title: OpenMP Programming : How to specify the number of threads as a command line option
body: <p>I am running a local <a href="http://blast.ncbi.nlm.nih.gov/Blast.cgi" rel="noreferrer">blastx</a> server.  One of the command line options is -num_threads.  Looking at the executable, blastx, thinking it may be a shell script that sets OMP_NUM_THREADS, it turns out that it is in machine code. I am assuming (possibly incorrectly) that it is an OpenMP application and this got me thinking.</p>
  
  <p>Question : is it possible to change the number of OpenMP threads as a command line option, as opposed to using the environmental variable OMP_NUM_THREADS?</p>