# b4run function¶

When using the Fortran code, the command:

make output


invokes the runclaw function from $CLAW/clawutil/src/python/clawutil/runclaw.py to run the Fortran executable. Starting in v5.7.1, this function has been modified to look for a Python b4run function to be executed before running the Fortran code. This can be used, for example, to: • automate copying certain files into the _output directory (e.g. you might want to keep the Makefile and setrun.py that were used for the run along with the output), • generate a log file with more information about the run, e.g. what time the run was started and what directory the input files came from (the rundir). The file$CLAW/clawutil/src/python/clawutil/b4run.py is a sample file showing the format it should have, and implements the sample actions described above.

To search for a b4run.py file, the current rundir directory is first checked and if there is no such file in this directory then the environment variable B4RUN is checked, which can be set to the full path of a b4run.py file that you wish to use globally, for example.