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copied!<p>I think I can see several issues. I'll try to mention them in order of appearance.</p> <ul> <li>You should check <code>fork</code> for the return value <code>-1</code> which indicates an error (no child will have been forked in this case).</li> <li>All your calls to <code>fdopen</code> leak resources (depending on the implementation; the one on RHEL4 leaks). They return a <code>FILE*</code> which you could then use in <code>fwrite</code> etc. and then close by doing <code>fclose</code> on them. But you throw that value away. You don't need to open the pipe for reading/writing. Pipes are suitable for that when created.</li> <li>The child should close the ends of the pipe it does not use. Add <code>close (myin [1]); myin [1] = -1; close (myout [0]); myout [0] = -1; close (myerr [0]); myerr [0] = -1;</code></li> <li>The <code>dup2</code> are technically fine on all Linux variants I know, but it is customary to use the first fd of a pipe for reading and the other for writing. Thus, your <code>dup2</code>s would be best changed to <code>dup2 (myin [0], STDIN_FILENO); dup2 (myout [1], STDOUT_FILENO); dup2 (myerr [1], STDERR_FILENO);</code></li> <li>The parent should close the ends of the pipe it does not use. Add <code>close (myin [0]); myin [0] = -1; close (myout [1]); myout [1] = -1; close (myerr [1]); myerr [1] = -1;</code></li> <li><strong>Your main problem:</strong> You check the possibly uninitialized <code>status</code> for your child's exit code. But <code>waitpid</code> has not yet been called. You should check <code>waitpid</code>'s exit code and not evaluate <code>status</code> if it returns something other than <code>childpid</code>.</li> </ul> <h2>Edit</h2> <p>Since only the pipe ends that you actually need are open now, the operating system will detect a broken pipe for you. The pipe breaks when the child does <code>fclose (stdout)</code>. The parent can still proceed to read all the data that may be in the pipe, but after that <code>read</code> will return zero, indicating a broken pipe.</p> <p>Thus, you can actually spare the call to <code>waitpid</code>. You could instead simply wait for <code>read</code> to return zero. This is not 100% equivalent, though, since your child closes its end of the pipe before it goes to <code>sleep</code> (causing the parent to proceed when all data have been read), whereas the <code>waitpid</code> version, of course, only proceeds when the child actually died.</p>

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