example,
|
||
[4m-x9,17[24m will set tabs at positions 9, 17, 25, 33, etc. The
|
||
default for [4mn[24m is 8.
|
||
|
||
-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 clear-
|
||
ing the screen.
|
||
|
||
-y[4mn[24m or --max-forw-scroll=[4mn[0m
|
||
Specifies a maximum number of lines to scroll forward. If it is
|
||
necessary to scroll forward more than [4mn[24m 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.
|
||
|
||
-[z][4mn[24m or --window=[4mn[0m
|
||
Changes the default scrolling window size to [4mn[24m 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 compati-
|
||
bility with some versions of [4mmore.[24m If the number [4mn[24m is negative,
|
||
it indicates [4mn[24m lines less than the current screen size. For
|
||
example, if the screen is 24 lines, [4m-z-4[24m sets the scrolling win-
|
||
dow to 20 lines. If the screen is resized to 40 lines, the
|
||
scrolling window automatically changes to 36 lines.
|
||
|
||
-[4m"cc[24m or --quotes=[4mcc[0m
|
||
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).
|
||
|
||
-~ 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.
|
||
|
||
-# or --shift
|
||
Specifies the default number of positions to scroll horizontally
|
||
in the RIGHTARROW and LEFTARROW commands. If the number speci-
|
||
fied is zero, it sets the default number of positions to one
|
||
half of the screen width. Alternately, the number may be speci-
|
||
fied 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 speci-
|
||
fied 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.
|
||
|
||
--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.
|
||
|
||
--follow-name
|
||
Normally, if the input file is renamed while an F command is
|
||
executing, [4mless[24m will continue to display the contents of the
|
||
original file despite its name change. If --follow-name is
|
||
specified, during an F command [4mless[24m 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), [4mless[24m will display the contents of that new file.
|
||
|
||
-- A command line argument of "--" marks the end of option argu-
|
||
ments. Any arguments following this are interpreted as file-
|
||
names. This can be useful when viewing a file whose name begins
|
||
with a "-" or "+".
|
||
|
||
+ If a command line option begins with [1m+[22m, the remainder of that
|
||
option is taken to be an initial command to [4mless.[24m For example,
|
||
+G tells [4mless[24m 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 ini-
|
||
tial command for every file.
|
||
|
||
|
||
[1mLINE EDITING[0m
|
||
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), cer-
|
||
tain 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.
|
||
|
||
LEFTARROW [ ESC-h ]
|
||
Move the cursor one space to the left.
|
||
|
||
RIGHTARROW [ ESC-l ]
|
||
Move the cursor one space to the right.
|
||
|
||
^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
|
||
(That is, CONTROL and LEFTARROW simultaneously.) Move the cur-
|
||
sor one word to the left.
|
||
|
||
^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
|
||
(That is, CONTROL and RIGHTARROW simultaneously.) Move the cur-
|
||
sor one word to the right.
|
||
|
||
HOME [ ESC-0 ]
|
||
Move the cursor to the beginning of the line.
|
||
|
||
END [ ESC-$ ]
|
||
Move the cursor to the end of the line.
|
||
|
||
BACKSPACE
|
||
Delete the character to the left of the cursor, or cancel the
|
||
command if the command line is empty.
|
||
|
||
DELETE or [ ESC-x ]
|
||
Delete the character under the cursor.
|
||
|
||
^BACKSPACE [ ESC-BACKSPACE ]
|
||
(That is, CONTROL and BACKSPACE simultaneously.) Delete the
|
||
word to the left of the cursor.
|
||
|
||
^DELETE [ ESC-X or ESC-DELETE ]
|
||
(That is, CONTROL and DELETE simultaneously.) Delete the word
|
||
under the cursor.
|
||
|
||
UPARROW [ ESC-k ]
|
||
Retrieve the previous command line.
|
||
|
||
DOWNARROW [ ESC-j ]
|
||
Retrieve the next command line.
|
||
|
||
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 "\" is
|
||
appended.) The environment variable LESSSEPARATOR can be used
|
||
to specify a different character to append to a directory name.
|
||
|
||
BACKTAB [ ESC-TAB ]
|
||
Like, TAB, but cycles in the reverse direction thru the matching
|
||
filenames.
|
||
|
||
^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).
|
||
|
||
^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 char-
|
||
acter in Unix to something other than ^U, that character is used
|
||
instead of ^U.
|
||
|
||
^G Delete the entire command line and return to the main prompt.
|
||
|
||
|
||
[1mKEY BINDINGS[0m
|
||
You may define your own [4mless[24m commands by using the program [4mlesskey[24m (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 [4mlesskey[24m to
|
||
change the line-editing keys (see LINE EDITING), and to set environment
|
||
variables. If the environment variable LESSKEY is set, [4mless[24m uses that
|
||
as the name of the lesskey file. Otherwise, [4mless[24m looks in a standard
|
||
place for the lesskey file: On Unix systems, [4mless[24m looks for a lesskey
|
||
file called "$HOME/.less". On MS-DOS and Windows systems, [4mless[24m looks
|
||
for a lesskey file called "$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, [4mless[24m 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 [4mlesskey[24m manual page for more
|
||
details.
|
||
|
||
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,
|
||
[4mless[24m uses that as the name of the system-wide lesskey file. Otherwise,
|
||
[4mless[24m 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 [4mless[24m 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:\_sys-
|
||
less. On OS/2 systems, the system-wide lesskey file is c:\sysless.ini.
|
||
|
||
|
||
[1mINPUT PREPROCESSOR[0m
|
||
You may define an "input preprocessor" for [4mless.[24m Before [4mless[24m 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 sim-
|
||
ply an executable program (or shell script), which writes the contents
|
||
of the file to a different file, called the replacement file. The con-
|
||
tents of the replacement file are then displayed in place of the con-
|
||
tents of the original file. However, it will appear to the user as if
|
||
the original file is opened; that is, [4mless[24m will display the original
|
||
filename as the name of the current file.
|
||
|
||
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 replace-
|
||
ment filename, [4mless[24m uses the original file, as normal. The input pre-
|
||
processor 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.
|
||
|
||
When [4mless[24m closes a file opened in such a way, it will call another pro-
|
||
gram, 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 orig-
|
||
inal 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.
|
||
|
||
For example, on many Unix systems, these two scripts will allow you to
|
||
keep files in compressed format, but still let [4mless[24m view them directly:
|
||
|
||
lessopen.sh:
|
||
#! /bin/sh
|
||
case "$1" in
|
||
*.Z) uncompress -
|
||
if [ -s /tmp/less.$$ ]; then
|
||
echo /tmp/less.$$
|
||
else
|
||
rm -f /tmp/less.$$
|
||
fi
|
||
;;
|
||
esac
|
||
|
||
lessclose.sh:
|
||
#! /bin/sh
|
||
rm $2
|
||
|
||
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.
|
||
|
||
It is also possible to set up an input preprocessor to pipe the file
|
||
data directly to [4mless,[24m rather than putting the data into a replacement
|
||
file. This avoids the need to decompress the entire file before start-
|
||
ing 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 replace-
|
||
ment 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 replace-
|
||
ment file and [4mless[24m 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.
|
||
|
||
For example, on many Unix systems, this script will work like the pre-
|
||
vious example scripts:
|
||
|
||
lesspipe.sh:
|
||
#! /bin/sh
|
||
case "$1" in
|
||
*.Z) uncompress -c $1 2>/dev/null
|
||
;;
|
||
esac
|
||
|
||
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 "-".
|
||
|
||
For compatibility with previous versions of [4mless,[24m the input preproces-
|
||
sor or pipe is not used if [4mless[24m 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 charac-
|
||
ters of LESSOPEN are vertical bar and 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.
|
||
|
||
|
||
[1mNATIONAL CHARACTER SETS[0m
|
||
There are three types of characters in the input file:
|
||
|
||
normal characters
|
||
can be displayed directly to the screen.
|
||
|
||
control characters
|
||
should not be displayed directly, but are expected to be found
|
||
in ordinary text files (such as backspace and tab).
|
||
|
||
binary characters
|
||
should not be displayed directly and are not expected to be
|
||
found in text files.
|
||
|
||
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:
|
||
|
||
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.
|
||
|
||
iso8859
|
||
Selects an ISO 8859 character set. This is the same as ASCII,
|
||
except characters between 160 and 255 are treated as normal
|
||
characters.
|
||
|
||
latin1 Same as iso8859.
|
||
|
||
latin9 Same as iso8859.
|
||
|
||
dos Selects a character set appropriate for MS-DOS.
|
||
|
||
ebcdic Selects an EBCDIC character set.
|
||
|
||
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.
|
||
|
||
koi8-r Selects a Russian character set.
|
||
|
||
next Selects a character set appropriate for NeXT computers.
|
||
|
||
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.
|
||
|
||
windows
|
||
Selects a character set appropriate for Microsoft Windows (cp
|
||
1251).
|
||
|
||
In rare cases, it may be desired to tailor [4mless[24m to use a character set
|
||
other than the ones definable by LESSCHARSET. In this case, the envi-
|
||
ronment 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 num-
|
||
ber 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 char-
|
||
acter set.)
|
||
|
||
This table shows the value of LESSCHARDEF which is equivalent to each
|
||
of the possible values for LESSCHARSET:
|
||
|
||
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
|
||
|
||
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.
|
||
|
||
If that string is not found, but your system supports the [4msetlocale[0m
|
||
interface, [4mless[24m will use setlocale to determine the character set.
|
||
setlocale is controlled by setting the LANG or LC_CTYPE environment
|
||
variables.
|
||
|
||
Finally, if the [4msetlocale[24m interface is also not available, the default
|
||
character set is latin1.
|
||
|
||
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 char-
|
||
acter 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.
|
||
|
||
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., unas-
|
||
signed code points). Its default value is "<U+%04lX>". Note that
|
||
LESSUTFBINFMT and LESSBINFMT share their display attribute setting
|
||
("*x") so specifying one will affect both; LESSUTFBINFMT is read after
|
||
LESSBINFMT so its setting, if any, will have priority. Problematic
|
||
octets in a UTF-8 file (octets of a truncated sequence, octets of a
|
||
complete but non-shortest form sequence, illegal octets, and stray
|
||
trailing octets) are displayed individually using LESSBINFMT so as to
|
||
facilitate diagnostic of how the UTF-8 file is ill-formed.
|
||
|
||
|
||
[1mPROMPTS[0m
|
||
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 ordi-
|
||
nary user need not understand the details of constructing personalized
|
||
prompt strings.
|
||
|
||
A percent sign followed by a single character is expanded according to
|
||
what the following character is:
|
||
|
||
%b[4mX[24m Replaced by the byte offset into the current input file. The b
|
||
is followed by a single character (shown as [4mX[24m above) which spec-
|
||
ifies the line whose byte offset is to be used. If the charac-
|
||
ter 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 bot-
|
||
tom 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.
|
||
|
||
%B Replaced by the size of the current input file.
|
||
|
||
%c Replaced by the column number of the text appearing in the first
|
||
column of the screen.
|
||
|
||
%d[4mX[24m Replaced by the page number of a line in the input file. The
|
||
line to be used is determined by the [4mX[24m, as with the %b option.
|
||
|
||
%D Replaced by the number of pages in the input file, or equiva-
|
||
lently, the page number of the last line in the input file.
|
||
|
||
%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.
|
||
|
||
%f Replaced by the name of the current input file.
|
||
|
||
%F Replaced by the last component of the name of the current input
|
||
file.
|
||
|
||
%i Replaced by the index of the current file in the list of input
|
||
files.
|
||
|
||
%l[4mX[24m Replaced by the line number of a line in the input file. The
|
||
line to be used is determined by the [4mX[24m, as with the %b option.
|
||
|
||
%L Replaced by the line number of the last line in the input file.
|
||
|
||
%m Replaced by the total number of input files.
|
||
|
||
%p[4mX[24m Replaced by the percent into the current input file, based on
|
||
byte offsets. The line used is determined by the [4mX[24m as with the
|
||
%b option.
|
||
|
||
%P[4mX[24m Replaced by the percent into the current input file, based on
|
||
line numbers. The line used is determined by the [4mX[24m as with the
|
||
%b option.
|
||
|
||
%s Same as %B.
|
||
|
||
%t Causes any trailing spaces to be removed. Usually used at the
|
||
end of the string, but may appear anywhere.
|
||
|
||
%x Replaced by the name of the next input file in the list.
|
||
|
||
If any item is unknown (for example, the file size if input is a pipe),
|
||
a question mark is printed instead.
|
||
|
||
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 evalu-
|
||
ated. 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:
|
||
|
||
?a True if any characters have been included in the prompt so far.
|
||
|
||
?b[4mX[24m True if the byte offset of the specified line is known.
|
||
|
||
?B True if the size of current input file is known.
|
||
|
||
?c True if the text is horizontally shifted (%c is not zero).
|
||
|
||
?d[4mX[24m True if the page number of the specified line is known.
|
||
|
||
?e True if at end-of-file.
|
||
|
||
?f True if there is an input filename (that is, if input is not a
|
||
pipe).
|
||
|
||
?l[4mX[24m True if the line number of the specified line is known.
|
||
|
||
?L True if the line number of the last line in the file is known.
|
||
|
||
?m True if there is more than one input file.
|
||
|
||
?n True if this is the first prompt in a new input file.
|
||
|
||
?p[4mX[24m True if the percent into the current input file, based on byte
|
||
offsets, of the specified line is known.
|
||
|
||
?P[4mX[24m True if the percent into the current input file, based on line
|
||
numbers, of the specified line is known.
|
||
|
||
?s Same as "?B".
|
||
|
||
?x True if there is a next input file (that is, if the current
|
||
input file is not the last one).
|
||
|
||
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.
|
||
|
||
Some examples:
|
||
|
||
?f%f:Standard input.
|
||
|
||
This prompt prints the filename, if known; otherwise the string "Stan-
|
||
dard input".
|
||
|
||
?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
|
||
|
||
This prompt would print the filename, if known. The filename is fol-
|
||
lowed 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.
|
||
|
||
?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t
|
||
|
||
This prints the filename if this is the first prompt in a file, fol-
|
||
lowed 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 refer-
|
||
ence, here are the defaults for the other two prompts (-m and -M
|
||
respectively). Each is broken into two lines here for readability
|
||
only.
|
||
|
||
?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
|
||
?pB%pB\%:byte %bB?s/%s...%t
|
||
|
||
?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
|
||
byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
|
||
|
||
And here is the default message produced by the = command:
|
||
|
||
?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
|
||
byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
|
||
|
||
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:
|
||
|
||
%E ?lm+%lm. %f
|
||
|
||
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.
|
||
|
||
|
||
[1mSECURITY[0m
|
||
When the environment variable LESSSECURE is set to 1, [4mless[24m runs in a
|
||
"secure" mode. This means these features are disabled:
|
||
|
||
! the shell command
|
||
|
||
| the pipe command
|
||
|
||
:e the examine command.
|
||
|
||
v the editing command
|
||
|
||
s -o log files
|
||
|
||
-k use of lesskey files
|
||
|
||
-t use of tags files
|
||
|
||
metacharacters in filenames, such as *
|
||
|
||
filename completion (TAB, ^L)
|
||
|
||
Less can also be compiled to be permanently in "secure" mode.
|
||
|
||
|
||
[1mCOMPATIBILITY WITH MORE[0m
|
||
If the environment variable LESS_IS_MORE is set to 1, or if the program
|
||
is invoked via a file link named "more", [4mless[24m behaves (mostly) in con-
|
||
formance with the POSIX "more" command specification. In this mode,
|
||
less behaves differently in these ways:
|
||
|
||
The -e option works differently. If the -e option is not set, [4mless[0m
|
||
behaves as if the -E option were set. If the -e option is set, [4mless[0m
|
||
behaves as if the -e and -F options were set.
|
||
|
||
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.
|
||
|
||
The -n option acts like the -z option. The normal behavior of the -n
|
||
option is unavailable in this mode.
|
||
|
||
The parameter to the -p option is taken to be a [4mless[24m command rather
|
||
than a search pattern.
|
||
|
||
The LESS environment variable is ignored, and the MORE environment
|
||
variable is used in its place.
|
||
|
||
|
||
[1mENVIRONMENT VARIABLES[0m
|
||
Environment variables may be specified either in the system environment
|
||
as usual, or in a [4mlesskey[24m (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.
|
||
|
||
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.)
|
||
|
||
EDITOR The name of the editor (used for the v command).
|
||
|
||
HOME Name of the user's home directory (used to find a lesskey file
|
||
on Unix and OS/2 systems).
|
||
|
||
HOMEDRIVE, HOMEPATH
|
||
Concatenation of the HOMEDRIVE and HOMEPATH environment vari-
|
||
ables is the name of the user's home directory if the HOME vari-
|
||
able is not set (only in the Windows version).
|
||
|
||
INIT Name of the user's init directory (used to find a lesskey file
|
||
on OS/2 systems).
|
||
|
||
LANG Language for determining the character set.
|
||
|
||
LC_CTYPE
|
||
Language for determining the character set.
|
||
|
||
LESS Options which are passed to [4mless[24m automatically.
|
||
|
||
LESSANSIENDCHARS
|
||
Characters which may end an ANSI color escape sequence (default
|
||
"m").
|
||
|
||
LESSANSIMIDCHARS
|
||
Characters which may appear between the ESC character and the
|
||
end character in an ANSI color escape sequence (default
|
||
"0123456789;[?!"'#%()*+ ".
|
||
|
||
LESSBINFMT
|
||
Format for displaying non-printable, non-control characters.
|
||
|
||
LESSCHARDEF
|
||
Defines a character set.
|
||
|
||
LESSCHARSET
|
||
Selects a predefined character set.
|
||
|
||
LESSCLOSE
|
||
Command line to invoke the (optional) input-postprocessor.
|
||
|
||
LESSECHO
|
||
Name of the lessecho program (default "lessecho"). The lessecho
|
||
program is needed to expand metacharacters, such as * and ?, in
|
||
filenames on Unix systems.
|
||
|
||
LESSEDIT
|
||
Editor prototype string (used for the v command). See discus-
|
||
sion under PROMPTS.
|
||
|
||
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 [4mglobal[0m
|
||
(1) command. If not set, global tags are not used.
|
||
|
||
LESSHISTFILE
|
||
Name of the history file used to remember search commands and
|
||
shell commands between invocations of [4mless.[24m If set to "-" or
|
||
"/dev/null", a history file is not used. The default is
|
||
"$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and
|
||
Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini"
|
||
on OS/2 systems.
|
||
|
||
LESSHISTSIZE
|
||
The maximum number of commands to save in the history file. The
|
||
default is 100.
|
||
|
||
LESSKEY
|
||
Name of the default lesskey(1) file.
|
||
|
||
LESSKEY_SYSTEM
|
||
Name of the default system-wide lesskey(1) file.
|
||
|
||
LESSMETACHARS
|
||
List of characters which are considered "metacharacters" by the
|
||
shell.
|
||
|
||
LESSMETAESCAPE
|
||
Prefix which less will add before each metacharacter in a com-
|
||
mand sent to the shell. If LESSMETAESCAPE is an empty string,
|
||
commands containing metacharacters will not be passed to the
|
||
shell.
|
||
|
||
LESSOPEN
|
||
Command line to invoke the (optional) input-preprocessor.
|
||
|
||
LESSSECURE
|
||
Runs less in "secure" mode. See discussion under SECURITY.
|
||
|
||
LESSSEPARATOR
|
||
String to be appended to a directory name in filename comple-
|
||
tion.
|
||
|
||
LESSUTFBINFMT
|
||
Format for displaying non-printable Unicode code points.
|
||
|
||
LESS_IS_MORE
|
||
Emulate the [4mmore[24m (1) command.
|
||
|
||
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.)
|
||
|
||
PATH User's search path (used to find a lesskey file on MS-DOS and
|
||
OS/2 systems).
|
||
|
||
SHELL The shell used to execute the ! command, as well as to expand
|
||
filenames.
|
||
|
||
TERM The type of terminal on which [4mless[24m is being run.
|
||
|
||
VISUAL The name of the editor (used for the v command).
|
||
|
||
|
||
[1mSEE ALSO[0m
|
||
lesskey(1)
|
||
|
||
|
||
[1mCOPYRIGHT[0m
|
||
Copyright (C) 1984-2011 Mark Nudelman
|
||
|
||
less is part of the GNU project and is free software. You can redis-
|
||
tribute it and/or modify it under the terms of either (1) the GNU Gen-
|
||
eral 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.
|
||
|
||
less is distributed in the hope that it will be useful, but WITHOUT ANY
|
||
WARRANTY; without even the implied warranty of MERCHANTABILITY or FIT-
|
||
NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
||
more details.
|
||
|
||
|
||
[1mAUTHOR[0m
|
||
Mark Nudelman <markn@greenwoodsoftware.com>
|
||
Send bug reports or comments to the above address or to bug-
|
||
less@gnu.org.
|
||
See http://www.greenwoodsoftware.com/less/bugs.html for the latest list
|
||
of known bugs in less.
|
||
For more information, see the less homepage at
|
||
http://www.greenwoodsoftware.com/less.
|
||
|
||
|
||
|
||
Version 444: 09 Jun 2011 LESS(1)
|