I have a script that looks something like this:
export foo=/tmp/foo export bar=/tmp/bar
Every time I build I run 'source init_env' (where init_env is the above script) to set up some variables.
To accomplish the same in Python I had this code running,
reg = re.compile('export (?P<name>\w+)(\=(?P<value>.+))*') for line in open(file): m = reg.match(line) if m: name = m.group('name') value = '' if m.group('value'): value = m.group('value') os.putenv(name, value)
But then someone decided it would be nice to add a line like the following to the
Obviously my Python script fell apart. I could modify the Python script to handle this line, but then it'll just break later on when someone comes up with a new feature to use in the
The question is if there is an easy way to run a Bash command and let it modify my
The problem with your approach is that you are trying to interpret bash scripts. First you just try to interpret the export statement. Then you notice people are using variable expansion. Later people will put conditionals in their files, or process substitutions. In the end you will have a full blown bash script interpreter with a gazillion bugs. Don't do that.
Let Bash interpret the file for you and then collect the results.
You can do it like this:
#! /usr/bin/env python import os import pprint import shlex import subprocess command = shlex.split("env -i 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() pprint.pprint(dict(os.environ))
Make sure that you handle errors in case bash fails to
source init_env, or bash itself fails to execute, or subprocess fails to execute bash, or any other errors.
env -i at the beginning of the command line creates a clean environment. that means you will only get the environment variables from
init_env. if you want the inherited system environment then omit
Read the documentation on subprocess for more details.
Note: this will only capture variables set with the
export statement, as
env only prints exported variables.
Note that the Python documentation says that if you want to manipulate the environment you should manipulate
os.environ directly instead of using
os.putenv(). I consider that a bug, but I digress.
import os, pickle # For clarity, I moved this string out of the command source = 'source init_env' dump = '/usr/bin/python -c "import os,pickle;print pickle.dumps(os.environ)"' penv = os.popen('%s && %s' %(source,dump)) env = pickle.loads(penv.read()) os.environ = env
This uses json, subprocess, and explicitly uses /bin/bash (for ubuntu support):
import os, subprocess as sp, json source = 'source init_env' dump = '/usr/bin/python -c "import os, json;print json.dumps(dict(os.environ))"' pipe = sp.Popen(['/bin/bash', '-c', '%s && %s' %(source,dump)], stdout=sp.PIPE) env = json.loads(pipe.stdout.read()) os.environ = env