Manual: lesskey
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 inā
vocations 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 and lines which start with a hash mark (#) are 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 secā
tion consists of lines of the form:
string action [extra-string]
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 acā
tion 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 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
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
\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
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
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 sufā
ficient commands before the #stop line to enable all necessary actions. For example, failure to proā
vide 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
\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
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 environā
ment 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 existā
ing 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 environā
ment. The string is appended literally, without any extra whitespace added, so if whitespace is deā
sired, 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 enā
vironment 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 compariā
son; 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 reā
placements 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 verā
sions, 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 characā
ter (0). This NUL character should be represented as \340 in a lesskey file.
COPYRIGHT
Copyright (C) 1984-2024 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 reā
distribution. 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 Liā
cense; 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.
Version 668: 06 Oct 2024 LESSKEY(1)