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<h3 class="section">13.5 Dangers of Mixing Streams and Descriptors</h3>

<p><a name="index-channels-1242"></a><a name="index-streams-and-descriptors-1243"></a><a name="index-descriptors-and-streams-1244"></a><a name="index-mixing-descriptors-and-streams-1245"></a>
You can have multiple file descriptors and streams (let's call both
streams and descriptors &ldquo;channels&rdquo; for short) connected to the same
file, but you must take care to avoid confusion between channels.  There
are two cases to consider: <dfn>linked</dfn> channels that share a single
file position value, and <dfn>independent</dfn> channels that have their own
file positions.

   <p>It's best to use just one channel in your program for actual data
transfer to any given file, except when all the access is for input. 
For example, if you open a pipe (something you can only do at the file
descriptor level), either do all I/O with the descriptor, or construct a
stream from the descriptor with <code>fdopen</code> and then do all I/O with
the stream.

<ul class="menu">
<li><a accesskey="1" href="Linked-Channels.html#Linked-Channels">Linked Channels</a>: 	   Dealing with channels sharing a file position. 
<li><a accesskey="2" href="Independent-Channels.html#Independent-Channels">Independent Channels</a>:    Dealing with separately opened, unlinked channels. 
<li><a accesskey="3" href="Cleaning-Streams.html#Cleaning-Streams">Cleaning Streams</a>: 	   Cleaning a stream makes it safe to use
                            another channel. 
</ul>

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