Master process (SCM_USETMPDIR, SCM_TMPDIR, TMPDIR)

The master process will by default write to the directory in which it was started.

You can change this by setting the SCM_USETMPDIR environment variable to 'yes'. In that case, the master process will create a scratch directory just as the child processes do. Typically this is a good idea for performance reasons.

The master program will take care of copying required files from the startup directory to the scratch directory, and it will also copy the result files back to the startup directory. Thus you can use it as if it is running in the directory in which you start it.