title: Checking if errno != EINTR: what does it mean?
body: <p>I've found this piece of code used several times (also a similar one where it's used <code>open()</code> instead of <code>write()</code>).</p>
  
  <pre><code>int c = write(fd, &amp;v, sizeof(v));
  if (c == -1 &amp;&amp; errno != EINTR) {
      perror("Write to output file");
      exit(EXIT_FAILURE);
  }
  </code></pre>
  
  <p><strong>Why it is checked if <code>&amp;&amp; errno != EINTR</code> here ?</strong></p>
  
  <p>Looking for <code>errno</code> on <em>man</em> I found the following text about <code>EINTR</code>, but even if I visited <code>man 7 signal</code> that doesn't enlighten me.</p>
  
  <blockquote>
    <p>EINTR Interrupted function call (POSIX.1); see signal(7).</p>
  </blockquote>