call shell command from python

Question

I have this shell command that I want to call from python

frontend='test'
instance_list = subprocess.call(['sudo gcloud compute instances list | grep -v TERMINA | grep +'frontend'+ | awk '{ print $1 }''])

I'm getting this error

    instance_list = subprocess.call(['sudo gcloud compute instances list | grep -v TERMINA | grep +'frontend'+ | awk '{ print $1 }''])
                                                                                                           ^
SyntaxError: invalid syntax

What I'm doing wrong?

Drop the `+` concatenation (old syntax) and use [string formatting](https://www.w3schools.com/python/ref_string_format.asp). — S3DEV, Jul 09 '20 at 11:04
Does this answer your question? [Calling an external command from Python](https://stackoverflow.com/questions/89228/calling-an-external-command-from-python) — Roshin Raphel, Jul 09 '20 at 11:05

score 1 · Accepted Answer · answered Jul 09 '20 at 10:58

1

How about this:

frontend='test'
instance_list = subprocess.call(['sudo gcloud compute instances list | grep -v TERMINA | grep '+frontend+' | awk \'{ print $1 }\''])

You just did the string concatenation wrong: the plus needs to be outside of the quotes... And the quotes for awk probably need to be escaped...

answered Jul 09 '20 at 10:58

ynotzort

156
5

okay now I'm getting error in this awk '{ print $1 }'']) ^ SyntaxError: invalid syntax – Jack Jul 09 '20 at 11:00
see my edit: probably you need to escape the quotes around awk (\' instead of ') – ynotzort Jul 09 '20 at 11:01

score 0 · Answer 2 · answered Jul 09 '20 at 10:58

0

You should put the plus signs outside the quotation marks:

instance_list = subprocess.call(['sudo gcloud compute instances list | grep -v TERMINA | grep '+frontend+' | awk '{ print $1 }''])

answered Jul 09 '20 at 10:58

Baraa

176
7

score 0 · Answer 3 · answered Jul 09 '20 at 11:03

I Think the problem is in the way you arranged your quotations and concatenation sign (+)

Concatenation works like: 'Hello' + variable + 'world'

Or when it is about escaping quotes inside (Which is probably not your case) You can use triple quotes like xxx.call([''' You are free to use single quotes inside here ''']);

For your case, this can help:

instance_list = subprocess.call(['sudo gcloud compute instances list | grep -v TERMINA | grep ' + frontend + ' | awk '{ print $1 }''])

call shell command from python

3 Answers3