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<title>execline: the ifte command</title>
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<p>
<a href="index.html">execline</a><br />
<a href="//skarnet.org/software/">Software</a><br />
<a href="//skarnet.org/">skarnet.org</a>
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<h1> The <tt>ifte</tt> program </h1>
<p>
<tt>ifte</tt> performs a conditional alternative.
</p>
<h2> Interface </h2>
<p>
In an <a href="execlineb.html">execlineb</a> script:
</p>
<pre>
ifte [ -X ] [ -n ] { <em>progthen...</em> } { <em>progelse...</em> } <em>progif...</em>
</pre>
<ul>
<li> <tt>ifte</tt> reads <em>progthen...</em> and <em>progelse...</em> in two
consecutive <a href="el_semicolon.html">blocks</a>. </li>
<li> <tt>ifte</tt> runs <em>progif...</em> as a child process
and waits for it to complete. </li>
<li> If <em>progif...</em> crashes (i.e. is killed by a signal), <tt>ifte</tt>
prints an error message, then exits 128 plus the number of the signal that
killed <em>progif</em>. </li>
<li> If <em>progif...</em> exits zero, <tt>ifte</tt> execs into
<em>progthen...</em>, else it execs into <em>progelse...</em>. </li>
</ul>
<h2> Options </h2>
<ul>
<li> <tt>-X</tt> : do not exit if <em>progif</em> crashes; instead,
proceed as if the test had returned false. </li>
<li> <tt>-n</tt> : negate the test. <em>progthen...</em> will be run
iff <em>progif...</em> exits nonzero. </li>
</ul>
<h2> Notes </h2>
<p>
<tt>ifte</tt> is a simpler version of <a href="ifthenelse.html">ifthenelse</a>.
It performs <em>only</em> conditional execution, not instruction sequence.
</p>
<p>
"<tt>ifthenelse { progif } { progthen } { progelse } remainder</tt>" is the
equivalent of "<tt>; { ifte { progthen } { progelse } progif } remainder</tt>".
</p>
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