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1 JohnMcPherson 1 !!BASH MAN PAGE (Part 6)
2
3 __Navigation__%%%
4 This man page has been split into 7 pages:%%%
5 bash(1)
6 * NAME
7 * SYNOPSIS
8 * COPYRIGHT
9 * DESCRIPTION
10 * OPTIONS
11 * ARGUMENTS
12 * INVOCATION
13
14 [bash(1)Part2]
15 * DEFINITIONS
16 * RESERVED WORDS
17 * SHELL GRAMMAR
18 * COMMENTS
19 * QUOTING
20
21 [bash(1)Part3]
22 * PARAMETERS
23
24 [bash(1)Part4]
25 * EXPANSION
26
27 [bash(1)Part5]
28 * REDIRECTION
29 * ALIASES
30 * FUNCTIONS
31 * ARITHMETIC EVALUATION
32 * CONDITIONAL EXPRESSIONS
33 * SIMPLE COMMAND EXPANSION
34 * COMMAND EXECUTION
35 * COMMAND EXECUTION ENVIRONMENT
36 * ENVIRONMENT
37 * EXIT STATUS
38 * SIGNALS
39 * JOB CONTROL
40 * PROMPTING
41
42 __Part6__
43 * __READLINE__
44 * __HISTORY__
45 * __HISTORY EXPANSION__
46
47
48 [bash(1)Part7]
49 * SHELL BUILTIN COMMANDS
50 * RESTRICTED SHELL
51 * SEE ALSO
52 * FILES
53 * AUTHORS
54 * BUG REPORTS
55 * BUGS
56
57 ----
58 !!READLINE
59 This is the library that handles reading input when using an interactive shell, unless the __-noediting__ option is given at shell invocation. By default, the line editing commands are similar to those of emacs. A vi-style line editing interface is also available. To turn off line editing after the shell is running, use the __+o emacs__ or __+o vi__ options to the __set__ builtin (see __SHELL BUILTIN COMMANDS__ below).
60
61 !"Readline Notation"
62
63
64 In this section, the emacs-style notation is used to denote keystrokes. Control 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.)
65
66 Readline commands may be given numeric ''arguments'' , which normally act as a repeat count. Sometimes, however, it is the sign of the argument that is significant. Passing a negative argument to a command that acts in the forward direction (e.g., __kill-line__) causes that command to act in a backward direction. Commands whose behavior with arguments deviates from this are noted below.
67
68 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.
69
70 !"Readline Initialization"
71
72
73 Readline is customized by putting commands in an initialization file (the ''inputrc'' 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 readline library starts up, the initialization file is read, and the key bindings and variables are set. There are only a few basic constructs allowed in the readline initialization 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.
74
75 The default key-bindings may be changed with an ''inputrc '' file. Other programs that use this library may add their own commands and bindings.
76
77 For example, placing
78
79 M-Control-u: universal-argument
80 or
81 C-Meta-u: universal-argument
82 into the ''inputrc'' would make M-C-u execute the readline command ''universal-argument'' .
83
84 The following symbolic character names are recognized: ''RUBOUT'' , ''DEL'' , ''ESC'' , ''LFD'' , ''NEWLINE'' , ''RET'' , ''RETURN'' , ''SPC'' , ''SPACE'' , and ''TAB'' .
85
86 In addition to command names, readline allows keys to be bound to a string that is inserted when the key is pressed (a ''macro'').
87
88 !"Readline Key Bindings"
89
90
91 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 ''Control-'' prefixes, or as a key sequence.
92
93 When using the form __keyname__:''function-name'' or ''macro'', ''keyname'' is the name of a key spelled out in English. For example:
94
95
96 Control-u: universal-argument
97 Meta-Rubout: backward-kill-word
98 Control-o: "> output"
99
100
101 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
102 "> output"into the line).
103
104 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, but the symbolic character names are not recognized.
105
106
107 "\C-u": universal-argument
108 "\C-x\C-r": re-read-init-file
109 "\e[[11~": "Function Key 1"
110
111
112 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
113 "Function Key 1".
114
115 The full set of GNU Emacs style escape sequences is
116
117
118 ;__\C-__ : control prefix
119 ;__\M-__ : meta prefix
120 ;__\e__ : an escape character
121 ;__\\e__ : backslash
122 ;__\"__ : literal "
123 ;__\'__ : literal '
124
125
126
127
128 In addition to the GNU Emacs style escape sequences, a second set of backslash escapes is available:
129
130
131 ;__\a__ : alert (bell)
132 ;__\b__ : backspace
133 ;__\d__ : delete
134 ;__\f__ : form feed
135 ;__\n__ : newline
136 ;__\r__ : carriage return
137 ;__\t__ : horizontal tab
138 ;__\v__ : vertical tab
139 ;__\''nnn''__ : the character whose ASCII code is the octal value ''nnn'' (one to three digits)
140 ;__\x''nnn''__ : the character whose ASCII code is the hexadecimal value ''nnn'' (one to three digits)
141
142
143
144
145 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 '.
146
147 __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 (see __SHELL BUILTIN COMMANDS__ below).
148
149 !"Readline Variables"
150
151
152 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
153
154 __set__ ''variable-name'' ''value''
155
156
157 Except where noted, readline variables can take the values __On__ or __Off__ . The variables and their default values are:
158
159
160 ;__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.
161 ;__comment-begin ("#")__ : The string that is inserted when the readline __insert-comment__ command is executed. This command is bound to __M-#__ in emacs mode and to __#__ in vi command mode.
162 ;__completion-ignore-case (Off)__ : If set to __On__, readline performs filename matching and completion in a case-insensitive fashion.
163 ;__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.
164 ;__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 prefixing an escape character (in effect, using escape as the ''meta prefix'').
165 ;__disable-completion (Off)__ : 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__.
166 ;__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__ .
167 ;__enable-keypad (Off)__ : 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.
168 ;__expand-tilde (Off)__ : If set to __on__, tilde expansion is performed when readline attempts word completion.
169 ;__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.
170 ;__input-meta (Off)__ : If set to __On__, readline will enable eight-bit input (that is, it will not strip the high bit from the characters it reads), regardless of what the terminal claims it can support. The name __meta-flag__ is a synonym for this variable.
171 ;__isearch-terminators ("C-[[C-J")__ : The string of characters that should terminate an incremental search without subsequently executing the character as a command. If this variable has not been given a value, the characters ''ESC'' and ''C-J'' will terminate an incremental search.
172 ;__keymap (emacs)__ : Set the current readline keymap. The set of valid keymap names is ''emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, 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.
173 ;__mark-directories (On)__ : If set to __On__, completed directory names have a slash appended.
174 ;__mark-modified-lines (Off)__ : If set to __On__, history lines that have been modified are displayed with a preceding asterisk (__*__).
175 ;__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.
176 ;__print-completions-horizontally (Off)__ : If set to __On__, readline will display completions with matches sorted horizontally in alphabetical order, rather than down the screen.
177 ;__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.
178 ;__visible-stats (Off)__ : If set to __On__, a character denoting a file's type as reported by ''stat''(2) is appended to the filename when listing possible completions.
179
180
181
182 !"Readline Conditional Constructs"
183
184
185 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.
186 ;__$if__: The __$if__ construct allows bindings to be made based on the editing mode, the terminal being used, or the application using readline. The text of the test extends to the end of the line; no characters are required to isolate it.
187
188 ;__mode__: The __mode=__ form of the __$if__ directive is used to test whether readline is in emacs or vi mode. This may be used in conjunction with the __set keymap__ command, for instance, to set bindings in the ''emacs-standard'' and ''emacs-ctlx'' keymaps only if readline is starting out in emacs mode.
189 ;__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 both 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.
190 ;__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 particular value. This could be used to bind key sequences to functions useful for a specific program. For instance, the following command adds a key sequence that quotes the current or previous word in Bash:
191
192
193
194 __$if__ Bash
195 # Quote the current or previous word
196 "\C-xq": "\eb\"\ef\""
197 __$endif__
198
199
200 ;__$endif__: This command, as seen in the previous example, terminates an __$if__ command.
201 ;__$else__: Commands in this branch of the __$if__ directive are executed if the test fails.
202 ;__$include__: This directive takes a single filename as an argument and reads commands and bindings from that file. For example, the following directive would read ''/etc/inputrc'':
203
204 __$include__ ''/etc/inputrc''
205
206
207 !Searching
208
209
210 Readline provides commands for searching through the command history (see __HISTORY__ below) for lines containing a specified string. There are two search modes: ''incremental'' and ''non-incremental'' .
211
212 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. 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 Escape and Control-J characters will terminate an incremental search. Control-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.
213
214 To find other matching entries in the history list, type Control-S or Control-R 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 ''newline'' will terminate the search and accept the line, thereby executing the command from the history list.
215
216 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.
217
218 !"Readline Command Names"
219
220
221 The following is a list of the names of the commands and the default key sequences to which they are bound. 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''.
222
223 !Commands for Moving
224
225
226
227
228
229 ;__beginning-of-line (C-a)__ : Move to the start of the current line.
230 ;__end-of-line (C-e)__ : Move to the end of the line.
231 ;__forward-char (C-f)__ : Move forward a character.
232 ;__backward-char (C-b)__ : Move back a character.
233 ;__forward-word (M-f)__ : Move forward to the end of the next word. Words are composed of alphanumeric characters (letters and digits).
234 ;__backward-word (M-b)__ : Move back to the start of the current or previous word. Words are composed of alphanumeric characters (letters and digits).
235 ;__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.
236 ;__redraw-current-line__ : Refresh the current line.
237
238
239
240 !Commands for Manipulating the History
241
242
243 ;__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 according to the state of the __HISTCONTROL__ variable. If the line is a modified history line, then restore the history line to its original state.
244 ;__previous-history (C-p)__ : Fetch the previous command from the history list, moving back in the list.
245 ;__next-history (C-n)__ : Fetch the next command from the history list, moving forward in the list.
246 ;__beginning-of-history (M-<)__ : Move to the first line in the history.
247 ;__end-of-history (M->)__ : Move to the end of the input history, i.e., the line currently being entered.
248 ;__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.
249 ;__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.
250 ;__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.
251 ;__non-incremental-forward-search-history (M-n)__ : Search forward through the history using a non-incremental search for a string supplied by the user.
252 ;__history-search-forward__ : Search forward through the history for the string of characters between the start of the current line and the point. This is a non-incremental search.
253 ;__history-search-backward__ : Search backward through the history for the string of characters between the start of the current line and the point. This is a non-incremental search.
254 ;__yank-nth-arg (M-C-y)__ : Insert the first argument to the previous command (usually the second word on the previous line) at point. With an argument ''n'' , insert the ''n''th word from the previous command (the words in the previous command begin with word 0). A negative argument inserts the ''n''th word from the end of the previous command.
255 ;.B : yank-last-arg (M-., M-_) Insert the last argument to the previous command (the last word of the previous history entry). With an argument, behave exactly like __yank-nth-arg__. Successive calls to __yank-last-arg__ move back through the history list, inserting the last argument of each line in turn.
256 ;__shell-expand-line (M-C-e)__ : Expand the line as the shell does. This performs alias and history expansion as well as all of the shell word expansions. See __HISTORY EXPANSION__ below for a description of history expansion.
257 ;__history-expand-line (M-^)__ : Perform history expansion on the current line. See __HISTORY EXPANSION__ below for a description of history expansion.
258 ;__magic-space__ : Perform history expansion on the current line and insert a space. See __HISTORY EXPANSION__ below for a description of history expansion.
259 ;__alias-expand-line__ : Perform alias expansion on the current line. See __ALIASES__ above for a description of alias expansion.
260 ;__history-and-alias-expand-line__ : Perform history and alias expansion on the current line.
261 ;__insert-last-argument (M-., M-_)__ : A synonym for __yank-last-arg__.
262 ;__operate-and-get-next (C-o)__ : Accept the current line for execution and fetch the next line relative to the current line from the history for editing. Any argument is ignored.
263
264
265
266 !Commands for Changing Text
267
268
269
270 ;__delete-char (C-d)__ : Delete the character at point. If point is at the beginning of the line, there are no characters in the line, and the last character typed was not bound to __delete-char__, then return __EOF__ .
271 ;__backward-delete-char (Rubout)__ : Delete the character behind the cursor. When given a numeric argument, save the deleted text on the kill ring.
272 ;__forward-backward-delete-char__ : Delete the character under the cursor, unless the cursor is at the end of the line, in which case the character behind the cursor is deleted. By default, this is not bound to a key.
273 ;__quoted-insert (C-q, C-v)__ : Add the next character typed to the line verbatim. This is how to insert characters like __C-q__, for example.
274 ;__tab-insert (C-v TAB)__ : Insert a tab character.
275 ;__self-insert (a,\ b,\ A,\ 1,\ !,\ ...)__ : Insert the character typed.
276 ;__transpose-chars (C-t)__ : Drag the character before point forward over the character at point, moving point forward as well. If point is at the end of the line, then this transposes the two characters before point. Negative arguments have no effect.
277 ;__transpose-words (M-t)__ : Drag the word before point past the word after point, moving point over that word as well.
278 ;__upcase-word (M-u)__ : Uppercase the current (or following) word. With a negative argument, uppercase the previous word, but do not move point.
279 ;__downcase-word (M-l)__ : Lowercase the current (or following) word. With a negative argument, lowercase the previous word, but do not move point.
280 ;__capitalize-word (M-c)__ : Capitalize the current (or following) word. With a negative argument, capitalize the previous word, but do not move point.
281
282
283
284 !Killing and Yanking
285
286
287
288 ;__kill-line (C-k)__ : Kill the text from point to the end of the line.
289 ;__backward-kill-line (C-x Rubout)__ : Kill backward to the beginning of the line.
290 ;__unix-line-discard (C-u)__ : Kill backward from point to the beginning of the line. The killed text is saved on the kill-ring.
291 ;__kill-whole-line__ : Kill all characters on the current line, no matter where point is.
292 ;__kill-word (M-d)__ : Kill from point 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__.
293 ;__backward-kill-word (M-Rubout)__ : Kill the word behind point. Word boundaries are the same as those used by __backward-word__.
294 ;__unix-word-rubout (C-w)__ : Kill the word behind point, using white space as a word boundary. The killed text is saved on the kill-ring.
295 ;__delete-horizontal-space (M-\)__ : Delete all spaces and tabs around point.
296 ;__kill-region__ : Kill the text in the current region.
297 ;__copy-region-as-kill__ : Copy the text in the region to the kill buffer.
298 ;__copy-backward-word__ : Copy the word before point to the kill buffer. The word boundaries are the same as __backward-word__.
299 ;__copy-forward-word__ : Copy the word following point to the kill buffer. The word boundaries are the same as __forward-word__.
300 ;__yank (C-y)__ : Yank the top of the kill ring into the buffer at point.
301 ;__yank-pop (M-y)__ : Rotate the kill ring, and yank the new top. Only works following __yank__ or __yank-pop__ .
302
303
304
305 !Numeric Arguments
306
307
308
309
310
311 ;__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.
312 ;__universal-argument__ : This is another way to specify an argument. If this command is followed by one or more digits, optionally with a leading minus sign, those digits define the argument. If the command is followed by digits, executing __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 or 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.
313
314
315
316 !Completing
317
318
319
320 ;__complete (TAB)__ : Attempt to perform completion on the text before point. __Bash__ attempts completion treating the text as a variable (if the text begins with __$__), username (if the text begins with __~__), hostname (if the text begins with __@__), or command (including aliases and functions) in turn. If none of these produces a match, filename completion is attempted.
321 ;__possible-completions (M-?)__ : List the possible completions of the text before point.
322 ;__insert-completions (M-*)__ : Insert all completions of the text before point that would have been generated by __possible-completions__.
323 ;__menu-complete__ : Similar to __complete__, but replaces the word to be completed with a single match from the list of possible completions. Repeated execution of __menu-complete__ steps through the list of possible completions, inserting each match in turn. At the end of the list of completions, the bell is rung (subject to the setting of \Bbell-style) and the original text is restored. An argument of ''n'' moves ''n'' positions forward in the list of matches; a negative argument may be used to move backward through the list. This command is intended to be bound to __TAB__, but is unbound by default.
324 ;__delete-char-or-list__ : Deletes the character under the cursor if not at the beginning or end of the line (like __delete-char__). If at the end of the line, behaves identically to __possible-completions__. This command is unbound by default.
325 ;__complete-filename (M-/)__ : Attempt filename completion on the text before point.
326 ;__possible-filename-completions (C-x /)__ : List the possible completions of the text before point, treating it as a filename.
327 ;__complete-username (M-~)__ : Attempt completion on the text before point, treating it as a username.
328 ;__possible-username-completions (C-x ~)__ : List the possible completions of the text before point, treating it as a username.
329 ;__complete-variable (M-$)__ : Attempt completion on the text before point, treating it as a shell variable.
330 ;__possible-variable-completions (C-x $)__ : List the possible completions of the text before point, treating it as a shell variable.
331 ;__complete-hostname (M-@)__ : Attempt completion on the text before point, treating it as a hostname.
332 ;__possible-hostname-completions (C-x @)__ : List the possible completions of the text before point, treating it as a hostname.
333 ;__complete-command (M-!)__ : Attempt completion on the text before point, treating it as a command name. Command completion attempts to match the text against aliases, reserved words, shell functions, shell builtins, and finally executable filenames, in that order.
334 ;__possible-command-completions (C-x !)__ : List the possible completions of the text before point, treating it as a command name.
335 ;__dynamic-complete-history (M-TAB)__ : Attempt completion on the text before point, comparing the text against lines from the history list for possible completion matches.
336 ;__complete-into-braces (M-{)__ : Perform filename completion and insert the list of possible completions enclosed within braces so the list is available to the shell (see __Brace Expansion__ above).
337
338
339 !Keyboard Macros
340
341
342
343
344
345 ;__start-kbd-macro (C-x ()__ : Begin saving the characters typed into the current keyboard macro.
346 ;__end-kbd-macro (C-x ))__ : Stop saving the characters typed into the current keyboard macro and store the definition.
347 ;__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.
348
349
350
351 !Miscellaneous
352
353
354
355
356
357 ;__re-read-init-file (C-x C-r)__ : Read in the contents of the ''inputrc'' file, and incorporate any bindings or variable assignments found there.
358 ;__abort (C-g)__ : Abort the current editing command and ring the terminal's bell (subject to the setting of __bell-style__ ).
359 ;__do-uppercase-version (M-a, M-b, M-''x'', ...)__ : If the metafied character ''x'' is lowercase, run the command that is bound to the corresponding uppercase character.
360 ;__prefix-meta (ESC)__ : Metafy the next character typed. __ESC__ __f__ is equivalent to __Meta-f__ .
361 ;__undo (C-_, C-x C-u)__ : Incremental undo, separately remembered for each line.
362 ;__revert-line (M-r)__ : Undo all changes made to this line. This is like executing the __undo__ command enough times to return the line to its initial state.
363 ;__tilde-expand (M-&)__ : Perform tilde expansion on the current word.
364 ;__set-mark (C-@, M-<space>)__ : Set the mark to the point. If a numeric argument is supplied, the mark is set to that position.
365 ;__exchange-point-and-mark (C-x C-x)__ : Swap the point with the mark. The current cursor position is set to the saved position, and the old cursor position is saved as the mark.
366 ;__character-search (C-])__ : A character is read and point is moved to the next occurrence of that character. A negative count searches for previous occurrences.
367 ;__character-search-backward (M-C-])__ : A character is read and point is moved to the previous occurrence of that character. A negative count searches for subsequent occurrences.
368 ;__insert-comment (M-#)__ : The value of the readline __comment-begin__ variable is inserted at the beginning of the current line, and the line is accepted as if a newline had been typed. The default value of __comment-begin__ causes this command to make the current line a shell comment.
369 ;__glob-expand-word (C-x *)__ : The word before point is treated as a pattern for pathname expansion, and the list of matching file names is inserted, replacing the word.
370 ;__glob-list-expansions (C-x g)__ : The list of expansions that would have been generated by __glob-expand-word__ is displayed, and the line is redrawn.
371 ;__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.
372 ;__dump-variables__ : Print all of the settable readline variables and their values 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.
373 ;__dump-macros__ : Print all of the readline key sequences bound to macros and the strings they ouput. If a numeric argument is supplied, the output is formatted in such a way that it can be made part of an ''inputrc'' file.
374 ;__display-shell-version (C-x C-v)__ : Display version information about the current instance of __bash__ .
375
376
377
378 !Programmable Completion
379
380
381 When word completion is attempted for an argument to a command for which a completion specification (a ''compspec'') has been defined using the __complete__ builtin (see __SHELL BUILTIN COMMANDS__ below), the programmable completion facilities are invoked.
382
383 First, the command name is identified. If a compspec has been defined for that command, the compspec is used to generate the list of possible completions for the word. If the command word is a full pathname, a compspec for the full pathname is searched for first. If no compspec is found for the full pathname, an attempt is made to find a compspec for the portion following the final slash.
384
385 Once a compspec has been found, it is used to generate the list of matching words. If a compspec is not found, the default __bash__ completion as described above under __Completing__ is performed.
386
387 First, the actions specified by the compspec are used. Only matches which are prefixed by the word being completed are returned. When the __-f__ or __-d__ option is used for filename or directory name completion, the shell variable __FIGNORE__ is used to filter the matches.
388
389 Any completions specified by a filename expansion pattern to the __-G__ option are generated next. The words generated by the pattern need not match the word being completed. The __GLOBIGNORE__ shell variable is not used to filter the matches, but the __FIGNORE__ variable is used.
390
391 Next, the string specified as the argument to the __-W__ option is considered. The string is first split using the characters in the __IFS__ special variable as delimiters. Shell quoting is honored. Each word is then expanded using brace expansion, tilde expansion, parameter and variable expansion, command substitution, arithmetic expansion, and pathname expansion, as described above under __EXPANSION__ . The results are split using the rules described above under __Word Splitting__. The results of the expansion are prefix-matched against the word being completed, and the matching words become the possible completions.
392
393 After these matches have been generated, any shell function or command specified with the __-F__ and __-C__ options is invoked. When the command or function is invoked, the __COMP_LINE__ and __COMP_POINT__ variables are assigned values as described above under __Shell Variables__. If a shell function is being invoked, the __COMP_WORDS__ and __COMP_CWORD__ variables are also set. When the function or command is invoked, the first argument is the name of the command whose arguments are being completed, the second argument is the word being completed, and the third argument is the word preceding the word being completed on the current command line. No filtering of the generated completions against the word being completed is performed; the function or command has complete freedom in generating the matches.
394
395 Any function specified with __-F__ is invoked first. The function may use any of the shell facilities, including the __compgen__ builtin described below, to generate the matches. It must put the possible completions in the __COMPREPLY__ array variable.
396
397 Next, any command specified with the __-C__ option is invoked in an environment equivalent to command substitution. It should print a list of completions, one per line, to the standard output. Backslash may be used to escape a newline, if necessary.
398
399 After all of the possible completions are generated, any filter specified with the __-X__ option is applied to the list. The filter is a pattern as used for pathname expansion; a __&__ in the pattern is replaced with the text of the word being completed. A literal __&__ may be escaped with a backslash; the backslash is removed before attempting a match. Any completion that matches the pattern will be removed from the list. A leading __!__ negates the pattern; in this case any completion not matching the pattern will be removed.
400
401 Finally, any prefix and suffix specified with the __-P__ and __-S__ options are added to each member of the completion list, and the result is returned to the readline completion code as the list of possible completions.
402
403 If the previously-applied actions do not generate any matches, and the __-o dirnames__ option was supplied to __complete__ when the compspec was defined, directory name completion is attempted.
404
405 By default, if a compspec is found, whatever it generates is returned to the completion code as the full set of possible completions. The default __bash__ completions are not attempted, and the readline default of filename completion is disabled. If the __-o default__ option was supplied to __complete__ when the compspec was defined, readline's default completion will be performed if the compspec generates no matches.
406
407
408
409 !!HISTORY
410 When the __-o history__ option to the __set__ builtin is enabled, the shell provides access to the ''command history'', the list of commands previously typed. The value of the __HISTSIZE__ variable is used as the number of commands to save in a history list. The text of the last __HISTSIZE__ commands (default 500) is saved. The shell stores each command in the history list prior to parameter and variable expansion (see __EXPANSION__ above) but after history expansion is performed, subject to the values of the shell variables __HISTIGNORE__ and __HISTCONTROL__ .
411
412 On startup, the history is initialized from the file named by the variable __HISTFILE__ (default ''~/.bash_history''). The file named by the value of __HISTFILE__ is truncated, if necessary, to contain no more than the number of lines specified by the value of __HISTFILESIZE__ . When an interactive shell exits, the last __$HISTSIZE__ lines are copied from the history list to __$HISTFILE__ . If the __histappend__ shell option is enabled (see the description of __shopt__ under __SHELL BUILTIN COMMANDS__ below), the lines are appended to the history file, otherwise the history file is overwritten. If __HISTFILE__ is unset, or if the history file is unwritable, the history is not saved. After saving the history, the history file is truncated to contain no more than __HISTFILESIZE__ lines. If __HISTFILESIZE__ is not set, no truncation is performed.
413
414 The builtin command __fc__ (see __SHELL BUILTIN COMMANDS__ below) may be used to list or edit and re-execute a portion of the history list. The __history__ builtin may be used to display or modify the history list and manipulate the history file. When using command-line editing, search commands are available in each editing mode that provide access to the history list.
415
416 The shell allows control over which commands are saved on the history list. The __HISTCONTROL__ and __HISTIGNORE__ variables may be set to cause the shell to save only a subset of the commands entered. The __cmdhist__ shell option, if enabled, causes the shell to attempt to save each line of a multi-line command in the same history entry, adding semicolons where necessary to preserve syntactic correctness. The __lithist__ shell option causes the shell to save the command with embedded newlines instead of semicolons. See the description of the __shopt__ builtin below under __SHELL BUILTIN COMMANDS__ for information on setting and unsetting shell options.
417
418 !!HISTORY EXPANSION
419
420
421 The shell supports a history expansion feature that is similar to the history expansion in __csh.__ This section describes what syntax features are available. This feature is enabled by default for interactive shells, and can be disabled using the __+H__ option to the __set__ builtin command (see __SHELL BUILTIN COMMANDS__ below). Non-interactive shells do not perform history expansion by default.
422
423 History expansions introduce words from the history list into the input stream, making it easy to repeat commands, insert the arguments to a previous command into the current input line, or fix errors in previous commands quickly.
424
425 History expansion is performed immediately after a complete line is read, before the shell breaks it into words. It takes place in two parts. The first is to determine which line from the history list to use during substitution. The second is to select portions of that line for inclusion into the current one. The line selected from the history is the ''event'', and the portions of that line that are acted upon are ''words''. Various ''modifiers'' are available to manipulate the selected words. The line is broken into words in the same fashion as when reading input, so that several ''metacharacter''-separated words surrounded by quotes are considered one word. History expansions are introduced by the appearance of the history expansion character, which is __!__ by default. Only backslash (__\__) and single quotes can quote the history expansion character.
426
427 Several shell options settable with the __shopt__ builtin may be used to tailor the behavior of history expansion. If the __histverify__ shell option is enabled (see the description of the __shopt__ builtin), and __readline__ is being used, history substitutions are not immediately passed to the shell parser. Instead, the expanded line is reloaded into the __readline__ editing buffer for further modification. If __readline__ is being used, and the __histreedit__ shell option is enabled, a failed history substitution will be reloaded into the __readline__ editing buffer for correction. The __-p__ option to the __history__ builtin command may be used to see what a history expansion will do before using it. The __-s__ option to the __history__ builtin may be used to add commands to the end of the history list without actually executing them, so that they are available for subsequent recall.
428
429 The shell allows control of the various characters used by the history expansion mechanism (see the description of __histchars__ above under __Shell Variables__ ).
430
431 !Event Designators
432
433
434 An event designator is a reference to a command line entry in the history list.
435
436
437
438 ;__!__ : Start a history substitution, except when followed by a __blank__ , newline, = or (.
439 ;__!''n''__ : Refer to command line ''n'' .
440 ;__!-''n''__ : Refer to the current command line minus ''n'' .
441 ;__!!__ : Refer to the previous command. This is a synonym for `!-1'.
442 ;__!''string''__ : Refer to the most recent command starting with ''string'' .
443 ;__!?''string''__[[?]____ : Refer to the most recent command containing ''string'' . The trailing __?__ may be omitted if ''string'' is followed immediately by a newline.
444 ;__\d\s+2^\s-2\u''string1''\d\s+2^\s-2\u''string2''\d\s+2^\s-2\u__ : Quick substitution. Repeat the last command, replacing ''string1'' with ''string2'' . Equivalent to ``!!:s/''string1''/''string2''/" (see __Modifiers__ below).
445 ;__!#__ : The entire command line typed so far.
446
447
448
449 !Word Designators
450
451
452 Word designators are used to select desired words from the event. A __:__ separates the event specification from the word designator. It may be omitted if the word designator begins with a __^__ , __$__ , __*__ , __-__ , or __%__ . Words are numbered from the beginning of the line, with the first word being denoted by 0 (zero). Words are inserted into the current line separated by single spaces.
453
454
455
456
457 ;__0 (zero)__ : The zeroth word. For the shell, this is the command word.
458 ;''n'' : The ''n''th word.
459 ;__^__ : The first argument. That is, word 1.
460 ;__$__ : The last argument.
461 ;__%__ : The word matched by the most recent `?''string''?' search.
462 ;''x__-__y'' : A range of words; `-''y''' abbreviates `0-''y'''.
463 ;__*__ : All of the words but the zeroth. This is a synonym for `''1-$'''. It is not an error to use __*__ if there is just one word in the event; the empty string is returned in that case.
464 ;__x*__ : Abbreviates ''x-$''.
465 ;__x-__ : Abbreviates ''x-$'' like __x*__, but omits the last word.
466
467
468
469
470 If a word designator is supplied without an event specification, the previous command is used as the event.
471
472 !Modifiers
473
474
475 After the optional word designator, there may appear a sequence of one or more of the following modifiers, each preceded by a `:'.
476
477
478 ;__h__ : Remove a trailing file name component, leaving only the head.
479 ;__t__ : Remove all leading file name components, leaving the tail.
480 ;__r__ : Remove a trailing suffix of the form ''.xxx'', leaving the basename.
481 ;__e__ : Remove all but the trailing suffix.
482 ;__p__ : Print the new command but do not execute it.
483 ;__q__ : Quote the substituted words, escaping further substitutions.
484 ;__x__ : Quote the substituted words as with __q__ , but break into words at __blanks__ and newlines.
485 ;__s/''old''/''new''/__ : Substitute ''new'' for the first occurrence of ''old'' in the event line. Any delimiter can be used in place of /. The final delimiter is optional if it is the last character of the event line. The delimiter may be quoted in ''old'' and ''new'' with a single backslash. If & appears in ''new'' , it is replaced by ''old'' . A single backslash will quote the &. If ''old'' is null, it is set to the last ''old'' substituted, or, if no previous history substitutions took place, the last ''string'' in a __!?''string''__[[?]____ search.
486 ;__&__ : Repeat the previous substitution.
487 ;__g__ : Cause changes to be applied over the entire event line. This is used in conjunction with `__:s__' (e.g., `__:gs/''old''__/''new''/') or `__:&__'. If used with `__:s__', any delimiter can be used in place of /, and the final delimiter is optional if it is the last character of the event line.
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