mingw/info/gdb/Readline-Init-File-Syntax.html

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  12 Node:<a name="Readline%20Init%20File%20Syntax">Readline Init File Syntax</a>,
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  17
  18 <h4 class="subsection">Readline Init File Syntax</h4>
  19
  20    <p>There are only a few basic constructs allowed in the
  21 Readline init file.  Blank lines are ignored.
  22 Lines beginning with a <code>#</code> are comments.
  23 Lines beginning with a <code>$</code> indicate conditional
  24 constructs (see <a href="Conditional-Init-Constructs.html#Conditional%20Init%20Constructs">Conditional Init Constructs</a>).  Other lines
  25 denote variable settings and key bindings.
  26
  27      <dl>
  28 <dt>Variable Settings
  29      <dd>You can modify the run-time behavior of Readline by
  30 altering the values of variables in Readline
  31 using the <code>set</code> command within the init file.
  32 The syntax is simple:
  33
  34      <pre class="example">          set <var>variable</var> <var>value</var>
  35           </pre>
  36
  37      <p>Here, for example, is how to
  38 change from the default Emacs-like key binding to use
  39 <code>vi</code> line editing commands:
  40
  41      <pre class="example">          set editing-mode vi
  42           </pre>
  43
  44      <p>Variable names and values, where appropriate, are recognized without regard
  45 to case.
  46
  47      <p>A great deal of run-time behavior is changeable with the following
  48 variables.
  49
  50           <dl>
  51
  52           <br><dt><code>bell-style</code>
  53           <dd>Controls what happens when Readline wants to ring the terminal bell.
  54 If set to <code>none</code>, Readline never rings the bell.  If set to
  55 <code>visible</code>, Readline uses a visible bell if one is available.
  56 If set to <code>audible</code> (the default), Readline attempts to ring
  57 the terminal's bell.
  58
  59           <br><dt><code>comment-begin</code>
  60           <dd>The string to insert at the beginning of the line when the
  61 <code>insert-comment</code> command is executed.  The default value
  62 is <code>"#"</code>.
  63
  64           <br><dt><code>completion-ignore-case</code>
  65           <dd>If set to <code>on</code>, Readline performs filename matching and completion
  66 in a case-insensitive fashion.
  67 The default value is <code>off</code>.
  68
  69           <br><dt><code>completion-query-items</code>
  70           <dd>The number of possible completions that determines when the user is
  71 asked whether he wants to see the list of possibilities.  If the
  72 number of possible completions is greater than this value,
  73 Readline will ask the user whether or not he wishes to view
  74 them; otherwise, they are simply listed.
  75 This variable must be set to an integer value greater than or equal to 0.
  76 The default limit is <code>100</code>.
  77
  78           <br><dt><code>convert-meta</code>
  79           <dd>If set to <code>on</code>, Readline will convert characters with the
  80 eighth bit set to an <small>ASCII</small> key sequence by stripping the eighth
  81 bit and prefixing an &lt;ESC&gt; character, converting them to a
  82 meta-prefixed key sequence.  The default value is <code>on</code>.
  83
  84           <br><dt><code>disable-completion</code>
  85           <dd>If set to <code>On</code>, Readline will inhibit word completion.
  86 Completion  characters will be inserted into the line as if they had
  87 been mapped to <code>self-insert</code>.  The default is <code>off</code>.
  88
  89           <br><dt><code>editing-mode</code>
  90           <dd>The <code>editing-mode</code> variable controls which default set of
  91 key bindings is used.  By default, Readline starts up in Emacs editing
  92 mode, where the keystrokes are most similar to Emacs.  This variable can be
  93 set to either <code>emacs</code> or <code>vi</code>.
  94
  95           <br><dt><code>enable-keypad</code>
  96           <dd>When set to <code>on</code>, Readline will try to enable the application
  97 keypad when it is called.  Some systems need this to enable the
  98 arrow keys.  The default is <code>off</code>.
  99
 100           <br><dt><code>expand-tilde</code>
 101           <dd>If set to <code>on</code>, tilde expansion is performed when Readline
 102 attempts word completion.  The default is <code>off</code>.
 103
 104           <br><dt><code>horizontal-scroll-mode</code>
 105           <dd>This variable can be set to either <code>on</code> or <code>off</code>.  Setting it
 106 to <code>on</code> means that the text of the lines being edited will scroll
 107 horizontally on a single screen line when they are longer than the width
 108 of the screen, instead of wrapping onto a new screen line.  By default,
 109 this variable is set to <code>off</code>.
 110
 111           <br><dt><code>input-meta</code>
 112           <dd>If set to <code>on</code>, Readline will enable eight-bit input (it
 113 will not clear the eighth bit in the characters it reads),
 114 regardless of what the terminal claims it can support.  The
 115 default value is <code>off</code>.  The name <code>meta-flag</code> is a
 116 synonym for this variable.
 117
 118           <br><dt><code>isearch-terminators</code>
 119           <dd>The string of characters that should terminate an incremental search without
 120 subsequently executing the character as a command (see <a href="Searching.html#Searching">Searching</a>).
 121 If this variable has not been given a value, the characters &lt;ESC&gt; and
 122 <kbd>C-J</kbd> will terminate an incremental search.
 123
 124           <br><dt><code>keymap</code>
 125           <dd>Sets Readline's idea of the current keymap for key binding commands.
 126 Acceptable <code>keymap</code> names are
 127 <code>emacs</code>,
 128 <code>emacs-standard</code>,
 129 <code>emacs-meta</code>,
 130 <code>emacs-ctlx</code>,
 131 <code>vi</code>,
 132 <code>vi-move</code>,
 133 <code>vi-command</code>, and
 134 <code>vi-insert</code>.
 135 <code>vi</code> is equivalent to <code>vi-command</code>; <code>emacs</code> is
 136 equivalent to <code>emacs-standard</code>.  The default value is <code>emacs</code>.
 137 The value of the <code>editing-mode</code> variable also affects the
 138 default keymap.
 139
 140           <br><dt><code>mark-directories</code>
 141           <dd>If set to <code>on</code>, completed directory names have a slash
 142 appended.  The default is <code>on</code>.
 143
 144           <br><dt><code>mark-modified-lines</code>
 145           <dd>This variable, when set to <code>on</code>, causes Readline to display an
 146 asterisk (<code>*</code>) at the start of history lines which have been modified.
 147 This variable is <code>off</code> by default.
 148
 149           <br><dt><code>output-meta</code>
 150           <dd>If set to <code>on</code>, Readline will display characters with the
 151 eighth bit set directly rather than as a meta-prefixed escape
 152 sequence.  The default is <code>off</code>.
 153
 154           <br><dt><code>print-completions-horizontally</code>
 155           <dd>If set to <code>on</code>, Readline will display completions with matches
 156 sorted horizontally in alphabetical order, rather than down the screen.
 157 The default is <code>off</code>.
 158
 159           <br><dt><code>show-all-if-ambiguous</code>
 160           <dd>This alters the default behavior of the completion functions.  If
 161 set to <code>on</code>,
 162 words which have more than one possible completion cause the
 163 matches to be listed immediately instead of ringing the bell.
 164 The default value is <code>off</code>.
 165
 166           <br><dt><code>visible-stats</code>
 167           <dd>If set to <code>on</code>, a character denoting a file's type
 168 is appended to the filename when listing possible
 169 completions.  The default is <code>off</code>.
 170
 171      </dl>
 172
 173      <br><dt>Key Bindings
 174      <dd>The syntax for controlling key bindings in the init file is
 175 simple.  First you need to find the name of the command that you
 176 want to change.  The following sections contain tables of the command
 177 name, the default keybinding, if any, and a short description of what
 178 the command does.
 179
 180      <p>Once you know the name of the command, simply place on a line
 181 in the init file the name of the key
 182 you wish to bind the command to, a colon, and then the name of the
 183 command.  The name of the key
 184 can be expressed in different ways, depending on what you find most
 185 comfortable.
 186
 187      <p>In addition to command names, readline allows keys to be bound
 188 to a string that is inserted when the key is pressed (a <var>macro</var>).
 189
 190           <dl>
 191 <dt><var>keyname</var>:&nbsp;<var>function-name</var>&nbsp;or&nbsp;<var>macro</var>
 192           <dd><var>keyname</var> is the name of a key spelled out in English.  For example:
 193           <pre class="example">               Control-u: universal-argument
 194                Meta-Rubout: backward-kill-word
 195                Control-o: "&gt; output"
 196                </pre>
 197
 198           <p>In the above example, <kbd>C-u</kbd> is bound to the function
 199 <code>universal-argument</code>,
 200 <kbd>M-DEL</kbd> is bound to the function <code>backward-kill-word</code>, and
 201 <kbd>C-o</kbd> is bound to run the macro
 202 expressed on the right hand side (that is, to insert the text
 203 <code>&gt; output</code> into the line).
 204
 205           <p>A number of symbolic character names are recognized while
 206 processing this key binding syntax:
 207 <var>DEL</var>,
 208 <var>ESC</var>,
 209 <var>ESCAPE</var>,
 210 <var>LFD</var>,
 211 <var>NEWLINE</var>,
 212 <var>RET</var>,
 213 <var>RETURN</var>,
 214 <var>RUBOUT</var>,
 215 <var>SPACE</var>,
 216 <var>SPC</var>,
 217 and
 218 <var>TAB</var>.
 219
 220           <br><dt>"<var>keyseq</var>":&nbsp;<var>function-name</var>&nbsp;or&nbsp;<var>macro</var>
 221           <dd><var>keyseq</var> differs from <var>keyname</var> above in that strings
 222 denoting an entire key sequence can be specified, by placing
 223 the key sequence in double quotes.  Some <small>GNU</small> Emacs style key
 224 escapes can be used, as in the following example, but the
 225 special character names are not recognized.
 226
 227           <pre class="example">               "\C-u": universal-argument
 228                "\C-x\C-r": re-read-init-file
 229                "\e[11~": "Function Key 1"
 230                </pre>
 231
 232           <p>In the above example, <kbd>C-u</kbd> is again bound to the function
 233 <code>universal-argument</code> (just as it was in the first example),
 234 <code></code><kbd>C-x</kbd><code> </code><kbd>C-r</kbd><code></code> is bound to the function <code>re-read-init-file</code>,
 235 and <code>&lt;ESC&gt; &lt;[&gt; &lt;1&gt; &lt;1&gt; &lt;~&gt;</code> is bound to insert
 236 the text <code>Function Key 1</code>.
 237
 238      </dl>
 239
 240      <p>The following <small>GNU</small> Emacs style escape sequences are available when
 241 specifying key sequences:
 242
 243           <dl>
 244 <dt><code></code><kbd>\C-</kbd><code></code>
 245           <dd>control prefix
 246 <br><dt><code></code><kbd>\M-</kbd><code></code>
 247           <dd>meta prefix
 248 <br><dt><code></code><kbd>\e</kbd><code></code>
 249           <dd>an escape character
 250 <br><dt><code></code><kbd>\\</kbd><code></code>
 251           <dd>backslash
 252 <br><dt><code></code><kbd>\"</kbd><code></code>
 253           <dd>&lt;"&gt;, a double quotation mark
 254 <br><dt><code></code><kbd>\'</kbd><code></code>
 255           <dd>&lt;'&gt;, a single quote or apostrophe
 256 </dl>
 257
 258      <p>In addition to the <small>GNU</small> Emacs style escape sequences, a second
 259 set of backslash escapes is available:
 260
 261           <dl>
 262 <dt><code>\a</code>
 263           <dd>alert (bell)
 264 <br><dt><code>\b</code>
 265           <dd>backspace
 266 <br><dt><code>\d</code>
 267           <dd>delete
 268 <br><dt><code>\f</code>
 269           <dd>form feed
 270 <br><dt><code>\n</code>
 271           <dd>newline
 272 <br><dt><code>\r</code>
 273           <dd>carriage return
 274 <br><dt><code>\t</code>
 275           <dd>horizontal tab
 276 <br><dt><code>\v</code>
 277           <dd>vertical tab
 278 <br><dt><code>\</code><var>nnn</var><code></code>
 279           <dd>the character whose <small>ASCII</small> code is the octal value <var>nnn</var>
 280 (one to three digits)
 281 <br><dt><code>\x</code><var>nnn</var><code></code>
 282           <dd>the character whose <small>ASCII</small> code is the hexadecimal value <var>nnn</var>
 283 (one to three digits)
 284 </dl>
 285
 286      <p>When entering the text of a macro, single or double quotes must
 287 be used to indicate a macro definition.
 288 Unquoted text is assumed to be a function name.
 289 In the macro body, the backslash escapes described above are expanded.
 290 Backslash will quote any other character in the macro text,
 291 including <code>"</code> and <code>'</code>.
 292 For example, the following binding will make <code></code><kbd>C-x</kbd><code> \</code>
 293 insert a single <code>\</code> into the line:
 294      <pre class="example">          "\C-x\\": "\\"
 295           </pre>
 296
 297    </dl>
 298
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