How to pass a variable into a bash command in Python

Question

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

`bashCommand = "ssh -p '{}' -i pi.rsa pi@192.168.1.xx".format(selected_port)` — Anubis, Apr 20 '19 at 09:39
Form the command string properly bashCommand = "ssh -p " + selected_port + " -i pi.rsa pi@192.168.1.xx" — Paula Livingstone, Apr 20 '19 at 09:42
Possible duplicate of [String formatting in Python](https://stackoverflow.com/questions/517355/string-formatting-in-python) — Anubis, Apr 20 '19 at 09:46
@PaulaLivingstone though above works in given specific scenario, it's not generating the identical string as single quotes are missing. — Anubis, Apr 20 '19 at 09:47

score 0 · Accepted Answer · answered Apr 20 '19 at 09:38

0

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)

answered Apr 20 '19 at 09:38

Thomas

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How to pass a variable into a bash command in Python

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