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<title>execline: the fdblock program</title>
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<h1> The <tt>fdblock</tt> program </h1>
<p>
<tt>fdblock</tt> sets or unsets the O_NONBLOCK flag on a given file descriptor
(which makes reading or writing non-blocking or blocking), then executes
a program.
</p>
<h2> Interface </h2>
<pre>
fdblock [ -n ] <em>fd</em> <em>prog...</em>
</pre>
<p>
<tt>fdblock</tt> makes the file descriptor number <em>fd</em> blocking,
no matter what its previous state was. It then execs into <em>prog</em>
with its arguments.
</p>
<h2> Options </h2>
<ul>
<li> <tt>-n</tt> : non-blocking. Sets <em>fd</em> to non-blocking
mode instead of blocking mode. If used on stdin (0) or stdout (1), this
option will make a lot of command-line programs behave improperly, because
most simple command-line programs only support blocking stdin and stdout.
Make sure you know what you are doing. </li>
</ul>
<h2> Notes </h2>
<ul>
<li> <tt>fdblock</tt> has no portable shell equivalent. </li>
</ul>
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