lesskey(1) General Commands Manual lesskey(1)
NAME
lesskey - customize key bindings for less
SYNOPSIS (deprecated)
lesskey [-o output] -- input
lesskey [--output=output] -- input
lesskey -V
lesskey --version
SCOPE
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
A lesskey file specifies a set of key bindings and environment
variables to be used by subsequent invocations of less.
FILE FORMAT
The input file consists of one or more sections. 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.
COMMAND SECTION
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:
string <whitespace> action <whitespace> [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 lists in the EXAMPLE sections
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 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
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. 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 less
quits, the ASCII value of the first character of the extra string is
used as its exit status.
EXAMPLE
The following input file describes the set of default command keys used
by less. Documentation on each command can be found in the less man
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
PRECEDENCE
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:
#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.
LINE EDITING SECTION
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.
EXAMPLE
The following input file describes the set of default line-editing keys
used by less:
#line-edit
\t forw-complete
\17 back-complete
\ekt 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
\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
^G 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
LESS ENVIRONMENT VARIABLES
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 less. 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
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.)
In the string after the = sign, a substring of the form ${NAME} is
replaced 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
using a simple text comparison; no metacharacters are supported. An
instance of slash or right curly bracket in STRING or REPL must be
escaped by preceding it with two backslashes. If REPL is an empty
string, all instances of STRING are removed. A slash immediately
before the right curly bracket may be omitted. Multiple replacements
may be performed by using the syntax
${NAME/STRING1/REPL1/STRING2/REPL2} and so on.
CONDITIONAL CONFIGURATION
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 ignored.
EXAMPLE
The following input file sets the -i and -S options when less is 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
SEE ALSO
less(1)
WARNINGS
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
Copyright (C) 1984-2026 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 MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
AUTHOR
Mark Nudelman
Report bugs at <https://github.com/gwsw/less/issues>.
less 692 29 Jan 2026 lesskey(1)
less 692 - Generated Sat Feb 14 16:24:51 CST 2026