title: GCC directory option -isystem
body: <p>From this link: <a href="http://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html">http://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html</a></p>
  
  <blockquote>
    <p>If a standard system include
    directory, or a directory specified
    with -isystem, is also specified with
    -I, the -I option will be ignored. The directory will still be searched but
    as a system directory at its normal
    position in the system include chain.</p>
  </blockquote>
  
  <p>What is the way to run this?</p>
  
  <pre><code>[14:45:37 Wed Apr 27] ~/junkPrograms/src  $gcc hello.c -isystem -I ../include/
  ../include/: file not recognized: Is a directory
  collect2: ld returned 1 exit status
  [14:45:42 Wed Apr 27] ~/junkPrograms/src  $gcc hello.c -I isystem ../include/
  ../include/: file not recognized: Is a directory
  collect2: ld returned 1 exit status
  [14:45:57 Wed Apr 27] ~/junkPrograms/src  $
  </code></pre>
  
  <p>and does this mean that if <em>-isystem</em> is attached, the dir will be given the precedence of a normal system dir?</p>