Accessing shell variables in Python

Question

Running echo $HISTFILE in bash gives me /home/myname/.bash_history.

Now I'm trying to use Python to access this HISTFILE shell variable by doing the following:

import subprocess
x = subprocess.check_output('echo $HISTFILE', shell=True)
print(x)

However, this gives me a blank output.

1. If subprocess.check_output along with shell=True executes the command in a shell, why doesn't it have a HISTFILE variable that I can access?
2. How can I work my way around this?

• Olvin Roght: os.environ["HISTFILE"].
• Wander Nauta: Note that for HISTFILE to show up in the environment (os.environ), it must first be exported: unix.stackexchange.com/questions/295555 I think it isn't by default.
• Oli: $HISTFILE looks like any other environment variable but in reality it's a shell variable and you've to export it in order to access it using os.environ or child processes.

Answer 1

Using subprocess seems to be overkill for the task, you can use os.environ to access environment variables.

import os
os.environ['HISTFILE']

• magikarp: That gives me a KeyError.