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| <h4 class="subsection">31.3.2 Conditional Init Constructs</h4> |
| |
| <p>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. |
| |
| <dl> |
| <dt><code>$if</code><dd>The <code>$if</code> 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. |
| |
| <dl> |
| <dt><code>mode</code><dd>The <code>mode=</code> form of the <code>$if</code> directive is used to test |
| whether Readline is in <code>emacs</code> or <code>vi</code> mode. |
| This may be used in conjunction |
| with the ‘<samp><span class="samp">set keymap</span></samp>’ command, for instance, to set bindings in |
| the <code>emacs-standard</code> and <code>emacs-ctlx</code> keymaps only if |
| Readline is starting out in <code>emacs</code> mode. |
| |
| <br><dt><code>term</code><dd>The <code>term=</code> 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 |
| ‘<samp><span class="samp">=</span></samp>’ is tested against both the full name of the terminal and |
| the portion of the terminal name before the first ‘<samp><span class="samp">-</span></samp>’. This |
| allows <code>sun</code> to match both <code>sun</code> and <code>sun-cmd</code>, |
| for instance. |
| |
| <br><dt><code>application</code><dd>The <var>application</var> construct is used to include |
| application-specific settings. Each program using the Readline |
| library sets the <var>application name</var>, and you 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: |
| <pre class="example"> $if Bash |
| # Quote the current or previous word |
| "\C-xq": "\eb\"\ef\"" |
| $endif |
| </pre> |
| </dl> |
| |
| <br><dt><code>$endif</code><dd>This command, as seen in the previous example, terminates an |
| <code>$if</code> command. |
| |
| <br><dt><code>$else</code><dd>Commands in this branch of the <code>$if</code> directive are executed if |
| the test fails. |
| |
| <br><dt><code>$include</code><dd>This directive takes a single filename as an argument and reads commands |
| and bindings from that file. |
| For example, the following directive reads from <samp><span class="file">/etc/inputrc</span></samp>: |
| <pre class="example"> $include /etc/inputrc |
| </pre> |
| </dl> |
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