import os
from subprocess import check_output

DEVNULL = open(os.devnull, "w")

x = check_output("module load gromacs; mdrun_avx -h", shell=True, stderr=DEVNULL)

a_file = open("deleteme", "w")

x = check_output("module load gromacs; mdrun_avx -h", shell=True, stderr=a_file)