Man Page for READLINE
readline - get a line from a user with editing
#include <readline.h> #include <history.h> typedef int Function (); char *readline (prompt) char *prompt; int rl_add_defun (name, function, key) char *name; Function *function; int key; int rl_bind_key (key, function) int key; Function *function; int rl_unbind_key (key) int key; int rl_bind_key_in_map (key, function, keymap) int key; Function *function; Keymap keymap; int rl_unbind_key_in_map (key, keymap) int key; Keymap keymap; int rl_macro_bind (keyseq, macro, keymap) char *keyseq, *macro; Keymap keymap; int rl_variable_bind (variable, value) char *variable, *value; int rl_parse_and_bind (line) char *line; int rl_translate_keyseq (keyseq, array, len) char *keyseq, *array; int *len; Function *rl_named_function (command) char *command; Function *rl_function_of_keyseq (keyseq, keymap, type) char *keyseq; Keymap keymap; int *type; char **rl_invoking_keyseqs (function) Function *function; char **rl_invoking_keyseqs_in_map (function, keymap) Function *function; Keymap keymap; void rl_function_dumper (readable) int readable; char **rl_funmap_names ()
Readline is Copyright (C) 1989, 1991 by the Free Software Foundation, Inc.
readline will read a line from the terminal and return it, using prompt as a prompt. If prompt is null, no prompt is issued. The line returned is allocated with malloc(3), so the caller must free it when finished. The line returned has the final newline removed, so only the text of the line remains. readline offers editing capabilities while the user is entering the line. By default, the line editing commands are similar to those of emacs. A vi-style line editing interface is also available. In the following descriptions, keymap can be one of emacs_keymap, emacs_meta_keymap, emacs_ctlx_keymap, vi_insertion_keymap, or vi_movement_keymap. rl_add_defun makes name appear as a bindable readline com- mand, and makes function be the function called when that command is invoked. If key is not -1, it is bound to func- tion in the current keymap. rl_bind_key causes key to invoke function. The binding is made in the current keymap. rl_unbind_key removes the binding for key in the current keymap. rl_bind_key_in_map makes the key entry in keymap invoke function. rl_unbind_key_in_map removes the binding for key in keymap keymap. rl_macro_bind makes keyseq insert the string macro. The binding is performed in keymap. rl_variable_bind sets the value of the readline variable variable to value. rl_parse_and_bind takes as an argument a line of the same form as the readline startup file (see INITIALIZATION FILE below) and executes the commands therein. rl_translate_keyseq converts keyseq into a new string, stor- ing the result in array. This translates control and meta prefixes and the readline character escape sequences (see Key Bindings below). The length of the translated sequence is returned in *len. rl_named_function returns the function that is executed when the readline command command is invoked. rl_function_of_keyseq returns the function that is executed when keyseq is read and keymap is the current keymap. type is set to indicate whether the return value corresponds to a function, macro, or auxiliary keymap. rl_invoking_keyseqs returns all of the key sequences in the current keymap that invoke function. rl_invoking_keyseqs_in_map returns all of the key sequences in keymap that invoke function. rl_function_dumper prints all of the readline functions and their bindings to the readline output stream. If readable is non-zero, the output is formattted so that it can be read back in to restore the bindings. rl_funmap_names returns an array of all known readline bind- able function names. The array is sorted.
readline returns the text of the line read. A blank line returns the empty string. If EOF is encountered while read- ing a line, and the line is empty, NULL is returned. If an EOF is read with a non-empty line, it is treated as a new- line. Unless otherwise stated, the other functions return 0 on success and non-zero on failure.
An emacs-style notation is used to denote keystrokes. Con- trol keys are denoted by C-key, e.g., C-n means Control-N. Similarly, meta keys are denoted by M-key, so M-x means Meta-X. (On keyboards without a meta key, M-x means ESC x, i.e., press the Escape key then the x key. This makes ESC the meta prefix. The combination M-C-x means ESC-Control-x, or press the Escape key then hold the Control key while pressing the x key.) Readline commands may be given numeric arguments, which nor- mally act as a repeat count. Sometimes, however, it is the sign of the argument that is significant. Passing a nega- tive argument to a command that acts in the forward direc- tion (e.g., kill-line) causes that command to act in a back- ward direction. Commands whose behavior with arguments deviates from this are noted. When a command is described as killing text, the text deleted is saved for possible future retrieval (yanking). The killed text is saved in a kill-ring. Consecutive kills cause the text to be accumulated into one unit, which can be yanked all at once. Commands which do not kill text separate the chunks of text on the kill-ring.
Readline is customized by putting commands in an initializa- tion file. The name of this file is taken from the value of the INPUTRC variable. If that variable is unset, the default is ~/.inputrc. When a program which uses the read- line library starts up, the init file is read, and the key bindings and variables are set. 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. Other lines denote key bindings and variable settings. Each pro- gram using this library may add its own commands and bind- ings. For example, placing M-Control-u: universal-argument or C-Meta-u: universal-argument into the ~/.inputrc would make M-C-u execute the readline command universal-argument. The following symbolic character names are recognized while processing key bindings: RUBOUT, DEL, ESC, LFD, NEWLINE, RET, RETURN, SPC, SPACE, and TAB. In addition to command names, readline allows keys to be bound to a string that is inserted when the key is pressed (a macro). Key Bindings The syntax for controlling key bindings in the ~/.inputrc file is simple. All that is required is the name of the command or the text of a macro and a key sequence to which it should be bound. The name may be specified in one of two ways: as a symbolic key name, possibly with Meta- or Con- trol- prefixes, or as a key sequence. When using the form 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). In the second form, "keyseq":function-name or macro, keyseq differs from keyname above in that strings denoting an entire key sequence may be specified by placing the sequence within double quotes. Some GNU Emacs style key escapes can be used, as in the following example. "\C-u": universal-argument "\C-x\C-r": re-read-init-file "\e[11~": "Function Key 1" In this example, C-u is again bound to the function universal-argument. 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 full set of escape sequences is \C- control prefix \M- meta prefix \e an escape character \\ backslash " \" literal " \' literal ' When entering the text of a macro, single or double quotes should be used to indicate a macro definition. Unquoted text is assumed to be a function name. Backslash will quote any character in the macro text, including " and '. Bash allows the current readline key bindings to be displayed or modified with the bind builtin command. The editing mode may be switched during interactive use by using the -o option to the set builtin command. Other programs using this library provide similar mechanisms. The inputrc file may be edited and re-read if a program does not provide any other means to incorporate new bindings. Variables Readline has variables that can be used to further customize its behavior. A variable may be set in the inputrc file with a statement of the form set variable-name value Except where noted, readline variables can take the values On or Off. The variables and their default values are: horizontal-scroll-mode (Off) When set to On, makes readline use a single line for display, scrolling the input horizontally on a single screen line when it becomes longer than the screen width rather than wrapping to a new line. editing-mode (emacs) Controls whether readline begins with a set of key bindings similar to emacs or vi. editing-mode can be set to either emacs or vi. mark-modified-lines (Off) If set to On, history lines that have been modified are displayed with a preceding asterisk (*). bell-style (audible) 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, readline attempts to ring the terminal's bell. comment-begin (``#'') The string that is inserted in vi mode when the vi-comment command is executed. meta-flag (Off) If set to On, readline will enable eight-bit input (that is, it will not strip the high bit from the char- acters it reads), regardless of what the terminal claims it can support. convert-meta (On) If set to On, readline will convert characters with the eighth bit set to an ASCII key sequence by stripping the eighth bit and prepending an escape character (in effect, using escape as the meta prefix). output-meta (Off) If set to On, readline will display characters with the eighth bit set directly rather than as a meta-prefixed escape sequence. completion-query-items (100) This determines when the user is queried about viewing the number of possible completions generated by the possible-completions command. It may be set to any integer value greater than or equal to zero. If the number of possible completions is greater than or equal to the value of this variable, the user is asked whether or not he wishes to view them; otherwise they are simply listed on the terminal. keymap (emacs) Set the current readline keymap. The set of legal key- map names is emacs, emacs-standard, emacs-meta, emacs- ctlx, vi, vi-move, vi-command, and vi-insert. vi is equivalent to vi-command; emacs is equivalent to emacs-standard. The default value is emacs; the value of editing-mode also affects the default keymap. show-all-if-ambiguous (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. expand-tilde (Off) If set to on, tilde expansion is performed when read- line attempts word completion. Conditional Constructs Readline implements a facility similar in spirit to the con- ditional compilation features of the C preprocessor which allows key bindings and variable settings to be performed as the result of tests. There are three parser directives used. $if The $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 The 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 key- map command, for instance, to set bindings in the emacs-standard and emacs-ctlx keymaps only if readline is starting out in emacs mode. term The 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 the full name of the terminal and the por- tion of the terminal name before the first -. This allows sun to match both sun and sun-cmd, for instance. application The application construct is used to include application-specific settings. Each program using the readline library sets the application name, and an initialization file can test for a particu- lar value. This could be used to bind key sequences to functions useful for a specific pro- gram. For instance, the following command adds a key sequence that quotes the current or previous word in Bash: $if bash # Quote the current or previous word "\C-xq": "\eb\"\ef\"" $endif $endif This command, as you saw in the previous example, ter- minates an $if command. $else Commands in this branch of the $if directive are exe- cuted if the test fails.
The following is a list of the names of the commands and the default key sequences to which they are bound. Commands for Moving beginning-of-line (C-a) Move to the start of the current line. end-of-line (C-e) Move to the end of the line. forward-char (C-f) Move forward a character. backward-char (C-b) Move back a character. forward-word (M-f) Move forward to the end of the next word. Words are composed of alphanumeric characters (letters and digits). backward-word (M-b) Move back to the start of this, or the previous, word. Words are composed of alphanumeric characters (letters and digits). clear-screen (C-l) Clear the screen leaving the current line at the top of the screen. With an argument, refresh the current line without clearing the screen. redraw-current-line Refresh the current line. By default, this is unbound. Commands for Manipulating the History accept-line (Newline, Return) Accept the line regardless of where the cursor is. If this line is non-empty, add it to the history list. If the line is a modified history line, then restore the history line to its original state. previous-history (C-p) Fetch the previous command from the history list, mov- ing back in the list. next-history (C-n) Fetch the next command from the history list, moving forward in the list. beginning-of-history (M-<) Move to the first line in the history. end-of-history (M->) Move to the end of the input history, i.e., the line currently being entered. reverse-search-history (C-r) Search backward starting at the current line and moving `up' through the history as necessary. This is an incremental search. forward-search-history (C-s) Search forward starting at the current line and moving `down' through the history as necessary. This is an incremental search. non-incremental-reverse-search-history (M-p) Search backward through the history starting at the current line using a non-incremental search for a string supplied by the user. non-incremental-forward-search-history (M-n) Search forward through the history using a non-incremental search for a string supplied by the user. history-search-forward Search forward through the history for the string of characters between the start of the current line and the current point. This is a non-incremental search. By default, this command is unbound. history-search-backward Search backward through the history for the string of characters between the start of the current line and the current point. This is a non-incremental search. By default, this command is unbound. yank-nth-arg (M-C-y) Insert the first argument to the previous command (usu- ally the second word on the previous line) at point (the current cursor position). With an argument n, insert the nth word from the previous command (the words in the previous command begin with word 0). A negative argument inserts the nth word from the end of the previous command. yank-last-arg (M-., M-_) Insert the last argument to the previous command (the last word on the previous line). With an argument, behave exactly like yank-nth-arg. Commands for Changing Text delete-char (C-d) Delete the character under the cursor. If point is at the beginning of the line, there are no characters in the line, and the last character typed was not C-d, then return EOF. backward-delete-char (Rubout) Delete the character behind the cursor. When given a numeric argument, save the deleted text on the kill-ring. quoted-insert (C-q, C-v) Add the next character that you type to the line verba- tim. This is how to insert characters like C-q, for example. tab-insert (M-TAB) Insert a tab character. self-insert (a, b, A, 1, !, ...) Insert the character typed. transpose-chars (C-t) Drag the character before point forward over the char- acter at point. Point moves forward as well. If point is at the end of the line, then transpose the two char- acters before point. Negative arguments don't work. transpose-words (M-t) Drag the word behind the cursor past the word in front of the cursor moving the cursor over that word as well. upcase-word (M-u) Uppercase the current (or following) word. With a negative argument, do the previous word, but do not move point. downcase-word (M-l) Lowercase the current (or following) word. With a negative argument, do the previous word, but do not move point. capitalize-word (M-c) Capitalize the current (or following) word. With a negative argument, do the previous word, but do not move point. Killing and Yanking kill-line (C-k) Kill the text from the current cursor position to the end of the line. backward-kill-line (C-x Rubout) Kill backward to the beginning of the line. unix-line-discard (C-u) Kill backward from point to the beginning of the line. kill-whole-line Kill all characters on the current line, no matter where the cursor is. By default, this is unbound. kill-word (M-d) Kill from the cursor to the end of the current word, or if between words, to the end of the next word. Word boundaries are the same as those used by forward-word. backward-kill-word (M-Rubout) Kill the word behind the cursor. Word boundaries are the same as those used by backward-word. unix-word-rubout (C-w) Kill the word behind the cursor, using white space as a word boundary. The word boundaries are different from backward-kill-word. delete-horizontal-space Delete all spaces and tabs around point. By default, this is unbound. yank (C-y) Yank the top of the kill ring into the buffer at the cursor. yank-pop (M-y) Rotate the kill-ring, and yank the new top. Only works following yank or yank-pop. Numeric Arguments digit-argument (M-0, M-1, ..., M--) Add this digit to the argument already accumulating, or start a new argument. M-- starts a negative argument. universal-argument Each time this is executed, the argument count is mul- tiplied by four. The argument count is initially one, so executing this function the first time makes the argument count four. By default, this is not bound to a key. Completing complete (TAB) Attempt to perform completion on the text before point. The actual completion performed is application- specific. Bash, for instance, attempts completion treating the text as a variable (if the text begins with $), username (if the text begins with ~), hostname (if the text begins with @), or command (including aliases and functions) in turn. If none of these pro- duces a match, filename completion is attempted. Gdb, on the other hand, allows completion of program func- tions and variables, and only attempts filename comple- tion under certain circumstances. possible-completions (M-?) List the possible completions of the text before point. insert-completions Insert all completions of the text before point that would have been generated by possible-completions. By default, this is not bound to a key. Keyboard Macros start-kbd-macro (C-x () Begin saving the characters typed into the current key- board macro. end-kbd-macro (C-x )) Stop saving the characters typed into the current key- board macro and save the definition. call-last-kbd-macro (C-x e) Re-execute the last keyboard macro defined, by making the characters in the macro appear as if typed at the keyboard. Miscellaneous re-read-init-file (C-x C-r) Read in the contents of your init file, and incorporate any bindings or variable assignments found there. abort (C-g) Abort the current editing command and ring the terminal's bell (subject to the setting of bell-style). do-uppercase-version (M-a, M-b, ...) Run the command that is bound to the corresponding uppercase character. prefix-meta (ESC) Metafy the next character typed. ESC f is equivalent to Meta-f. undo (C-_, C-x C-u) Incremental undo, separately remembered for each line. revert-line (M-r) Undo all changes made to this line. This is like typ- ing the undo command enough times to return the line to its initial state. tilde-expand (M-~) Perform tilde expansion on the current word. dump-functions Print all of the functions and their key bindings to the readline output stream. If a numeric argument is supplied, the output is formatted in such a way that it can be made part of an inputrc file. emacs-editing-mode (C-e) When in vi editing mode, this causes a switch to emacs editing mode. vi-editing-mode (M-C-j) When in emacs editing mode, this causes a switch to vi editing mode.
DEFAULT KEY BINDINGS
The following is a list of the default emacs and vi bind- ings. Characters with the 8th bit set are written as M- <character>, and are referred to as metafied characters. The printable ASCII characters not mentioned in the list of emacs standard bindings are bound to the self-insert func- tion, which just inserts the given character into the input line. In vi insertion mode, all characters not specifically mentioned are bound to self-insert. Characters assigned to signal generation by stty(1) or the terminal driver, such as C-Z or C-C, retain that function. Upper and lower case metafied characters are bound to the same function in the emacs mode meta keymap. The remaining characters are unbound, which causes readline to ring the bell (subject to the setting of the bell-style variable). Emacs Mode Emacs Standard bindings "C-A" -> beginning-of-line "C-B" -> backward-char "C-D" -> delete-char "C-E" -> end-of-line "C-F" -> forward-char "C-G" -> abort "C-H" -> backward-delete-char "C-I" -> complete "C-J" -> accept-line "C-K" -> kill-line "C-L" -> clear-screen "C-M" -> accept-line "C-N" -> next-history "C-P" -> previous-history "C-Q" -> quoted-insert "C-R" -> reverse-search-history "C-S" -> forward-search-history "C-T" -> transpose-chars "C-U" -> unix-line-discard "C-V" -> quoted-insert "C-W" -> unix-word-rubout "C-Y" -> yank "C-_" -> undo " " to "/" -> self-insert "0" to "9" -> self-insert ":" to "~" -> self-insert "C-?" -> backward-delete-char Emacs Meta bindings "M-C-H" -> backward-kill-word "M-C-I" -> tab-insert "M-C-J" -> vi-editing-mode "M-C-M" -> vi-editing-mode "M-C-R" -> revert-line "M-C-Y" -> yank-nth-arg "M-C-[" -> complete "M-&" -> tilde-expand "M--" -> digit-argument "M-0" -> digit-argument "M-1" -> digit-argument "M-2" -> digit-argument "M-3" -> digit-argument "M-4" -> digit-argument "M-5" -> digit-argument "M-6" -> digit-argument "M-7" -> digit-argument "M-8" -> digit-argument "M-9" -> digit-argument "M-<" -> beginning-of-history "M->" -> end-of-history "M-?" -> possible-completions "M-B" -> backward-word "M-C" -> capitalize-word "M-D" -> kill-word "M-F" -> forward-word "M-L" -> downcase-word "M-N" -> non-incremental-forward-search-history "M-O" -> arrow-key-prefix "M-P" -> non-incremental-reverse-search-history "M-R" -> revert-line "M-T" -> transpose-words "M-U" -> upcase-word "M-Y" -> yank-pop "M-C-Y" -> yank-nth-arg "M-C-?" -> backward-delete-word Emacs Control-X bindings "C-XC-G" -> abort "C-XC-R" -> re-read-init-file "C-XC-U" -> undo "C-X(" -> start-kbd-macro "C-X)" -> end-kbd-macro "C-Xe" -> call-last-kbd-macro "C-XC-?" -> backward-kill-line VI Mode bindings VI Insert Mode functions "C-D" -> vi-eof-maybe "C-H" -> backward-delete-char "C-I" -> complete "C-J" -> accept-line "C-K" -> kill-line "C-L" -> clear-screen "C-M" -> accept-line "C-N" -> next-history "C-P" -> previous-history "C-Q" -> quoted-insert "C-R" -> reverse-search-history "C-S" -> forward-search-history "C-T" -> transpose-chars "C-U" -> unix-line-discard "C-V" -> quoted-insert "C-W" -> unix-word-rubout "C-Y" -> yank "C-[" -> vi-movement-mode " " to "~" -> self-insert "C-?" -> backward-delete-char VI Command Mode functions "C-D" -> vi-eof-maybe "C-E" -> emacs-editing-mode "C-G" -> abort "C-H" -> backward-char "C-J" -> accept-line "C-K" -> kill-line "C-L" -> clear-screen "C-M" -> accept-line "C-N" -> next-history "C-P" -> previous-history "C-Q" -> quoted-insert "C-R" -> reverse-search-history "C-S" -> forward-search-history "C-T" -> transpose-chars "C-U" -> unix-line-discard "C-V" -> quoted-insert "C-W" -> unix-word-rubout "C-Y" -> yank "C-[" -> abort " " -> forward-char "#" -> vi-comment "$" -> end-of-line "%" -> vi-match "&" -> vi-tilde-expand "*" -> vi-complete "+" -> down-history "," -> vi-char-search "-" -> previous-history "." -> vi-redo "/" -> vi-search "0" -> beginning-of-line "1" to "9" -> vi-arg-digit ";" -> vi-char-search "=" -> vi-complete "?" -> vi-search "@" -> is undefined "A" -> vi-append-eol "B" -> vi-prev-word "C" -> vi-change-to "D" -> vi-delete-to "E" -> vi-end-word "F" -> vi-char-search "I" -> vi-insert-beg "N" -> vi-search-again "P" -> vi-put "R" -> vi-replace "S" -> vi-subst "T" -> vi-char-search "U" -> revert-line "W" -> vi-next-word "X" -> backward-delete-char "Y" -> vi-yank-to "\" -> vi-complete "^" -> vi-first-print "_" -> vi-yank-arg "a" -> vi-append-mode "b" -> vi-prev-word "c" -> vi-change-to "d" -> vi-delete-to "e" -> vi-end-word "f" -> vi-char-search "h" -> backward-char "i" -> vi-insertion-mode "j" -> next-history "k" -> prev-history "l" -> forward-char "n" -> vi-search-again "r" -> vi-change-char "s" -> vi-subst "t" -> vi-char-search "u" -> undo "w" -> vi-next-word "x" -> vi-delete "y" -> vi-yank-to "|" -> vi-column "~" -> vi-change-case
The Gnu Readline Library, Brian Fox and Chet Ramey The Gnu History Library, Brian Fox and Chet Ramey bash(1)
~/.inputrc Individual readline initialization file
Brian Fox, Free Software Foundation (primary author) Chet Ramey, Case Western Reserve University
If you find a bug in readline, you should report it. But first, you should make sure that it really is a bug, and that it appears in the latest version of the readline library that you have. Once you have determined that a bug actually exists, mail a bug report to email@example.com.MIT.Edu. If you have a fix, you are welcome to mail that as well! Suggestions and `philosophical' bug reports may be mailed to bug- firstname.lastname@example.org.MIT.Edu or posted to the Usenet newsgroup gnu.bash.bug. Comments and bug reports concerning this manual page should be directed to chet@ins.CWRU.Edu.
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