title: TEMP_FAILURE_RETRY and __USE_GNU
body: <p>I'm on Ubuntu 10.04 using GCC and I want to use the macro TEMP_FAILURE_RETRY as described here:</p>
  
  <p><a href="http://www.gnu.org/s/hello/manual/libc/Interrupted-Primitives.html" rel="noreferrer">http://www.gnu.org/s/hello/manual/libc/Interrupted-Primitives.html</a></p>
  
  <p>However, when I compile I got the following error:</p>
  
  <pre><code>undefined reference to `TEMP_FAILURE_RETRY'
  </code></pre>
  
  <p>I looked in unistd.h where the macro is defined and it is preceded by:</p>
  
  <pre><code>#ifdef __USE_GNU
  </code></pre>
  
  <p>How do I get my code to compile and use this macro?   Can I simply wrap it using the same #ifdef __USE_GNU in my code?</p>