LESSKEY(1)

NAME
lesskey - specify key bindings for less

SYNOPSIS
lesskey [-o output | --output=output] [input]
lesskey -V | --version

DESCRIPTION
lesskey is used to specify a set of key bindings to be used by 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:

string <whitespace> action [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 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
\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 indicates 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. 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, 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:

    #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
    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
    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
    !	shell
    +	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

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, and specifies the character set to be "latin1":

    #env
    LESS = -i
    LESSCHARSET = latin1

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 <markn@greenwoodsoftware.com>

Send bug reports or comments to the above address or to <bug-less@gnu.org>.

CAVEATS
It is not possible to specify special keys, such as uparrow, in a keyboard-independent manner. The only way to specify such keys is to specify the escape sequence which a particular keyboard sends when such a key is pressed.