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.\"	$OpenBSD: lesskey.1,v 1.18 2021/12/09 21:09:51 jmc Exp $
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.\" Copyright (C) 2000-2012  Mark Nudelman
.\"
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.Dd $Mdocdate: December 9 2021 $
.Dt LESSKEY 1
.Os
.Sh NAME
.Nm lesskey
.Nd customize key bindings for less
.Sh SYNOPSIS
.Nm lesskey
.Oo Fl o Ar output
.Pf " | " Fl -output Ns = Ns Ar output Oc
.Op Ar input
.Nm lesskey
.Fl V | -version
.Sh DESCRIPTION
.Nm
is used to change the default key bindings of
.Xr less 1 .
The input file is a text file which describes the key bindings.
If the input file is
.Sq - ,
standard input is read.
If no input file is specified, a standard filename is used
as the name of the input file; by default
.Pa $HOME/.lesskey .
.\" on MS-DOS systems, $HOME/_lesskey is used;
.\" and on OS/2 systems $HOME/lesskey.ini is used,
.\" or $INIT/lesskey.ini if $HOME is undefined.
The output file is a binary file which is used by
.Xr less 1 .
If no output file is specified, and the environment variable
.Ev LESSKEY
is set, the value of
.Ev 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
.Pa $HOME/.less
is used.
.\" on MS-DOS systems, $HOME/_less is used;
.\" and on OS/2 systems, $HOME/less.ini is used,
.\" or $INIT/less.ini if $HOME is undefined.
If the output file already exists,
.Nm
will overwrite it.
.Pp
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
.Ev LESSKEY_SYSTEM
is set,
.Xr less 1
uses that as the name of the system-wide lesskey file.
Otherwise,
.Xr less 1
looks in a standard place for the system-wide lesskey file:
On
.Ox ,
the system-wide lesskey file is
.Pa /etc/sysless .
.Pp
The
.Fl V
or
.Fl -version
option causes
.Nm
to print its version number and immediately exit.
If
.Fl V
or
.Fl -version
is present, other options and arguments are ignored.
.Pp
The input file consists of one or more sections.
Each section starts with a line that identifies the type of section.
Possible sections are:
.Bl -tag -width "#line-edit" -offset indent
.It #command
Defines new command keys.
.It #line-edit
Defines new line-editing keys.
.It #env
Defines environment variables.
.El
.Pp
Blank lines and lines which start with a pound sign (#) are ignored,
except for the special section header lines.
.Sh COMMAND SECTION
The command section begins with the line
.Pp
.Dl #command
.Pp
If the command section is the first section in the file,
this line may be omitted.
.Pp
The command section consists of lines of the form:
.Bd -filled -offset indent
.Ar keys
.Ar action
.Op Ar extra
.Ed
.Pp
The three fields are separated by whitespace
consisting of one or more spaces and/or tabs.
.Pp
The
.Ar keys
string consists of at least one and at most 15 keys.
By typing it in
.Xr less 1 ,
the
.Ar action
is invoked.
The list of default key bindings given below
also serves as a list of supported actions.
.Pp
Each of the
.Ar keys
can be specified in these forms:
.Bl -bullet -offset indent
.It
a literal character
.It
a character prefixed by a caret to indicate a control key
.It
a backslash followed by one to three octal digits
to specify a key by its octal value
.It
a backslash followed by certain characters
to specify input characters as follows:
.Pp
.Bl -tag -width Ds -offset indent -compact
.It \eb
BACKSPACE
.It \ee
ESCAPE
.It \en
NEWLINE
.It \er
RETURN
.It \et
TAB
.It \eku
UP ARROW
.It \ekd
DOWN ARROW
.It \ekr
RIGHT ARROW
.It \ekl
LEFT ARROW
.It \ekU
PAGE UP
.It \ekD
PAGE DOWN
.It \ekh
HOME
.It \eke
END
.It \ekx
DELETE
.El
.It
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.
.El
.Pp
An action may be followed by an
.Ar extra
string.
It is parsed, just as if it were typed into
.Xr less 1 ,
after performing the
.Ar action .
This feature can be used in certain cases to extend
the functionality of a command.
For example, see the
.Sq {
and
.Sq :t
keys in the list of default bindings below.
.Pp
The
.Ar extra
string has a special meaning for the
.Qq quit
action:
when
.Xr less 1
quits,
first character of the
.Ar extra
string is used as its exit status.
.Pp
The following input file describes the set of
default command keys used by
.Xr less 1 :
.Bd -literal -offset indent
#command
\er	forw-line
\en	forw-line
e	forw-line
j	forw-line
\ekd	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
\e40	forw-screen
f	forw-screen
^F	forw-screen
^V	forw-screen
\ekD	forw-screen
b	back-screen
^B	back-screen
\eev	back-screen
\ekU	back-screen
z	forw-window
w	back-window
\ee\e40	forw-screen-force
F	forw-forever
\eeF	forw-until-hilite
R	repaint-flush
r	repaint
^R	repaint
^L	repaint
\eeu	undo-hilite
g	goto-line
\ekh	goto-line
<	goto-line
\ee<	goto-line
p	percent
%	percent
\ee[	left-scroll
\ee]	right-scroll
\ee(	left-scroll
\ee)	right-scroll
{	forw-bracket {}
}	back-bracket {}
(	forw-bracket ()
)	back-bracket ()
[	forw-bracket []
]	back-bracket []
\ee^F	forw-bracket
\ee^B	back-bracket
G	goto-end
\ee>	goto-end
>	goto-end
\eke	goto-end
=	status
^G	status
:f	status
/	forw-search
?	back-search
\ee/	forw-search *
\ee?	back-search *
n	repeat-search
\een	repeat-search-all
N	reverse-search
\eeN	reverse-search-all
&	filter
m	set-mark
\(aq	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
.Ed
.Sh PRECEDENCE
Commands specified by
.Nm
take precedence over the default commands.
A default command key may be disabled by including it in the
input file with the action
.Qq invalid .
Alternatively, a key may be defined
to do nothing by using the action
.Qq noaction .
.Qq noaction
is similar to
.Qq invalid ,
but less will give an error beep for an
.Qq invalid
command, but not for a
.Qq noaction
command.
In addition, ALL default commands may be disabled by
adding this control line to the input file:
.Pp
.Dl #stop
.Pp
This will cause all default commands to be ignored.
The #stop line should be the last line in that section of the file.
.Pp
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
.Qq quit
command can lead to frustration.
.Sh LINE EDITING SECTION
The line-editing section begins with the line:
.Pp
.Dl #line-edit
.Pp
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.
.Pp
The following input file describes the set of
default line-editing keys used by less:
.Bd -literal -offset indent
#line-edit
\et	forw-complete
\e17	back-complete
\ee\et	back-complete
^L	expand
^V	literal
^A	literal
\eel	right
\ekr	right
\eeh	left
\ekl	left
\eeb	word-left
\ee\ekl	word-left
\eew	word-right
\ee\ekr	word-right
\eei	insert
\eex	delete
\ekx	delete
\eeX	word-delete
\eekx	word-delete
\ee\eb	word-backspace
\ee0	home
\ekh	home
\ee$	end
\eke	end
\eek	up
\eku	up
\eej	down
^G	abort
.Ed
.Sh ENVIRONMENT SECTION
The environment variable section begins with the line
.Pp
.Dl #env
.Pp
Following this line is a list of environment variable assignments.
Each line consists of an environment variable name, an equals sign
.Pq Sq =
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.
.Pp
The following input file sets the -i option whenever less is run:
.Bd -literal -offset indent
#env
LESS = -i
.Ed
.Sh ENVIRONMENT
.Bl -tag -width LESSKEY_SYSTEM -compact
.It Ev LESSKEY
Name of the default
.Nm
file.
.It Ev LESSKEY_SYSTEM
Name of the default system-wide
.Nm
file.
.El
.Sh FILES
.Bl -tag -width "$HOME/.lesskey" -compact
.It $HOME/.less
Default
.Nm
file.
.It $HOME/.lesskey
Default
.Nm
input file.
.It /etc/sysless
Default system-wide
.Nm
file.
.El
.Sh SEE ALSO
.Xr less 1
.Sh AUTHORS
.An Mark Nudelman