passing double quotes in subprocess

Chris Angelico rosuav at gmail.com
Tue Sep 8 13:13:32 CEST 2015


On Tue, Sep 8, 2015 at 9:03 PM, loial <jldunn2000 at gmail.com> wrote:
> I need to execute an external shell script via subprocess on Linux.
>
> One of the parameters needs to be passed inside double quotes
>
> But the double quotes do not appear to be passed to the script
>
> I am using :
>
> myscript = '/home/john/myscript'
> commandline = myscript + ' ' + '\"Hello\"'
>
> process = subprocess.Popen(commandline, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
> output,err = process.communicate()
>
>
> if I make the call from another shell script and escape the double quotes it works fine, but not when I use python and subprocess.
>
> I have googled this but cannot find a solution...is there one?

First off: Can you remove the shell=True and provide the command as a
list, so it doesn't need to be parsed? If you can, that would be MUCH
better.

But if you can't, the simple fix is to use a raw string literal for
your Hello. The backslashes are getting lost:

>>> print('\"Hello\"')
"Hello"
>>> print(r'\"Hello\"')
\"Hello\"

If In Doubt, Print It Out. It's amazing how much you can learn with a
few well-placed print() calls :)

ChrisA


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