How to set environment variables in Python?

Question

I need to set some environment variables in the Python script and I want all the other scripts that are called from Python to see the environment variables' set.

If I do,

os.environ["DEBUSSY"] = 1 

it complains saying that 1 has to be a string.

I also want to know how to read the environment variables in Python (in the latter part of the script) once I set it.

Answer 1

Environment variables must be strings, so use

os.environ["DEBUSSY"] = "1" 

to set the variable DEBUSSY to the string 1.

To access this variable later, simply use:

print(os.environ["DEBUSSY"]) 

Child processes automatically inherit the environment variables of the parent process -- no special action on your part is required.

Answer 2

You may need to consider some further aspects for code robustness;

when you're storing an integer-valued variable as an environment variable, try

os.environ['DEBUSSY'] = str(myintvariable) 

then for retrieval, consider that to avoid errors, you should try

os.environ.get('DEBUSSY', 'Not Set') 

possibly substitute '-1' for 'Not Set'

so, to put that all together

myintvariable = 1 os.environ['DEBUSSY'] = str(myintvariable) strauss = int(os.environ.get('STRAUSS', '-1')) # NB KeyError <=> strauss = os.environ['STRAUSS'] debussy = int(os.environ.get('DEBUSSY', '-1'))  print "%s %u, %s %u" % ('Strauss', strauss, 'Debussy', debussy)