Python Running Bash Script and Getting Output

Question

I need to run a bash script and get the output. The script has a loop with avariable.

It works on terminal screen when I paste bash script only, but it gives error when I use subprocess by using Python. Here is the code:

import subprocess

text1 = """
declare -a StringArray=("a1" "a2" "a3" "a4" "a5" )
for val in ${StringArray[@]}; do
   echo $val
done
"""
text_output = (subprocess.check_output(text1, shell=True).strip()).decode()

This is the error:

/bin/sh: 2: Syntax error: "(" unexpected
Traceback (most recent call last):
.
.
.
' returned non-zero exit status 2.

What is the solution?

Python3.7, OS: Debian-like Linux, Kernel: 4.19.

maij · Accepted Answer · 2021-04-23 17:51:18Z

1

The error message states: /bin/sh .... Python does not use bash as you expect. It uses another shell. (On my system sh is dash.) And it seems that this other shell does not support the StringArray=("a1" "a2" "a3" "a4" "a5" ) syntax.

You can try to explicitly select bash like this:

subprocess.check_output(text1, shell=True, executable='/bin/bash')

(At least, /bin/bash works on my system.)

edited Apr 23, 2021 at 17:51

answered Apr 19, 2021 at 11:51

maij

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Comments

Vikash Kumar · Accepted Answer · 2021-04-19 10:59:21Z

0

You can use subprocess.Popen in this case.

Below is the code that can help you achieve the above. Please let me know if you have any question.

>>> import subprocess
>>> cmd = 'declare -a StringArray=("a1" "a2" "a3" "a4" "a5" );for val in ${StringArray[@]}; do echo $val; done'
>>> x=subprocess.Popen(cmd,shell=True)
>>> a1
a2
a3
a4
a5

answered Apr 19, 2021 at 10:59

Vikash Kumar

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1 Comment

demirod Over a year ago

It did not work with /bin/sh: 1: Syntax error: "(" unexpected error.

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