readline: Readline Init File Syntax
1.3.1 Readline Init File Syntax
-------------------------------
There are only a few basic constructs allowed in the Readline init file.
Blank lines are ignored. Lines beginning with a '#' are comments.
Lines beginning with a '$' indicate conditional constructs (
Conditional Init Constructs). Other lines denote variable settings
and key bindings.
Variable Settings
You can modify the run-time behavior of Readline by altering the
values of variables in Readline using the 'set' command within the
init file. The syntax is simple:
set VARIABLE VALUE
Here, for example, is how to change from the default Emacs-like key
binding to use 'vi' line editing commands:
set editing-mode vi
Variable names and values, where appropriate, are recognized
without regard to case. Unrecognized variable names are ignored.
Boolean variables (those that can be set to on or off) are set to
on if the value is null or empty, ON (case-insensitive), or 1. Any
other value results in the variable being set to off.
A great deal of run-time behavior is changeable with the following
variables.
'bell-style'
Controls what happens when Readline wants to ring the terminal
bell. If set to 'none', Readline never rings the bell. If
set to 'visible', Readline uses a visible bell if one is
available. If set to 'audible' (the default), Readline
attempts to ring the terminal's bell.
'bind-tty-special-chars'
If set to 'on' (the default), Readline attempts to bind the
control characters treated specially by the kernel's terminal
driver to their Readline equivalents.
'blink-matching-paren'
If set to 'on', Readline attempts to briefly move the cursor
to an opening parenthesis when a closing parenthesis is
inserted. The default is 'off'.
'colored-completion-prefix'
If set to 'on', when listing completions, Readline displays
the common prefix of the set of possible completions using a
different color. The color definitions are taken from the
value of the 'LS_COLORS' environment variable. The default is
'off'.
'colored-stats'
If set to 'on', Readline displays possible completions using
different colors to indicate their file type. The color
definitions are taken from the value of the 'LS_COLORS'
environment variable. The default is 'off'.
'comment-begin'
The string to insert at the beginning of the line when the
'insert-comment' command is executed. The default value is
'"#"'.
'completion-display-width'
The number of screen columns used to display possible matches
when performing completion. The value is ignored if it is
less than 0 or greater than the terminal screen width. A
value of 0 will cause matches to be displayed one per line.
The default value is -1.
'completion-ignore-case'
If set to 'on', Readline performs filename matching and
completion in a case-insensitive fashion. The default value
is 'off'.
'completion-map-case'
If set to 'on', and COMPLETION-IGNORE-CASE is enabled,
Readline treats hyphens ('-') and underscores ('_') as
equivalent when performing case-insensitive filename matching
and completion.
'completion-prefix-display-length'
The length in characters of the common prefix of a list of
possible completions that is displayed without modification.
When set to a value greater than zero, common prefixes longer
than this value are replaced with an ellipsis when displaying
possible completions.
'completion-query-items'
The number of possible completions that determines when the
user is asked whether the list of possibilities should be
displayed. If the number of possible completions is greater
than this value, Readline will ask the user whether or not he
wishes to view them; otherwise, they are simply listed. This
variable must be set to an integer value greater than or equal
to 0. A negative value means Readline should never ask. The
default limit is '100'.
'convert-meta'
If set to 'on', Readline will convert characters with the
eighth bit set to an ASCII key sequence by stripping the
eighth bit and prefixing an <ESC> character, converting them
to a meta-prefixed key sequence. The default value is 'on',
but will be set to 'off' if the locale is one that contains
eight-bit characters.
'disable-completion'
If set to 'On', Readline will inhibit word completion.
Completion characters will be inserted into the line as if
they had been mapped to 'self-insert'. The default is 'off'.
'echo-control-characters'
When set to 'on', on operating systems that indicate they
support it, readline echoes a character corresponding to a
signal generated from the keyboard. The default is 'on'.
'editing-mode'
The 'editing-mode' variable controls which default set of key
bindings is used. By default, Readline starts up in Emacs
editing mode, where the keystrokes are most similar to Emacs.
This variable can be set to either 'emacs' or 'vi'.
'emacs-mode-string'
This string is displayed immediately before the last line of
the primary prompt when emacs editing mode is active. The
value is expanded like a key binding, so the standard set of
meta- and control prefixes and backslash escape sequences is
available. Use the '\1' and '\2' escapes to begin and end
sequences of non-printing characters, which can be used to
embed a terminal control sequence into the mode string. The
default is '@'.
'enable-bracketed-paste'
When set to 'On', Readline will configure the terminal in a
way that will enable it to insert each paste into the editing
buffer as a single string of characters, instead of treating
each character as if it had been read from the keyboard. This
can prevent pasted characters from being interpreted as
editing commands. The default is 'off'.
'enable-keypad'
When set to 'on', Readline will try to enable the application
keypad when it is called. Some systems need this to enable
the arrow keys. The default is 'off'.
'enable-meta-key'
When set to 'on', Readline will try to enable any meta
modifier key the terminal claims to support when it is called.
On many terminals, the meta key is used to send eight-bit
characters. The default is 'on'.
'expand-tilde'
If set to 'on', tilde expansion is performed when Readline
attempts word completion. The default is 'off'.
'history-preserve-point'
If set to 'on', the history code attempts to place the point
(the current cursor position) at the same location on each
history line retrieved with 'previous-history' or
'next-history'. The default is 'off'.
'history-size'
Set the maximum number of history entries saved in the history
list. If set to zero, any existing history entries are
deleted and no new entries are saved. If set to a value less
than zero, the number of history entries is not limited. By
default, the number of history entries is not limited. If an
attempt is made to set HISTORY-SIZE to a non-numeric value,
the maximum number of history entries will be set to 500.
'horizontal-scroll-mode'
This variable can be set to either 'on' or 'off'. Setting it
to 'on' means that the text of the lines being edited will
scroll horizontally on a single screen line when they are
longer than the width of the screen, instead of wrapping onto
a new screen line. By default, this variable is set to 'off'.
'input-meta'
If set to 'on', Readline will enable eight-bit input (it will
not clear the eighth bit in the characters it reads),
regardless of what the terminal claims it can support. The
default value is 'off', but Readline will set it to 'on' if
the locale contains eight-bit characters. The name
'meta-flag' is a synonym for this variable.
'isearch-terminators'
The string of characters that should terminate an incremental
search without subsequently executing the character as a
command (Searching). If this variable has not been
given a value, the characters <ESC> and 'C-J' will terminate
an incremental search.
'keymap'
Sets Readline's idea of the current keymap for key binding
commands. Acceptable 'keymap' names are 'emacs',
'emacs-standard', 'emacs-meta', 'emacs-ctlx', 'vi', 'vi-move',
'vi-command', and 'vi-insert'. 'vi' is equivalent to
'vi-command' ('vi-move' is also a synonym); 'emacs' is
equivalent to 'emacs-standard'. The default value is 'emacs'.
The value of the 'editing-mode' variable also affects the
default keymap.
'keyseq-timeout'
Specifies the duration Readline will wait for a character when
reading an ambiguous key sequence (one that can form a
complete key sequence using the input read so far, or can take
additional input to complete a longer key sequence). If no
input is received within the timeout, Readline will use the
shorter but complete key sequence. Readline uses this value
to determine whether or not input is available on the current
input source ('rl_instream' by default). The value is
specified in milliseconds, so a value of 1000 means that
Readline will wait one second for additional input. If this
variable is set to a value less than or equal to zero, or to a
non-numeric value, Readline will wait until another key is
pressed to decide which key sequence to complete. The default
value is '500'.
'mark-directories'
If set to 'on', completed directory names have a slash
appended. The default is 'on'.
'mark-modified-lines'
This variable, when set to 'on', causes Readline to display an
asterisk ('*') at the start of history lines which have been
modified. This variable is 'off' by default.
'mark-symlinked-directories'
If set to 'on', completed names which are symbolic links to
directories have a slash appended (subject to the value of
'mark-directories'). The default is 'off'.
'match-hidden-files'
This variable, when set to 'on', causes Readline to match
files whose names begin with a '.' (hidden files) when
performing filename completion. If set to 'off', the leading
'.' must be supplied by the user in the filename to be
completed. This variable is 'on' by default.
'menu-complete-display-prefix'
If set to 'on', menu completion displays the common prefix of
the list of possible completions (which may be empty) before
cycling through the list. The default is 'off'.
'output-meta'
If set to 'on', Readline will display characters with the
eighth bit set directly rather than as a meta-prefixed escape
sequence. The default is 'off', but Readline will set it to
'on' if the locale contains eight-bit characters.
'page-completions'
If set to 'on', Readline uses an internal 'more'-like pager to
display a screenful of possible completions at a time. This
variable is 'on' by default.
'print-completions-horizontally'
If set to 'on', Readline will display completions with matches
sorted horizontally in alphabetical order, rather than down
the screen. The default is 'off'.
'revert-all-at-newline'
If set to 'on', Readline will undo all changes to history
lines before returning when 'accept-line' is executed. By
default, history lines may be modified and retain individual
undo lists across calls to 'readline'. The default is 'off'.
'show-all-if-ambiguous'
This alters the default behavior of the completion functions.
If set to 'on', words which have more than one possible
completion cause the matches to be listed immediately instead
of ringing the bell. The default value is 'off'.
'show-all-if-unmodified'
This alters the default behavior of the completion functions
in a fashion similar to SHOW-ALL-IF-AMBIGUOUS. If set to
'on', words which have more than one possible completion
without any possible partial completion (the possible
completions don't share a common prefix) cause the matches to
be listed immediately instead of ringing the bell. The
default value is 'off'.
'show-mode-in-prompt'
If set to 'on', add a character to the beginning of the prompt
indicating the editing mode: emacs, vi command, or vi
insertion. The mode strings are user-settable. The default
value is 'off'.
'skip-completed-text'
If set to 'on', this alters the default completion behavior
when inserting a single match into the line. It's only active
when performing completion in the middle of a word. If
enabled, readline does not insert characters from the
completion that match characters after point in the word being
completed, so portions of the word following the cursor are
not duplicated. For instance, if this is enabled, attempting
completion when the cursor is after the 'e' in 'Makefile' will
result in 'Makefile' rather than 'Makefilefile', assuming
there is a single possible completion. The default value is
'off'.
'vi-cmd-mode-string'
This string is displayed immediately before the last line of
the primary prompt when vi editing mode is active and in
command mode. The value is expanded like a key binding, so
the standard set of meta- and control prefixes and backslash
escape sequences is available. Use the '\1' and '\2' escapes
to begin and end sequences of non-printing characters, which
can be used to embed a terminal control sequence into the mode
string. The default is '(cmd)'.
'vi-ins-mode-string'
This string is displayed immediately before the last line of
the primary prompt when vi editing mode is active and in
insertion mode. The value is expanded like a key binding, so
the standard set of meta- and control prefixes and backslash
escape sequences is available. Use the '\1' and '\2' escapes
to begin and end sequences of non-printing characters, which
can be used to embed a terminal control sequence into the mode
string. The default is '(ins)'.
'visible-stats'
If set to 'on', a character denoting a file's type is appended
to the filename when listing possible completions. The
default is 'off'.
Key Bindings
The syntax for controlling key bindings in the init file is simple.
First you need to find the name of the command that you want to
change. The following sections contain tables of the command name,
the default keybinding, if any, and a short description of what the
command does.
Once you know the name of the command, simply place on a line in
the init file the name of the key you wish to bind the command to,
a colon, and then the name of the command. There can be no space
between the key name and the colon - that will be interpreted as
part of the key name. The name of the key can be expressed in
different ways, depending on what you find most comfortable.
In addition to command names, readline allows keys to be bound to a
string that is inserted when the key is pressed (a MACRO).
KEYNAME: FUNCTION-NAME or MACRO
KEYNAME is the name of a key spelled out in English. For
example:
Control-u: universal-argument
Meta-Rubout: backward-kill-word
Control-o: "> output"
In the above example, 'C-u' is bound to the function
'universal-argument', 'M-DEL' is bound to the function
'backward-kill-word', and 'C-o' is bound to run the macro
expressed on the right hand side (that is, to insert the text
'> output' into the line).
A number of symbolic character names are recognized while
processing this key binding syntax: DEL, ESC, ESCAPE, LFD,
NEWLINE, RET, RETURN, RUBOUT, SPACE, SPC, and TAB.
"KEYSEQ": FUNCTION-NAME or MACRO
KEYSEQ differs from KEYNAME above in that strings denoting an
entire key sequence can be specified, by placing the key
sequence in double quotes. Some GNU Emacs style key escapes
can be used, as in the following example, but the special
character names are not recognized.
"\C-u": universal-argument
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
In the above example, 'C-u' is again bound to the function
'universal-argument' (just as it was in the first example),
''C-x' 'C-r'' is bound to the function 're-read-init-file',
and '<ESC> <[> <1> <1> <~>' is bound to insert the text
'Function Key 1'.
The following GNU Emacs style escape sequences are available when
specifying key sequences:
'\C-'
control prefix
'\M-'
meta prefix
'\e'
an escape character
'\\'
backslash
'\"'
<">, a double quotation mark
'\''
<'>, a single quote or apostrophe
In addition to the GNU Emacs style escape sequences, a second set
of backslash escapes is available:
'\a'
alert (bell)
'\b'
backspace
'\d'
delete
'\f'
form feed
'\n'
newline
'\r'
carriage return
'\t'
horizontal tab
'\v'
vertical tab
'\NNN'
the eight-bit character whose value is the octal value NNN
(one to three digits)
'\xHH'
the eight-bit character whose value is the hexadecimal value
HH (one or two hex digits)
When entering the text of a macro, single or double quotes must be
used to indicate a macro definition. Unquoted text is assumed to
be a function name. In the macro body, the backslash escapes
described above are expanded. Backslash will quote any other
character in the macro text, including '"' and '''. For example,
the following binding will make ''C-x' \' insert a single '\' into
the line:
"\C-x\\": "\\"
Info Catalog
readline: Readline Init File
readline: Conditional Init Constructs