LESSKEY(1) | General Commands Manual | LESSKEY(1)

# NAME

`lesskey` — customize key bindings for less

# SYNOPSIS

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

`lesskey` | `-V` | `--version`

# DESCRIPTION

`lesskey` is used to change the default key bindings of less(1). The input file is a text file which describes the key bindings. If the input file is ‘-’, standard input is read. If no input file is specified, a standard filename is used as the name of the input file; by default $HOME/.lesskey. The output file is a binary file which is used by less(1). If no output file is specified, and the environment variable `LESSKEY` is set, the value of `LESSKEY` is used as the name of the output file. Otherwise, a standard filename is used as the name of the output file; by default $HOME/.less is used. If the output file already exists, `lesskey` will overwrite it.

A system-wide lesskey file may also be set up to provide key bindings. If a key is defined in both a local lesskey file and in the system-wide file, key bindings in the local file take precedence over those in the system-wide file. If the environment variable `LESSKEY_SYSTEM` is set, less(1) uses that as the name of the system-wide lesskey file. Otherwise, less(1) looks in a standard place for the system-wide lesskey file: On OpenBSD, the system-wide lesskey file is /etc/sysless.

The `-V` or `--version` option causes `lesskey` to print its version number and immediately exit. If `-V` or `--version` is present, other options and arguments are ignored.

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
  Defines new command keys.
#line-edit
  Defines new line-editing keys.
#env
  Defines environment variables.

Blank lines and lines which start with a pound sign (#) are ignored, except for the special section header lines.

# 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:

keys action [extra]

The three fields are separated by whitespace consisting of one or more spaces and/or tabs.

The keys string consists of at least one and at most 15 keys. By typing it in less(1), the action is invoked. The list of default key bindings given below also serves as a list of supported actions.

Each of the keys can be specified in these forms:

- a literal character
- a character prefixed by a caret to indicate a control key
- a backslash followed by one to three octal digits to specify a key by its octal value
- a backslash followed by certain characters to specify input characters as follows:

  \b
    BACKSPACE
  \e
    ESCAPE
  \n
    NEWLINE
  \r
    RETURN
  \t
    TAB
  \ku
    UP ARROW
  \kd
    DOWN ARROW
  \kr
    RIGHT ARROW
  \kl
    LEFT ARROW
  \kU
    PAGE UP
  \kD
    PAGE DOWN
  \kh
    HOME
  \ke
    END
  \kx
    DELETE
- a backslash followed by any other character to indicate that character is to be taken literally. Characters which must be preceded by backslash include caret, space, tab, and the backslash itself.

An action may be followed by an extra string. It is parsed, just as if it were typed into less(1), after performing the action. This feature can be used in certain cases to extend the functionality of a command. For example, see the ‘{’ and ‘:t’ keys in the list of default bindings below.

The extra string has a special meaning for the "quit" action: when less(1) quits, 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(1):

    #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
    g	goto-line
    \kh	goto-line
    <	goto-line
    \e<	goto-line
    p	percent
    %	percent
    \e[	left-scroll
    \e]	right-scroll
    \e(	left-scroll
    \e)	right-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
    =	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
    '	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
    _	display-option
    |	pipe
    v	visual
    +	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 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.

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

# ENVIRONMENT SECTION

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. Whitespace before and after the equals sign is ignored. Variables assigned in this way are visible only to less. If environment variables are defined in more than one place, variables defined in a local lesskey file take precedence over variables defined in the system environment, which take precedence over variables defined in the system-wide lesskey file. Although the lesskey file can be used to override variables set in the environment, the main purpose of assigning variables in the lesskey file is simply to have all less configuration information stored in one file.

The following input file sets the -i option whenever less is run:

    #env
    LESS = -i

# ENVIRONMENT

`LESSKEY`
  Name of the default `lesskey` file.
`LESSKEY_SYSTEM`
  Name of the default system-wide `lesskey` file.

# FILES

$HOME/.less
  Default `lesskey` file.
$HOME/.lesskey
  Default `lesskey` input file.
/etc/sysless
  Default system-wide `lesskey` file.

# SEE ALSO

less(1)

# AUTHORS

Mark Nudelman

December 9, 2021 | Debian