Python - Convert string to command

Question

I'm currently creating a script that'll loop run a set of Subprocess, and then wait for all the subprocess to finish. I have to add variables in to the subprocess before running them, so I was thinking of writing it as a string, and then converting the string to a command? Would something like that exist?

For example, I have these stringss:

"p1 = subprocess.Popen('python','hello.py')"
"p2 = subprocess.Popen('python','hello2.py')"

How would I execute it to be able to call p1 or p2 later on in the script? (E.g p1.wait())

Since you're running Python files, you could consider using the multiprocessing module instead if it suits you. — Asclepius
– Asclepius, Commented Sep 5, 2013 at 17:49

Ashwini Chaudhary · Accepted Answer · 2013-09-05 17:45:55Z

6

Using strings is a bad idea, I'd use a list:

options = [('python','hello.py'), ('python','hello2.py')]
for option in options:
    process = subprocess.Popen(option) 
    #do something here

edited Sep 5, 2013 at 17:45

answered Sep 5, 2013 at 16:58

Ashwini Chaudhary

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2 Comments

Robᵩ Over a year ago

You probably want to save the result of subprocess.Popen: processes = [subprocess.Popen(option) for option in options]

jcfollower Over a year ago

If 'python' is always used, you don't need to keep repeating it in the list.

Magnus Grindal Bakken · Accepted Answer · 2013-09-05 16:57:44Z

0

exec("p1 = subprocess.Popen('python','hello.py')")

Note that exec executes statements, while eval evaulates expressions.

But I agree with the other answer that it's better to do this in a different way if you can. One thing you should definitely never do is execute arbitrary strings whose source you don't know, for instance if they could come from a user.

answered Sep 5, 2013 at 16:57

Magnus Grindal Bakken

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1 Comment

l4mpi Over a year ago

... also note that execing random strings is a very bad practice.

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