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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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LESSKEY(1) General Commands Manual LESSKEY(1)
lesskey - customize key bindings for less
lesskey [-o output] [--] [input]
lesskey [--output=output] [--] [input]
lesskey -V
lesskey --version
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.
A lesskey file specifies a set of key bindings and environment
variables to be used by subsequent invocations of less.
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.
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 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 ASCII value of the first character of
the extra string is used as its exit status.
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
J forw-line-force
K back-line-force
Y back-line-force
\ej forw-newline
\ek back-newline
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
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
\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
^O^N osc8-forw-search
^On osc8-forw-search
^O^P osc8-back-search
^Op osc8-back-search
^O^O osc8-open
& 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
\e[M mouse
\e[< mouse6
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
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.
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.
The following input file describes the set of default line-editing
keys used by less:
#line-edit
\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
\e[M mouse
\e[< mouse6
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.
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.
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
less(1)
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 (C) 1984-2025 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.
Mark Nudelman
Report bugs at ⟨https://github.com/gwsw/less/issues⟩.
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-679.tar.gz fetched from
⟨http://www.greenwoodsoftware.com/less/download.html⟩ on
2025-08-11. 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
[email protected]
Version 679: 28 May 2025 LESSKEY(1)
Pages that refer to this page: less(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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