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This document describes the end user interface of the GNU Readline Library, a utility which aids in the consistency of user interface across discrete programs which provide a command line interface. The Readline home page is http://www.gnu.org/software/readline/.
1. Command Line Editing GNU Readline User's Manual. A. GNU Free Documentation License License for copying this manual.
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This chapter describes the basic features of the GNU command line editing interface.
1.1 Introduction to Line Editing Notation used in this text. 1.2 Readline Interaction The minimum set of commands for editing a line. 1.3 Readline Init File Customizing Readline from a user's view. 1.4 Bindable Readline Commands A description of most of the Readline commands available for binding 1.5 Readline vi Mode A short description of how to make Readline behave like the vi editor.
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The following paragraphs describe the notation used to represent keystrokes.
The text C-k is read as `Control-K' and describes the character produced when the k key is pressed while the Control key is depressed.
The text M-k is read as `Meta-K' and describes the character produced when the Meta key (if you have one) is depressed, and the k key is pressed. The Meta key is labeled ALT on many keyboards. On keyboards with two keys labeled ALT (usually to either side of the space bar), the ALT on the left side is generally set to work as a Meta key. The ALT key on the right may also be configured to work as a Meta key or may be configured as some other modifier, such as a Compose key for typing accented characters.
If you do not have a Meta or ALT key, or another key working as a Meta key, the identical keystroke can be generated by typing ESC first, and then typing k. Either process is known as metafying the k key.
The text M-C-k is read as `Meta-Control-k' and describes the character produced by metafying C-k.
In addition, several keys have their own names. Specifically, DEL, ESC, LFD, SPC, RET, and TAB all stand for themselves when seen in this text, or in an init file (see section 1.3 Readline Init File). If your keyboard lacks a LFD key, typing C-j will produce the desired character. The RET key may be labeled Return or Enter on some keyboards.
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Often during an interactive session you type in a long line of text, only to notice that the first word on the line is misspelled. The Readline library gives you a set of commands for manipulating the text as you type it in, allowing you to just fix your typo, and not forcing you to retype the majority of the line. Using these editing commands, you move the cursor to the place that needs correction, and delete or insert the text of the corrections. Then, when you are satisfied with the line, you simply press RET. You do not have to be at the end of the line to press RET; the entire line is accepted regardless of the location of the cursor within the line.
1.2.1 Readline Bare Essentials The least you need to know about Readline. 1.2.2 Readline Movement Commands Moving about the input line. 1.2.3 Readline Killing Commands How to delete text, and how to get it back! 1.2.4 Readline Arguments Giving numeric arguments to commands. 1.2.5 Searching for Commands in the History Searching through previous lines.
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In order to enter characters into the line, simply type them. The typed character appears where the cursor was, and then the cursor moves one space to the right. If you mistype a character, you can use your erase character to back up and delete the mistyped character.
Sometimes you may mistype a character, and not notice the error until you have typed several other characters. In that case, you can type C-b to move the cursor to the left, and then correct your mistake. Afterwards, you can move the cursor to the right with C-f.
When you add text in the middle of a line, you will notice that characters to the right of the cursor are `pushed over' to make room for the text that you have inserted. Likewise, when you delete text behind the cursor, characters to the right of the cursor are `pulled back' to fill in the blank space created by the removal of the text. A list of the bare essentials for editing the text of an input line follows.
(Depending on your configuration, the Backspace key be set to delete the character to the left of the cursor and the DEL key set to delete the character underneath the cursor, like C-d, rather than the character to the left of the cursor.)
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The above table describes the most basic keystrokes that you need in order to do editing of the input line. For your convenience, many other commands have been added in addition to C-b, C-f, C-d, and DEL. Here are some commands for moving more rapidly about the line.
Notice how C-f moves forward a character, while M-f moves forward a word. It is a loose convention that control keystrokes operate on characters while meta keystrokes operate on words.
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Killing text means to delete the text from the line, but to save it away for later use, usually by yanking (re-inserting) it back into the line. (`Cut' and `paste' are more recent jargon for `kill' and `yank'.)
If the description for a command says that it `kills' text, then you can be sure that you can get the text back in a different (or the same) place later.
When you use a kill command, the text is saved in a kill-ring. Any number of consecutive kills save all of the killed text together, so that when you yank it back, you get it all. The kill ring is not line specific; the text that you killed on a previously typed line is available to be yanked back later, when you are typing another line.
Here is the list of commands for killing text.
Here is how to yank the text back into the line. Yanking means to copy the most-recently-killed text from the kill buffer.
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You can pass numeric arguments to Readline commands. Sometimes the argument acts as a repeat count, other times it is the sign of the argument that is significant. If you pass a negative argument to a command which normally acts in a forward direction, that command will act in a backward direction. For example, to kill text back to the start of the line, you might type `M-- C-k'.
The general way to pass numeric arguments to a command is to type meta digits before the command. If the first `digit' typed is a minus sign (`-'), then the sign of the argument will be negative. Once you have typed one meta digit to get the argument started, you can type the remainder of the digits, and then the command. For example, to give the C-d command an argument of 10, you could type `M-1 0 C-d', which will delete the next ten characters on the input line.
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Readline provides commands for searching through the command history for lines containing a specified string. There are two search modes: incremental and non-incremental.
Incremental searches begin before the user has finished typing the
search string.
As each character of the search string is typed, Readline displays
the next entry from the history matching the string typed so far.
An incremental search requires only as many characters as needed to
find the desired history entry.
To search backward in the history for a particular string, type
C-r. Typing C-s searches forward through the history.
The characters present in the value of the isearch-terminators variable
are used to terminate an incremental search.
If that variable has not been assigned a value, the ESC and
C-J characters will terminate an incremental search.
C-g will abort an incremental search and restore the original line.
When the search is terminated, the history entry containing the
search string becomes the current line.
To find other matching entries in the history list, type C-r or C-s as appropriate. This will search backward or forward in the history for the next entry matching the search string typed so far. Any other key sequence bound to a Readline command will terminate the search and execute that command. For instance, a RET will terminate the search and accept the line, thereby executing the command from the history list. A movement command will terminate the search, make the last line found the current line, and begin editing.
Readline remembers the last incremental search string. If two C-rs are typed without any intervening characters defining a new search string, any remembered search string is used.
Non-incremental searches read the entire search string before starting to search for matching history lines. The search string may be typed by the user or be part of the contents of the current line.
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Although the Readline library comes with a set of Emacs-like
keybindings installed by default, it is possible to use a different set
of keybindings.
Any user can customize programs that use Readline by putting
commands in an inputrc file, conventionally in his home directory.
The name of this
file is taken from the value of the environment variable INPUTRC. If
that variable is unset, the default is `~/.inputrc'. If that
file does not exist or cannot be read, the ultimate default is
`/etc/inputrc'.
When a program which uses the Readline library starts up, the init file is read, and the key bindings are set.
In addition, the C-x C-r command re-reads this init file, thus
incorporating any changes that you might have made to it.
1.3.1 Readline Init File Syntax Syntax for the commands in the inputrc file.
1.3.2 Conditional Init Constructs Conditional key bindings in the inputrc file.
1.3.3 Sample Init File An example inputrc file.
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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 1.3.2 Conditional Init Constructs). Other lines denote variable settings and key bindings.
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
bind-tty-special-chars
blink-matching-paren
colored-completion-prefix
LS_COLORS
environment variable.
The default is `off'.
colored-stats
LS_COLORS
environment variable.
The default is `off'.
comment-begin
insert-comment command is executed. The default value
is "#".
completion-display-width
completion-ignore-case
completion-map-case
completion-prefix-display-length
completion-query-items
100.
convert-meta
disable-completion
self-insert. The default is `off'.
echo-control-characters
editing-mode
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
enable-bracketed-paste
enable-keypad
enable-meta-key
expand-tilde
history-preserve-point
previous-history
or next-history. The default is `off'.
history-size
horizontal-scroll-mode
input-meta
meta-flag is a synonym for this variable.
isearch-terminators
keymap
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
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
mark-modified-lines
mark-symlinked-directories
mark-directories).
The default is `off'.
match-hidden-files
menu-complete-display-prefix
output-meta
page-completions
more-like pager
to display a screenful of possible completions at a time.
This variable is `on' by default.
print-completions-horizontally
revert-all-at-newline
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
show-all-if-unmodified
show-mode-in-prompt
skip-completed-text
vi-cmd-mode-string
vi-ins-mode-string
visible-stats
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).
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.
"\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-
\M-
\e
\\
\"
\'
In addition to the GNU Emacs style escape sequences, a second set of backslash escapes is available:
\a
\b
\d
\f
\n
\r
\t
\v
\nnn
\xHH
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\\": "\\" |
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Readline implements a facility similar in spirit to the conditional compilation features of the C preprocessor which allows key bindings and variable settings to be performed as the result of tests. There are four parser directives used.
$if
$if construct allows bindings to be made based on the
editing mode, the terminal being used, or the application using
Readline. The text of the test extends to the end of the line;
no characters are required to isolate it.
mode
mode= form of the $if directive is used to test
whether Readline is in emacs or vi mode.
This may be used in conjunction
with the `set keymap' command, for instance, to set bindings in
the emacs-standard and emacs-ctlx keymaps only if
Readline is starting out in emacs mode.
term
term= form may be used to include terminal-specific
key bindings, perhaps to bind the key sequences output by the
terminal's function keys. The word on the right side of the
`=' is tested against both the full name of the terminal and
the portion of the terminal name before the first `-'. This
allows sun to match both sun and sun-cmd,
for instance.
application
$if Bash # Quote the current or previous word "\C-xq": "\eb\"\ef\"" $endif |
$endif
$if command.
$else
$if directive are executed if
the test fails.
$include
$include /etc/inputrc |
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Here is an example of an inputrc file. This illustrates key binding, variable assignment, and conditional syntax.
# This file controls the behaviour of line input editing for
# programs that use the GNU Readline library. Existing
# programs include FTP, Bash, and GDB.
#
# You can re-read the inputrc file with C-x C-r.
# Lines beginning with '#' are comments.
#
# First, include any system-wide bindings and variable
# assignments from /etc/Inputrc
$include /etc/Inputrc
#
# Set various bindings for emacs mode.
set editing-mode emacs
$if mode=emacs
Meta-Control-h: backward-kill-word Text after the function name is ignored
#
# Arrow keys in keypad mode
#
#"\M-OD": backward-char
#"\M-OC": forward-char
#"\M-OA": previous-history
#"\M-OB": next-history
#
# Arrow keys in ANSI mode
#
"\M-[D": backward-char
"\M-[C": forward-char
"\M-[A": previous-history
"\M-[B": next-history
#
# Arrow keys in 8 bit keypad mode
#
#"\M-\C-OD": backward-char
#"\M-\C-OC": forward-char
#"\M-\C-OA": previous-history
#"\M-\C-OB": next-history
#
# Arrow keys in 8 bit ANSI mode
#
#"\M-\C-[D": backward-char
#"\M-\C-[C": forward-char
#"\M-\C-[A": previous-history
#"\M-\C-[B": next-history
C-q: quoted-insert
$endif
# An old-style binding. This happens to be the default.
TAB: complete
# Macros that are convenient for shell interaction
$if Bash
# edit the path
"\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f"
# prepare to type a quoted word --
# insert open and close double quotes
# and move to just after the open quote
"\C-x\"": "\"\"\C-b"
# insert a backslash (testing backslash escapes
# in sequences and macros)
"\C-x\\": "\\"
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
# Add a binding to refresh the line, which is unbound
"\C-xr": redraw-current-line
# Edit variable on current line.
"\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y="
$endif
# use a visible bell if one is available
set bell-style visible
# don't strip characters to 7 bits when reading
set input-meta on
# allow iso-latin1 characters to be inserted rather
# than converted to prefix-meta sequences
set convert-meta off
# display characters with the eighth bit set directly
# rather than as meta-prefixed characters
set output-meta on
# if there are more than 150 possible completions for
# a word, ask the user if he wants to see all of them
set completion-query-items 150
# For FTP
$if Ftp
"\C-xg": "get \M-?"
"\C-xt": "put \M-?"
"\M-.": yank-last-arg
$endif
|
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1.4.1 Commands For Moving Moving about the line. 1.4.2 Commands For Manipulating The History Getting at previous lines. 1.4.3 Commands For Changing Text Commands for changing text. 1.4.4 Killing And Yanking Commands for killing and yanking. 1.4.5 Specifying Numeric Arguments Specifying numeric arguments, repeat counts. 1.4.6 Letting Readline Type For You Getting Readline to do the typing for you. 1.4.7 Keyboard Macros Saving and re-executing typed characters 1.4.8 Some Miscellaneous Commands Other miscellaneous commands.
This section describes Readline commands that may be bound to key sequences. Command names without an accompanying key sequence are unbound by default.
In the following descriptions, point refers to the current cursor
position, and mark refers to a cursor position saved by the
set-mark command.
The text between the point and mark is referred to as the region.
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beginning-of-line (C-a)
end-of-line (C-e)
forward-char (C-f)
backward-char (C-b)
forward-word (M-f)
backward-word (M-b)
clear-screen (C-l)
redraw-current-line ()
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accept-line (Newline or Return)
add_history().
If this line is a modified history line, the history line is restored
to its original state.
previous-history (C-p)
next-history (C-n)
beginning-of-history (M-<)
end-of-history (M->)
reverse-search-history (C-r)
forward-search-history (C-s)
non-incremental-reverse-search-history (M-p)
non-incremental-forward-search-history (M-n)
history-search-forward ()
history-search-backward ()
history-substr-search-forward ()
history-substr-search-backward ()
yank-nth-arg (M-C-y)
yank-last-arg (M-. or M-_)
yank-nth-arg.
Successive calls to yank-last-arg move back through the history
list, inserting the last word (or the word specified by the argument to
the first call) of each line in turn.
Any numeric argument supplied to these successive calls determines
the direction to move through the history. A negative argument switches
the direction through the history (back or forward).
The history expansion facilities are used to extract the last argument,
as if the `!$' history expansion had been specified.
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end-of-file (usually C-d)
stty. If this character is read when there are no characters
on the line, and point is at the beginning of the line, Readline
interprets it as the end of input and returns EOF.
delete-char (C-d)
backward-delete-char (Rubout)
forward-backward-delete-char ()
quoted-insert (C-q or C-v)
tab-insert (M-TAB)
self-insert (a, b, A, 1, !, ...)
bracketed-paste-begin ()
self-insert) instead of
executing any editing commands.
transpose-chars (C-t)
transpose-words (M-t)
upcase-word (M-u)
downcase-word (M-l)
capitalize-word (M-c)
overwrite-mode ()
emacs mode; vi mode does overwrite differently.
Each call to readline() starts in insert mode.
In overwrite mode, characters bound to self-insert replace
the text at point rather than pushing the text to the right.
Characters bound to backward-delete-char replace the character
before point with a space.
By default, this command is unbound.
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kill-line (C-k)
backward-kill-line (C-x Rubout)
unix-line-discard (C-u)
kill-whole-line ()
kill-word (M-d)
forward-word.
backward-kill-word (M-DEL)
backward-word.
unix-word-rubout (C-w)
unix-filename-rubout ()
delete-horizontal-space ()
kill-region ()
copy-region-as-kill ()
copy-backward-word ()
backward-word.
By default, this command is unbound.
copy-forward-word ()
forward-word.
By default, this command is unbound.
yank (C-y)
yank-pop (M-y)
yank or yank-pop.
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digit-argument (M-0, M-1, ... M--)
universal-argument ()
universal-argument
again ends the numeric argument, but is otherwise ignored.
As a special case, if this command is immediately followed by a
character that is neither a digit nor minus sign, the argument count
for the next command is multiplied by four.
The argument count is initially one, so executing this function the
first time makes the argument count four, a second time makes the
argument count sixteen, and so on.
By default, this is not bound to a key.
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complete (TAB)
possible-completions (M-?)
completion-display-width, the value of
the environment variable COLUMNS, or the screen width, in that order.
insert-completions (M-*)
possible-completions.
menu-complete ()
complete, but replaces the word to be completed
with a single match from the list of possible completions.
Repeated execution of menu-complete steps through the list
of possible completions, inserting each match in turn.
At the end of the list of completions, the bell is rung
(subject to the setting of bell-style)
and the original text is restored.
An argument of n moves n positions forward in the list
of matches; a negative argument may be used to move backward
through the list.
This command is intended to be bound to TAB, but is unbound
by default.
menu-complete-backward ()
menu-complete, but moves backward through the list
of possible completions, as if menu-complete had been given a
negative argument.
delete-char-or-list ()
delete-char).
If at the end of the line, behaves identically to
possible-completions.
This command is unbound by default.
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start-kbd-macro (C-x ()
end-kbd-macro (C-x ))
call-last-kbd-macro (C-x e)
print-last-kbd-macro ()
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re-read-init-file (C-x C-r)
abort (C-g)
bell-style).
do-uppercase-version (M-a, M-b, M-x, ...)
prefix-meta (ESC)
undo (C-_ or C-x C-u)
revert-line (M-r)
undo
command enough times to get back to the beginning.
tilde-expand (M-~)
set-mark (C-@)
exchange-point-and-mark (C-x C-x)
character-search (C-])
character-search-backward (M-C-])
skip-csi-sequence ()
insert-comment (M-#)
comment-begin
variable is inserted at the beginning of the current line.
If a numeric argument is supplied, this command acts as a toggle: if
the characters at the beginning of the line do not match the value
of comment-begin, the value is inserted, otherwise
the characters in comment-begin are deleted from the beginning of
the line.
In either case, the line is accepted as if a newline had been typed.
dump-functions ()
dump-variables ()
dump-macros ()
emacs-editing-mode (C-e)
vi command mode, this causes a switch to emacs
editing mode.
vi-editing-mode (M-C-j)
emacs editing mode, this causes a switch to vi
editing mode.
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While the Readline library does not have a full set of vi
editing functions, it does contain enough to allow simple editing
of the line. The Readline vi mode behaves as specified in
the POSIX standard.
In order to switch interactively between emacs and vi
editing modes, use the command M-C-j (bound to emacs-editing-mode
when in vi mode and to vi-editing-mode in emacs mode).
The Readline default is emacs mode.
When you enter a line in vi mode, you are already placed in
`insertion' mode, as if you had typed an `i'. Pressing ESC
switches you into `command' mode, where you can edit the text of the
line with the standard vi movement keys, move to previous
history lines with `k' and subsequent lines with `j', and
so forth.
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Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. http://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. |
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To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:
Copyright (C) year your name. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. |
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with...Texts." line with this:
with the Invariant Sections being list their titles, with
the Front-Cover Texts being list, and with the Back-Cover Texts
being list.
|
If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.
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1. Command Line Editing
A. GNU Free Documentation License
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