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<a name="Conditional-Init-Constructs"></a>
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<p>
Next: <a href="Sample-Init-File.html#Sample-Init-File" accesskey="n" rel="next">Sample Init File</a>, Previous: <a href="Readline-Init-File-Syntax.html#Readline-Init-File-Syntax" accesskey="p" rel="previous">Readline Init File Syntax</a>, Up: <a href="Readline-Init-File.html#Readline-Init-File" accesskey="u" rel="up">Readline Init File</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Conditional-Init-Constructs-1"></a>
<h4 class="subsection">32.3.2 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.
</p>
<dl compact="compact">
<dt><code>$if</code></dt>
<dd><p>The <code>$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, after any comparison operator,
extends to the end of the line;
unless otherwise noted, no characters are required to isolate it.
</p>
<dl compact="compact">
<dt><code>mode</code></dt>
<dd><p>The <code>mode=</code> form of the <code>$if</code> directive is used to test
whether Readline is in <code>emacs</code> or <code>vi</code> mode.
This may be used in conjunction
with the &lsquo;<samp>set keymap</samp>&rsquo; command, for instance, to set bindings in
the <code>emacs-standard</code> and <code>emacs-ctlx</code> keymaps only if
Readline is starting out in <code>emacs</code> mode.
</p>
</dd>
<dt><code>term</code></dt>
<dd><p>The <code>term=</code> form may be used to include terminal-specific
key bindings, perhaps to bind the key sequences output by the
terminal&rsquo;s function keys.  The word on the right side of the
&lsquo;<samp>=</samp>&rsquo; is tested against both the full name of the terminal and
the portion of the terminal name before the first &lsquo;<samp>-</samp>&rsquo;.  This
allows <code>sun</code> to match both <code>sun</code> and <code>sun-cmd</code>,
for instance.
</p>
</dd>
<dt><code>version</code></dt>
<dd><p>The <code>version</code> test may be used to perform comparisons against
specific Readline versions.
The <code>version</code> expands to the current Readline version.
The set of comparison operators includes
&lsquo;<samp>=</samp>&rsquo; (and &lsquo;<samp>==</samp>&rsquo;), &lsquo;<samp>!=</samp>&rsquo;, &lsquo;<samp>&lt;=</samp>&rsquo;, &lsquo;<samp>&gt;=</samp>&rsquo;, &lsquo;<samp>&lt;</samp>&rsquo;,
and &lsquo;<samp>&gt;</samp>&rsquo;.
The version number supplied on the right side of the operator consists
of a major version number, an optional decimal point, and an optional
minor version (e.g., &lsquo;<samp>7.1</samp>&rsquo;). If the minor version is omitted, it
is assumed to be &lsquo;<samp>0</samp>&rsquo;.
The operator may be separated from the string <code>version</code> and
from the version number argument by whitespace.
The following example sets a variable if the Readline version being used
is 7.0 or newer:
</p><div class="example">
<pre class="example">$if version &gt;= 7.0
set show-mode-in-prompt on
$endif
</pre></div>

</dd>
<dt><code>application</code></dt>
<dd><p>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:
</p><div class="example">
<pre class="example">$if Bash
# Quote the current or previous word
&quot;\C-xq&quot;: &quot;\eb\&quot;\ef\&quot;&quot;
$endif
</pre></div>

</dd>
<dt><code>variable</code></dt>
<dd><p>The <var>variable</var> construct provides simple equality tests for Readline
variables and values.
The permitted comparison operators are &lsquo;<samp>=</samp>&rsquo;, &lsquo;<samp>==</samp>&rsquo;, and &lsquo;<samp>!=</samp>&rsquo;.
The variable name must be separated from the comparison operator by
whitespace; the operator may be separated from the value on the right hand
side by whitespace.
Both string and boolean variables may be tested. Boolean variables must be
tested against the values <var>on</var> and <var>off</var>.
The following example is equivalent to the <code>mode=emacs</code> test described
above:
</p><div class="example">
<pre class="example">$if editing-mode == emacs
set show-mode-in-prompt on
$endif
</pre></div>
</dd>
</dl>

</dd>
<dt><code>$endif</code></dt>
<dd><p>This command, as seen in the previous example, terminates an
<code>$if</code> command.
</p>
</dd>
<dt><code>$else</code></dt>
<dd><p>Commands in this branch of the <code>$if</code> directive are executed if
the test fails.
</p>
</dd>
<dt><code>$include</code></dt>
<dd><p>This directive takes a single filename as an argument and reads commands
and bindings from that file.
For example, the following directive reads from <samp>/etc/inputrc</samp>:
</p><div class="example">
<pre class="example">$include /etc/inputrc
</pre></div>
</dd>
</dl>

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Next: <a href="Sample-Init-File.html#Sample-Init-File" accesskey="n" rel="next">Sample Init File</a>, Previous: <a href="Readline-Init-File-Syntax.html#Readline-Init-File-Syntax" accesskey="p" rel="previous">Readline Init File Syntax</a>, Up: <a href="Readline-Init-File.html#Readline-Init-File" accesskey="u" rel="up">Readline Init File</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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