Search code examples
pythonpython-2.7string-formatting

How to pass a variable into a bash command in Python

I have a Python script which selects a port at random and passes it to the bash command:

#!/usr/bin/env python
import random
import os

# Select a port at random
port = ['22', '23', '24']
selected_port = (random.choice(port))
# print 'selected_port

bashCommand = "ssh -p '${selected_port}' -i pi.rsa pi@192.168.1.xx"
os.system(bashCommand)

What is the correct way to pass selected_port variable to my bashCommand? Currently I'm getting a SyntaxError: EOL while scanning string literal

Solution

  • Use one of Python's string interpolation mechanisms:

    bashCommand = "ssh -p '%s' -i pi.rsa pi@192.168.1.xx" % selected_port

    or

    bashCommand = "ssh -p '{}' -i pi.rsa pi@192.168.1.xx".format(selected_port)