lesskey(1) — Linux manual page


LESSKEY(1)               General Commands Manual              LESSKEY(1)

NAME         top

       lesskey - customize key bindings for less

SYNOPSIS (deprecated)         top

       lesskey [-o output] [--] [input]
       lesskey [--output=output] [--] [input]
       lesskey -V
       lesskey --version

SCOPE         top

       This document describes the format of the lesskey source file,
       which is used by less version 582 and later.  In previous
       versions of less, a separate program called lesskey was used to
       compile the lesskey source file into a format understood by less.
       This compilation step is no longer required and the lesskey
       program is therefore deprecated, although the file format remains
       supported by less itself.

DESCRIPTION         top

       A lesskey file specifies a set of key bindings and environment
       variables to be used by subsequent invocations of less.

FILE FORMAT         top

       The input file consists of one or more sections.  Each section
       starts with a line that identifies the type of section.  Possible
       sections are:

              Customizes command key bindings.

              Customizes line-editing key bindings.

       #env   Defines environment variables.

       Blank lines and lines which start with a hash mark (#) are
       ignored, except as noted below.


       The command section begins with the line


       If the command section is the first section in the file, this
       line may be omitted.  The command section consists of lines of
       the form:

            string <whitespace> action [extra-string] <newline>

       Whitespace is any sequence of one or more spaces and/or tabs.
       The string is the command key(s) which invoke the action.  The
       string may be a single command key, or a sequence of up to 15
       keys.  The action is the name of the less action, from the list
       below.  The characters in the string may appear literally, or be
       prefixed by a caret to indicate a control key.  A backslash
       followed by one to three octal digits may be used to specify a
       character by its octal value.  A backslash followed by certain
       characters specifies input characters as follows:
            \b   BACKSPACE   (0x08)
            \e   ESCAPE      (0x1B)
            \n   NEWLINE     (0x0A)
            \r   RETURN      (0x0D)
            \t   TAB         (0x09)

            \k followed by a single character represents the char(s)
            produced when one of these keys is pressed:
            \kb   BACKSPACE (the BACKSPACE key)
            \kB   ctrl-BACKSPACE
            \kd   DOWN ARROW
            \kD   PAGE DOWN
            \ke   END
            \kh   HOME
            \ki   INSERT
            \kl   LEFT ARROW
            \kL   ctrl-LEFT ARROW
            \kr   RIGHT ARROW
            \kR   ctrl-RIGHT ARROW
            \kt   BACKTAB
            \ku   UP ARROW
            \kU   PAGE UP
            \kx   DELETE
            \kX   ctrl-DELETE
            \k1   F1

            A backslash followed by any other character indicates that
            character is to be taken literally.  Characters which must
            be preceded by backslash include caret, space, tab, hash
            mark and the backslash itself.

            An action may be followed by an "extra" string.  When such a
            command is entered while running less, the action is
            performed, and then the extra string is parsed, just as if
            it were typed in to less.  This feature can be used in
            certain cases to extend the functionality of a command.  For
            example, see the "{" and ":t" commands in the example below.
            The extra string has a special meaning for the "quit"
            action: when less quits, the first character of the extra
            string is used as its exit status.

EXAMPLE         top

       The following input file describes the set of default command
       keys used by less.  Documentation on each command can be found in
       the man page, under the key sequence which invokes the command.

            \r         forw-line
            \n         forw-line
            e          forw-line
            j          forw-line
            \kd        forw-line
            ^E         forw-line
            ^N         forw-line
            k          back-line
            y          back-line
            ^Y         back-line
            ^K         back-line
            ^P         back-line
            J          forw-line-force
            K          back-line-force
            Y          back-line-force
            d          forw-scroll
            ^D         forw-scroll
            u          back-scroll
            ^U         back-scroll
            \40        forw-screen
            f          forw-screen
            ^F         forw-screen
            ^V         forw-screen
            \kD        forw-screen
            b          back-screen
            ^B         back-screen
            \ev        back-screen
            \kU        back-screen
            z          forw-window
            w          back-window
            \e\40      forw-screen-force
            F          forw-forever
            \eF        forw-until-hilite
            R          repaint-flush
            r          repaint
            ^R         repaint
            ^L         repaint
            \eu        undo-hilite
            \eU        clear-search
            g          goto-line
            \kh        goto-line
            <          goto-line
            \e<        goto-line
            p          percent
            %          percent
            \e[        left-scroll
            \e]        right-scroll
            \e(        left-scroll
            \e)        right-scroll
            \kl        left-scroll
            \kr        right-scroll
            \e{        no-scroll
            \e}        end-scroll
            {          forw-bracket {}
            }          back-bracket {}
            (          forw-bracket ()
            )          back-bracket ()
            [          forw-bracket []
            ]          back-bracket []
            \e^F       forw-bracket
            \e^B       back-bracket
            G          goto-end
            \e>        goto-end
            >          goto-end
            \ke        goto-end
            \eG        goto-end-buffered
            =          status
            ^G         status
            :f         status
            /          forw-search
            ?          back-search
            \e/        forw-search *
            \e?        back-search *
            n          repeat-search
            \en        repeat-search-all
            N          reverse-search
            \eN        reverse-search-all
            &          filter
            m          set-mark
            M          set-mark-bottom
            \em        clear-mark
            '          goto-mark
            ^X^X       goto-mark
            E          examine
            :e         examine
            ^X^V       examine
            :n         next-file
            :p         prev-file
            t          next-tag
            T          prev-tag
            :x         index-file
            :d         remove-file
            -          toggle-option
            :t         toggle-option t
            s          toggle-option o
                       ## Use a long option name by starting the
                       ## extra string with ONE dash; eg:
                       ##   s toggle-option -log-file\n
            _          display-option
            |          pipe
            v          visual
            !          shell
            #          pshell
            +          firstcmd
            H          help
            h          help
            V          version
            0          digit
            1          digit
            2          digit
            3          digit
            4          digit
            5          digit
            6          digit
            7          digit
            8          digit
            9          digit
            q          quit
            Q          quit
            :q         quit
            :Q         quit
            ZZ         quit

PRECEDENCE         top

       Commands specified by lesskey take precedence over the default
       commands.  A default command key may be disabled by including it
       in the input file with the action "invalid".  Alternatively, a
       key may be defined to do nothing by using the action "noaction".
       "noaction" is similar to "invalid", but less will give an error
       beep for an "invalid" command, but not for a "noaction" command.
       In addition, ALL default commands may be disabled by adding this
       control line to the input file:


       This will cause all default commands to be ignored.  The #stop
       line should be the last line in that section of the file.

       Be aware that #stop can be dangerous.  Since all default commands
       are disabled, you must provide sufficient commands before the
       #stop line to enable all necessary actions.  For example, failure
       to provide a "quit" command can lead to frustration.


       The line-editing section begins with the line:


       This section specifies new key bindings for the line editing
       commands, in a manner similar to the way key bindings for
       ordinary commands are specified in the #command section.  The
       line-editing section consists of a list of keys and actions, one
       per line as in the example below.

EXAMPLE         top

       The following input file describes the set of default line-
       editing keys used by less:

            \t           forw-complete
            \17          back-complete
            \e\t         back-complete
            ^L           expand
            ^V           literal
            ^A           literal
            \el          right
            \kr          right
            \eh          left
            \kl          left
            \eb          word-left
            \e\kl        word-left
            \ew          word-right
            \e\kr        word-right
            \ei          insert
            \ex          delete
            \kx          delete
            \eX          word-delete
            \ekx         word-delete
            \e\b         word-backspace
            \e0          home
            \kh          home
            \e$          end
            \ke          end
            \ek          up
            \ku          up
            \ej          down
            ^G           abort


       The environment variable section begins with the line


       Following this line is a list of environment variable
       assignments.  Each line consists of an environment variable name,
       an equals sign (=) and the value to be assigned to the
       environment variable.  White space before and after the equals
       sign is ignored.  Variables assigned in this way are visible only
       to less.  If a variable is specified in the system environment
       and also in a lesskey file, the value in the lesskey file takes

       If the variable name is followed by += rather than =, the string
       is appended to the variable's existing value.  This currently
       works only if any += lines immediately follow the same variable's
       original definition (with an = line), without any intervening
       definitions of other variables.  It can append only to a variable
       defined earlier in the file; it cannot append to a variable in
       the system environment.  The string is appended literally,
       without any extra whitespace added, so if whitespace is desired,
       it should be appended to the end of the preceding line.  (It
       cannot be added to the beginning of the += string because space
       after the equals sign is ignored, as noted above.)


       If a line begins with #version followed by a relational operator
       and a version number, the remainder of the line is parsed if and
       only if the running version of less (or lesskey) matches the
       operator.  This can be helpful if a lesskey file is used by
       different versions of less.

       For example, suppose that a new command named 'sideways-search'
       is added in less version 777.  Then the following line would
       assign the command to the Q key, but only in versions of less
       which support it. The line would be ignored by versions earlier
       than 777.

            #version >= 777  Q sideways-search

       These six operators are supported:
             >    Greater than
             <    Less than
             >=   Greater than or equal to
             <=   Less than or equal to
             =    Equal to
             !=   Not equal to

       The #version feature is not supported in less and lesskey before
       version 594.  In those older versions, all #version lines are

EXAMPLE         top

       The following input file sets the -i and -S options when is run
       and, on version 595 and higher, adds a --color option.

            ## (Note that there must be a space at the end of the next line,
            ##  to separate the --color option from the -S option.)
            LESS = -i -S
            #version >= 595  LESS += --color=Hkc

SEE ALSO         top


WARNINGS         top

       On MS-DOS and OS/2 systems, certain keys send a sequence of
       characters which start with a NUL character (0).  This NUL
       character should be represented as \340 in a lesskey file.

COPYRIGHT         top

       Copyright (C) 1984-2023  Mark Nudelman

       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.

       less is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       General Public License for more details.

AUTHOR         top

       Mark Nudelman
       Report bugs at https://github.com/gwsw/less/issues.

COLOPHON         top

       This page is part of the less (A file pager) project.
       Information about the project can be found at 
       ⟨http://www.greenwoodsoftware.com/less/⟩.  If you have a bug
       report for this manual page, see
       ⟨http://www.greenwoodsoftware.com/less/faq.html#bugs⟩.  This page
       was obtained from the tarball less-643.tar.gz fetched from
       ⟨http://www.greenwoodsoftware.com/less/download.html⟩ on
       2023-12-22.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to

                        Version 643: 20 Jul 2023              LESSKEY(1)

Pages that refer to this page: less(1)