How to use export with Python on Linux

Question

I need to make an export like this in Python :

# export MY_DATA=\"my_export\"

I\'ve tried to do :

# -*- python-mode -*-
# -         


        

Answer 1

Not that simple:

python -c "import os; os.putenv('MY_DATA','1233')"
$ echo $MY_DATA # <- empty

But:

python -c "import os; os.putenv('MY_DATA','123'); os.system('bash')"
$ echo $MY_DATA #<- 123

Answer 2

You actually want to do

import os
os.environ["MY_DATA"] = "my_export"

Answer 3

Another way to do this, if you're in a hurry and don't mind the hacky-aftertaste, is to execute the output of the python script in your bash environment and print out the commands to execute setting the environment in python. Not ideal but it can get the job done in a pinch. It's not very portable across shells, so YMMV.

$(python -c 'print "export MY_DATA=my_export"')

(you can also enclose the statement in backticks in some shells ``)

Answer 4

export is a command that you give directly to the shell (e.g. bash), to tell it to add or modify one of its environment variables. You can't change your shell's environment from a child process (such as Python), it's just not possible.

Here's what's happening when you try os.system('export MY_DATA="my_export"')...

/bin/bash process, command `python yourscript.py` forks python subprocess
 |_
   /usr/bin/python process, command `os.system()` forks /bin/sh subprocess
    |_
      /bin/sh process, command `export ...` changes its local environment

When the bottom-most /bin/sh subprocess finishes running your export ... command, then it's discarded, along with the environment that you have just changed.

Answer 5

Kind of a hack because it's not really python doing anything special here, but if you run the export command in the same sub-shell, you will probably get the result you want.

import os

cmd = "export MY_DATA='1234'; echo $MY_DATA" # or whatever command
os.system(cmd)

Answer 6

import os
import shlex
from subprocess import Popen, PIPE


os.environ.update(key=value)

res = Popen(shlex.split("cmd xxx -xxx"), stdin=PIPE, stdout=PIPE, stderr=PIPE,
            env=os.environ, shell=True).communicate('y\ny\ny\n'.encode('utf8'))
stdout = res[0]
stderr = res[1]