Executing Interactive shell script in python

Question

I have a shell script with ask for the user input. Consider a below example

Test.sh

#!/bin/bash
echo -n "Enter name > "
read text
echo "You entered: $text"
echo -n "Enter age > "
read text
echo "You entered: $text"
echo -n "Enter location > "
read text
echo "You entered: $text"

Script Execution:

sh test.sh
Enter name> abc
You entered: abc
Enter age > 35
You entered: 35
Enter location > prop
You entered: prop

Now i called this script in python program. I am doing this using sub process module. As far as i know sub process module creates a new process. The problem is when i execute the python script i am not able to pass the parameters to underlying shell script and the scipt is in hault stage. Could some point me where i am doing wrong

python script (CHECK.PY):

import subprocess, shlex


cmd = "sh test.sh"
proc = subprocess.Popen(shlex.split(cmd), stdout=subprocess.PIPE, stderr=subprocess.PIPE)
stdout,stderr = proc.communicate()

print stdout

Python Execution: check.py

 python check.py

We can perform the same thing using OS module, But i am trying to achieve using subprocess module — Fla-Hyd
– Fla-Hyd, Commented Oct 5, 2016 at 11:05

Moinuddin Quadri · Accepted Answer · 2016-10-05 11:22:55Z

7

Your code is working, but since you mention stdout=subprocess.PIPE the content is going to stdout variable you defined in stdout,stderr = proc.communicate(). Remove stdout=subprocess.PIPE argument from your Popen() call and you will see the output.

Alternatively, you should be using subprocess.check_call() as:

subprocess.check_call(shlex.split(cmd))

edited Oct 5, 2016 at 11:22

answered Oct 5, 2016 at 11:07

Moinuddin Quadri

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4 Comments

Fla-Hyd Over a year ago

Thanks for the answer. How can we capture the output of that script? I am having python 2.6.6

Moinuddin Quadri Over a year ago

If you will capture the output, you would not be able to see the content of printed by your script on the console. Is that what you want? For that you may use subprocess.check_output()

Fla-Hyd Over a year ago

Check_output works fine.. I tested.. But i need to use python 2.6.6

instinct246 Over a year ago

Thanks for the answer - is there a way to make this work in Jupyter. It works fine in command line but not on Jupyter!

mhawke · Accepted Answer · 2016-10-05 11:15:41Z

2

Actually the subprocess does work - but you are not seeing the prompts because the standard out of the child process is being captured by proc.communicate(). You can confirm this by entering values for the 3 prompts and you should finally see the prompts and your input echoed.

Just remove the stdout=subprocess.PIPE (same for stderr) and the subprocess' stdout (stderr) will go to the terminal.

Or there are other functions that will start a subprocess and call communicate() for you, such as subprocess.call() or subprocess.check_call()

answered Oct 5, 2016 at 11:15

mhawke

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