Question

I am trying to source a bash script containing some environment variables in python. I followed one other thread to do it. But, there seems that one of the variable is malformed, as can be seen in the given snippet.

COLORTERM=gnome-terminal
mc=() {  . /usr/share/mc/mc-wrapper.sh
}
_=/usr/bin/env

I am using the following code to set up the current environment.

import os
import pprint
import subprocess

command = ['bash', '-c', 'source init_env && env']

proc = subprocess.Popen(command, stdout = subprocess.PIPE)

for line in proc.stdout:
    (key, _, value) = line.partition("=")
    os.environ[key] = value

proc.communicate()

‘

If I change the above code a little like putting a condition:

for line in proc.stdout:
    (key, _, value) = line.partition("=")
    if not value:
        continue
    os.environ[key] = value

then things are working but the environment is corrupted because of one missing bracket as can be seen from the snippet of environment variable that the bracket is appearing on new line. Because of this corruption, If I run some other command like

os.system("ls -l")

it gives me the following error

sh: mc: line 1: syntax error: unexpected end of file
sh: error importing function definition for `mc'

What could be the possible solutions for this problem?

Thanks alot

Answer 1

Probably the best way to do this is to create a separate program that writes out the environment variables in a way that is easily and unambiguously processed by your own program; then call that program instead of env. Using the standard pickle module, that separate program can be as simple as this:

import os
import sys
import pickle

pickle.dump(os.environ, sys.stdout)

which you can either save into its own .py file, or else put directly in a Bash command:

python -c 'import os, sys, pickle; pickle.dump(os.environ, sys.stdout)'

In either case, you can process its output like this:

import os
import pprint
import subprocess
import pickle

command = [
      'bash',
      '-c',
      'source init_env && ' +
         'python -c "import os, sys, pickle; ' +
                    'pickle.dump(os.environ, sys.stdout)"'
]

proc = subprocess.Popen(command, stdout = subprocess.PIPE)

for k, v in pickle.load(proc.stdout).iteritems():
    os.environ[k] = v

proc.communicate()