Is it possible to set an environment variable from Python permanently?

Question

Using os module I can get the values of the environment variables. For example:

os.environ['HOME']

However, I cannot set the environment variables:

os.environ['BLA'] = "FOO"

It works in the current session of the program but when I python program is finished, I do not see that it changed (or set) values of the environment variables. Is there a way to do it from Python?

Answer 1

If what you want is to make your environment variables persist accross sessions, you could

For unix

do what we do when in bash shell. Append you environment variables inside the ~/.bashrc .

import os
with open(os.path.expanduser("~/.bashrc"), "a") as outfile:
    # 'a' stands for "append"  
    outfile.write("export MYVAR=MYVALUE")

or for Windows :

setx /M MYVAR "MYVALUE"

in a *.bat that is in Startup in Program Files

Answer 2

if you want to do it and set them up forever into a user account you can use setx but if you want as global you can use setx /M but for that you might need elevation, (i am using windows as example, (for linux you can use export )

import subprocess
if os.name == 'posix':  # if is in linux
    exp = 'export hi2="youAsWell"'
if os.name == 'nt':  # if is in windows
    exp = 'setx hi2 "youAsWell"'
subprocess.Popen(exp, shell=True).wait()

after running that you can go to the environments and see how they been added into my user environments

Answer 3

@rantanplan's answer is correct. For Unix however, if you wish to set multiple environment variables i suggest you add a \\n at the end of outfile line as following:

outfile.write("export MYVAR=MYVALUE\n")

So the code looks like the following:

import os
with open(os.path.expanduser("~/.bashrc"), "a") as outfile:
    # 'a' stands for "append"  
    outfile.write("export MYVAR1=MYVALUE1\n")
    outfile.write("export MYVAR2=MYVALUE2\n")

This will prevent appending "export" word at the end of the value of the environment variable.

Answer 4

I am not sure. You can return the variable and set it that way. To do this print it.

(python program)

...
print foo

(bash)

set -- $(python test.py)
foo=$1

Answer 5

you can use py-setenv to do that job. It will access windows registry and do a change for you, install via python -m pip install py-setenv