subprocess - Python: Executing a shell command

Question

I need to do this:

paste file1 file2 file3 > result

I have the following in my python script:

from subprocess import call

// other code here.

// Here is how I call the shell command

call ["paste", "file1", "file2", "file3", ">", "result"])

Unfortunately I get this error:

paste: >: No such file or directory.

Any help with this will be great!

Answer 1

You need to implement the redirection yourself, if you're wisely deciding not to use a shell.

The docs at https://docs.python.org/2/library/subprocess.html warn you not to use a pipe -- but, you don't need to:

import subprocess
with open('result', 'w') as out:
    subprocess.call(["paste", "file1", "file2", "file3"], stdout=out)

should be just fine.