You can use the env command--either in a PBS script or on the command line of a PBS interactive session--to find out what environment variables are set within a PBS job. In addition to the PBS_X environment variables, the following variables are useful to know:
- NCPUS
- Defaults to number of CPUs that you requested for the node.
- OMP_NUM_THREADS
- Defaults to 1 unless you explicitly set it to a different number. If your PBS job runs an OpenMP or MPI/OpenMP application, this variable sets the number of threads in the parallel region.
- FORT_BUFFERED
- Defaults to 1. Setting this variable to 1 enables records to be accumulated in the buffer and flushed to disk later.