sunshinekitty sunshinekitty - 1 month ago 10
Python Question

How to force os.system() to use bash instead of shell

I've tried what's told in How to force /bin/bash interpreter for oneliners

By doing

os.system('GREPDB="my command"')
os.system('/bin/bash -c \'$GREPDB\'')


However no luck, unfortunately I need to run this command with bash and subp isn't an option in this environment, I'm limited to python 2.4. Any suggestions to get me in the right direction?

Answer

Both commands are executed in different subshells.

Setting variables in the first system call does not affect the second system call.

You need to put two command in one string (combining them with ;).

>>> import os
>>> os.system('GREPDB="echo 123"; /bin/bash -c "$GREPDB"')
123
0

NOTE You need to use "$GREPDB" instead of '$GREPDBS'. Otherwise it is interpreted literally instead of being expanded.

If you can use subprocess:

>>> import subprocess
>>> subprocess.call('/bin/bash -c "$GREPDB"', shell=True,
...                 env={'GREPDB': 'echo 123'})
123
0