Call Python script from bash with argument

I know that I can run a python script from my bash script using the following:

python python_script.py 

But what about if I wanted to pass a variable / argument to my python script from my bash script. How can I do that?

Basically bash will work out a filename and then python will upload it, but I need to send the filename from bash to python when I call it.

8 Answers

To execute a python script in a bash script you need to call the same command that you would within a terminal. For instance

> python python_script.py var1 var2 

To access these variables within python you will need

import sys print(sys.argv[0]) # prints python_script.py print(sys.argv[1]) # prints var1 print(sys.argv[2]) # prints var2 

Beside sys.argv, also take a look at the argparse module, which helps define options and arguments for scripts.

The argparse module makes it easy to write user-friendly command-line interfaces.

Use

python python_script.py filename 

and in your Python script

import sys print sys.argv[1] 

Embedded option:

Wrap python code in a bash function.

#!/bin/bash function current_datetime { python - <<END import datetime print datetime.datetime.now() END } # Call it current_datetime # Call it and capture the output DT=$(current_datetime) echo Current date and time: $DT 

Use environment variables, to pass data into to your embedded python script.

#!/bin/bash function line { PYTHON_ARG="$1" python - <<END import os line_len = int(os.environ['PYTHON_ARG']) print '-' * line_len END } # Do it one way line 80 # Do it another way echo $(line 80) 

use in the script:

echo $(python python_script.py arg1 arg2) > /dev/null 

or

python python_script.py "string arg" > /dev/null 

The script will be executed without output.

I have a bash script that calls a small python routine to display a message window. As I need to use killall to stop the python script I can't use the above method as it would then mean running killall python which could take out other python programmes so I use

pythonprog.py "$argument" & # The & returns control straight to the bash script so must be outside the backticks. The preview of this message is showing it without "`" either side of the command for some reason.

As long as the python script will run from the cli by name rather than python pythonprog.py this works within the script. If you need more than one argument just use a space between each one within the quotes.

and take a look at the getopt module. It works quite good for me!

Print all args without the filename:

for i in range(1, len(sys.argv)): print(sys.argv[i])