8.3.1 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 (see section 8.3.2 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
set command within the init file.
The syntax is simple:
Here, for example, is how to
change from the default Emacs-like key binding to use
vi line editing commands:
Variable names and values, where appropriate, are recognized without regard
bind -V command lists the current Readline variable names
and values. See section 4.2 Bash Builtin Commands.
A great deal of run-time behavior is changeable with the following
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.
The string to insert at the beginning of the line when the
insert-comment command is executed. The default value
- If set to `on', Readline performs filename matching and completion
in a case-insensitive fashion.
The default value is `off'.
The number of possible completions that determines when the user is
asked whether he wants to see the list of possibilities. 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.
The default limit is
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'.
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'.
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'.
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'.
If set to `on', tilde expansion is performed when Readline
attempts word completion. The default is `off'.
If set to `on', the history code attempts to place point at the
same location on each history line retrived with
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'.
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'. The name
meta-flag is a
synonym for this variable.
The string of characters that should terminate an incremental search without
subsequently executing the character as a command (see section 8.2.5 Searching for Commands in the History).
If this variable has not been given a value, the characters ESC and
C-J will terminate an incremental search.
Sets Readline's idea of the current keymap for key binding commands.
keymap names are
vi is equivalent to
emacs-standard. The default value is
The value of the
editing-mode variable also affects the
- If set to `on', completed directory names have a slash
appended. The default is `on'.
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.
This variable, when set to `on', causes Readline to match files whose
names begin with a `.' (hidden files) when performing filename
completion, unless the leading `.' is
supplied by the user in the filename to be completed.
This variable is `on' by default.
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'.
- If set to `on', Readline will display completions with matches
sorted horizontally in alphabetical order, rather than down the screen.
The default is `off'.
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'.
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. The name of the key
can be expressed in different ways, depending on what you find most
In addition to command names, readline allows keys to be bound
to a string that is inserted when the key is pressed (a macro).
bind -p command displays Readline function names and
bindings in a format that can put directly into an initialization file.
See section 4.2 Bash Builtin Commands.
- keyname: function-name or macro
- keyname is the name of a key spelled out in English. For example:
Control-o: "> output"
In the above example, C-u is bound to the function
M-DEL is bound to the function
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:
- "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.
"\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
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:
- control prefix
- meta prefix
- an escape character
- ", 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:
- alert (bell)
- form feed
- carriage return
- horizontal tab
- vertical tab
- the eight-bit character whose value is the octal value nnn
(one to three digits)
- 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:
This document was generated
on May 3, 2002