LESSKEY(1)

📦

version 704 · 9 versions

704 · fedora 43, fedora 44, freebsd 14.5 (latest)
692 · freebsd 15.1, nixos 26.05
661 · centos-stream 10
685 · alpine 3.23
702 · alpine 3.24
679 · alpine 3.22, fedora 43
691 · fedora 44
590 · centos-stream 9, debian bookworm, ubuntu jammy, ubuntu noble
668 · debian trixie, opensuse-leap 16.0, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 LESSKEY(1) 💖

okay bestie, so this is the manual for lesskey — the little program that customizes your key bindings for less. general commands manual energy, but make it cute. let's get into it ✨

🌸 NAME 🌸

lesskey — customize key bindings for less

🎀 SYNOPSIS (deprecated) 🎀

ngl the title of this section literally says deprecated, so keep that in mind, bestie:

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

lesskey -V
lesskey --version

🦋 SCOPE 🦋

okay so listen. this document is describing the format of the lesskey source file, and that format is what less version 582 and later uses. in previous versions of less, there was a whole separate program called lesskey that compiled the lesskey source file into a format less could understand.

that compilation step? gone. not a thing anymore. so the lesskey program itself is deprecated, but the file format is still supported by less itself. periodt. 💅

💜 DESCRIPTION 💜

a lesskey file specifies a set of key bindings and environment variables to be used by subsequent invocations of less. that's the whole vibe. 🫶

🧚 FILE FORMAT 🧚

the input file is made of one or more sections. each section starts with a line that identifies the type of section. here are the possible sections, bestie:

#command — customizes command key bindings. 👑
#line-edit — customizes line-editing key bindings. ✏️
#env — defines environment variables. 🌈

blank lines are ignored, no cap. and any text that follows an unescaped hash mark (#) in a line is ignored too — except as noted below. so # is giving comment energy but with a lil asterisk. 💀

⭐ 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. iconic shortcut behavior, honestly.

the command section consists of lines of the form:

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

whitespace here means 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
\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. so yeah, some of these characters are main characters and need their lil escape entrance. 💅

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. so your exit code is literally lowkey decided by your extra string. wild. 😭

🔥 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. so one is loud and one is silent, basically. 🙈

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.

⚠️ bestie, 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. like, genuinely. you'll be stuck in there. 😭

part 1 done, bestie — there's more coming, so don't go anywhere 🫶

✨ LINE EDITING SECTION ✨

okay bestie, this section kicks off with the line:

#line-edit

and what it does is set up brand new key bindings for the line editing commands — basically the same way you'd specify key bindings for regular commands in the #command section. The line-editing section is just a list of keys and actions, one per line, exactly like the example down below. 💅

🌸 EXAMPLE 🌸

here's an input file that describes the whole set of default line-editing keys that less uses. iconic, honestly:

#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 🦋

this section starts with the line

#env

and right after it comes a list of environment variable assignments. Every single line is: an environment variable name, an equals sign (=), and then the value you're assigning to that variable. White space before and after the equals sign gets ignored, no stress. The variables you assign this way are visible only to less. And here's the tea: if a variable is specified in the system environment and also in a lesskey file, the value in the lesskey file wins. 👑

if the variable name is followed by += instead of =, then the string gets appended to the variable's existing value. quick heads up though, this currently only works if any += lines immediately follow the same variable's original definition (the = line), with no other variable definitions sneaking in between. It can only append to a variable defined earlier in the file — it cannot append to a variable that lives in the system environment. And the string is appended literally, with no extra whitespace added, so if you want whitespace you gotta put it at the end of the preceding line. (You can't add it to the beginning of the += string because, as we just said, space after the equals sign is ignored. 😭)

in the string after the = sign, a substring shaped like ${NAME} gets replaced with the value of the environment variable "NAME". That value can come from the system environment, from an earlier lesskey file, or from an earlier definition in the current lesskey file — any of those. Simple text replacements can be done with the syntax ${NAME/STRING/REPL}, which swaps out all instances of "STRING" inside the named environment variable with the text "REPL". STRING is matched using a simple text comparison — no metacharacters supported, sorry bestie. An instance of a slash or a right curly bracket in STRING or REPL has to be escaped by putting two backslashes in front of it. If REPL is an empty string, all instances of STRING get yeeted. A slash right before the right curly bracket can be omitted. And you can do multiple replacements with ${NAME/STRING1/REPL1/STRING2/REPL2} and so on and so forth. ✨

🎀 CONDITIONAL CONFIGURATION 🎀

if a line starts with #version followed by a relational operator and a version number, then the rest of that line is parsed if and only if the running version of less (or lesskey) matches the operator. super handy when one lesskey file is being used by different versions of less. 🫶

for example, say a new command called 'sideways-search' gets added in less version 777. Then this line would assign the command to the Q key, but only in versions of less that support it. Versions earlier than 777 would just ignore the line entirely.

#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

⚠️ real talk: the #version feature is not supported in less and lesskey before version 594. In those older versions, all #version lines are ignored. periodt.

🌈 EXAMPLE 🌈

this input file sets the -i and -S options whenever less is run, and on version 595 and higher it also adds a --color option. so versatile of it:

#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 that start with a NUL character (0). That NUL character should be represented as \340 in a lesskey file. noted. 🙈

👑 COPYRIGHT 👑

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.

okay that's the whole thing bestie, we ate and left no crumbs 🍓 this was less version 704, dated 30 May 2026, and this page is LESSKEY(1) — go forth and bind your keys, you main character 💜

📦 where this page comes from

fedora 43: less 704-4.fc43
fedora 44: less 704-4.fc44
freebsd 14.5: base 14.5
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-13: a language model's rewrite of the original, under its terms