[4mLESSKEY[24m(1)                  General Commands Manual                 [4mLESSKEY[24m(1)

[1mNAME[0m
       lesskey - customize key bindings for less

[1mSYNOPSIS (deprecated)[0m
       [1mlesskey [22m[[1m-o [4m[22moutput[24m] [1m-- [4m[22minput[0m
       [1mlesskey [22m[[1m--output=[4m[22moutput[24m] [1m-- [4m[22minput[0m

       [1mlesskey -V[0m
       [1mlesskey --version[0m

[1mSCOPE[0m
       This document describes the format of the [1mlesskey [22msource file, which is
       used  by  [1mless  [22mversion 582 and later.  In previous versions of [1mless[22m, a
       separate program called [1mlesskey [22mwas used to compile the [1mlesskey  [22msource
       file  into  a  format  understood by [1mless[22m.  This compilation step is no
       longer required and the [1mlesskey [22mprogram is  therefore  deprecated,  al‐
       though the file format remains supported by [1mless [22mitself.

[1mDESCRIPTION[0m
       A  [1mlesskey  [22mfile  specifies a set of key bindings and environment vari‐
       ables to be used by subsequent invocations of [1mless[22m.

[1mFILE FORMAT[0m
       The input file consists of one or more [4msections[24m.  Each  section  starts
       with  a  line  that  identifies the type of section.  Possible sections
       are:

       #command
              Customizes command key bindings.

       #line-edit
              Customizes line‐editing key bindings.

       #env   Defines environment variables.

       Blank lines are ignored.  Any text that follows an unescaped hash  mark
       (#) in a line is ignored, except as noted below.

[1mCOMMAND SECTION[0m
       The command section begins with the line

       #command

       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:

            [4mstring[24m <whitespace> [4maction[24m <whitespace> [extra‐string] <newline>

       Whitespace is any sequence of one or  more  spaces  and/or  tabs.   The
       [4mstring[24m  is  the command key(s) which invoke the action.  The [4mstring[24m may
       be a single command key, or a sequence of up to 15 keys.  The [4maction[24m is
       the name of the less action, from the lists in the EXAMPLE sections be‐
       low.  The characters in the [4mstring[24m 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  one or two characters represents the char(s) produced
       when one of these keys is pressed:
            \kb    BACKSPACE (the BACKSPACE key; may be different than \b)
            \kB    ctrl‐BACKSPACE
            \kd    DOWN ARROW
            \kD    PAGE DOWN
            \ke    END
            \kE    ctrl‐END
            \kF    shift‐END
            \kh    HOME
            \kH    ctrl‐HOME
            \kI    shift‐HOME
            \ki    INSERT
            \kl    LEFT ARROW
            \kL    ctrl‐LEFT ARROW
            \kM    shift‐LEFT ARROW
            \kr    RIGHT ARROW
            \kR    ctrl‐RIGHT ARROW
            \kS    shift‐RIGHT ARROW
            \kt    BACKTAB
            \ku    UP ARROW
            \kU    PAGE UP
            \kx    DELETE
            \kX    ctrl‐DELETE
            \k1    F1
            \kp1   lower left key on the numeric keypad
            \kp2   lower center key on the numeric keypad
            \kp3   lower right key on the numeric keypad
            \kp4   center left key on the numeric keypad
            \kp5   center key on the numeric keypad
            \kp6   center right key on the numeric keypad
            \kp7   upper left key on the numeric keypad
            \kp8   upper center key on the numeric keypad
            \kp9   upper right key on the numeric keypad
            \kp0   0 on the numeric keypad
            \kp*   * on the numeric keypad
            \kp/   / on the numeric keypad
            \kp-   - on the numeric keypad
            \kp+   + on the numeric keypad
            \kp.   . on the numeric keypad
            \kp,   , on the numeric keypad
            \kpe   ENTER on the numeric keypad

       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 [1mless[22m, the action is performed, and then the extra
       string  is  parsed,  just as if it were typed in to [1mless[22m.  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.  It
       can also be used to execute  more  than  one  command  when  a  key  is
       pressed.   For  example,  if this line were in a lesskey file, pressing
       the "B" key would first set the "b" mark and then search for the string
       "next":

           B set-mark b/next\n

       The extra string has a special meaning for the "quit" action: when [1mless[0m
       quits, the ASCII value of the first character of the  extra  string  is
       used as its exit status.

[1mEXAMPLE[0m
       The following input file describes the set of default command keys used
       by  [1mless[22m.   Documentation  on each command can be found in the [1mless [22mman
       page, under the key sequence which invokes the command.

            #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
            \ku        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
            \eb        back-screen-force
            \ej        forw-newline
            \ek        back-newline
            F          forw-forever
            \eF        forw-until-hilite
            \ef        forw-bell-hilite
            R          repaint-flush
            r          repaint
            ^R         repaint
            ^L         repaint
            \eu        undo-hilite
            \eU        clear-search
            g          goto-line
            \kh        goto-line
            \kH        goto-line \e{
            \kI        goto-line \e{
            \ke        goto-end
            \kE        goto-end \e}
            \kF        goto-end \e}
            <          goto-line
            \e<        goto-line
            p          percent
            %          percent
            \e(        left-scroll
            \e)        right-scroll
            \e{        no-scroll
            \e}        end-scroll
            \kl        left-scroll
            \kr        right-scroll
            \kL        no-scroll
            \kM        no-scroll
            \kR        end-scroll
            \kS        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
            P          goto-pos
            \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
            ^O^N       osc8-forw-search
            ^On        osc8-forw-search
            ^O^P       osc8-back-search
            ^Op        osc8-back-search
            ^O^O       osc8-open
            ^Oo        osc8-open
            ^O^L       osc8-jump
            ^Ol        osc8-jump
            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
            \e[M       mouse
            \e[<       mouse6
            \kp1       goto-end
            \kp2       forw-line
            \kp3       forw-screen
            \kp4       left-scroll
            \kp6       right-scroll
            \kp7       goto-line
            \kp8       back-line
            \kp9       back-screen
            \kp0       noaction 0
            \kp*       noaction *
            \kp/       noaction /
            \kp-       noaction -
            \kp+       noaction +
            \kp.       noaction .
            \kp,       noaction ,
            H          help
            h          help
            \k1        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

[1mPRECEDENCE[0m
       Commands specified by [1mlesskey [22mtake precedence  over  the  default  com‐
       mands.   A  default  command key may be disabled by including it in the
       input file with the action "invalid".  Alternatively, a key may be  de‐
       fined to do nothing by using the action "noaction".  "noaction" is sim‐
       ilar  to  "invalid",  but [1mless [22mwill 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:

       #stop

       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.

[1mLINE EDITING SECTION[0m
       The line‐editing section begins with the line:

       #line-edit

       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.

[1mEXAMPLE[0m
       The following input file describes the set of default line‐editing keys
       used by [1mless[22m:

            #line-edit
            \t           forw-complete
            \17          back-complete
            \ekt         back-complete
            \e\t         back-complete
            ˆL           expand
            ˆV           literal
            ˆA           literal
            \el          right
            \kr          right
            \eh          left
            \kl          left
            \eb          word-left
            \e\kl        word-left
            \e\kL        word-left
            \ew          word-right
            \e\kr        word-right
            \e\kR        word-right
            \ei          insert
            \ki          insert
            \ex          delete
            \kx          delete
            \eX          word-delete
            \ekx         word-delete
            \kX          word-delete
            \e\b         word-backspace
            \kB          word-backspace
            \e0          home
            \kh          home
            \e$          end
            \ke          end
            \ek          up
            \ku          up
            \ej          down
            \kd          down
            ˆG           abort
            \kp1         end
            \kp2         down
            \kp4         left
            \kp6         right
            \kp7         home
            \kp8         up
            \kp0         noaction 0
            \kp*         noaction *
            \kp/         noaction /
            \kp-         noaction -
            \kp+         noaction +
            \kp.         noaction .
            \kp,         noaction ,
            \e[M         mouse
            \e[<         mouse6

[1mLESS ENVIRONMENT VARIABLES[0m
       The environment variable section begins with the line

       #env

       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 [1mless[22m.  If a variable is specified  in  the
       system environment and also in a lesskey file, the value in the lesskey
       file takes precedence.

       If the variable name is followed by += rather than =, the string is ap‐
       pended  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  vari‐
       ables.   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 white‐
       space  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.)

       In  the string after the = sign, a substring of the form ${NAME} is re‐
       placed with the value of the environment variable "NAME".  The value of
       the variable may come from either the system  environment,  an  earlier
       lesskey  file,  or  an  earlier definition in the current lesskey file.
       Simple  text  replacements  can  be  performed  by  using  the   syntax
       ${NAME/STRING/REPL}.   This  replaces  all instances of "STRING" in the
       named environment variable with the text "REPL".  STRING is matched us‐
       ing a simple text comparison; no metacharacters are supported.  An  in‐
       stance  of  slash  or right curly bracket in STRING or REPL must be es‐
       caped by preceding it with  [4mtwo[24m  backslashes.   If  REPL  is  an  empty
       string,  all  instances of STRING are removed.  A slash immediately be‐
       fore the right curly bracket may be omitted.  Multiple replacements may
       be performed by using  the  syntax  ${NAME/STRING1/REPL1/STRING2/REPL2}
       and so on.

[1mCONDITIONAL CONFIGURATION[0m
       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 [1mless [22m(or [1mlesskey[22m) matches the operator.  This can be
       helpful if a lesskey file is used by different versions of [1mless[22m.

       For  example,  suppose  that  a  new command named ’sideways-search’ is
       added in [1mless [22mversion 777.  Then the following line  would  assign  the
       command  to  the  Q key, but only in versions of [1mless [22mwhich 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 [1mless [22mand [1mlesskey  [22mbefore  ver‐
       sion 594.  In those older versions, all #version lines are ignored.

[1mEXAMPLE[0m
       The  following  input  file sets the -i and -S options when [1mless [22mis run
       and, on version 595 and higher, adds a --color option.

            #env
            ## (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

[1mSEE ALSO[0m
       [1mless[22m(1)

[1mWARNINGS[0m
       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.

[1mCOPYRIGHT[0m
       Copyright (C) 1984‐2026  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
       Report bugs at https://github.com/gwsw/less/issues.

less 701                          13 May 2026                       [4mLESSKEY[24m(1)
