Python Command line execution

Question

I am trying to rename a set of pdf files in my desktop using a simple python script. I am somehow not very successful. My current code is :

import os,subprocess
path = "/Users/armed/Desktop/"
for file in os.listdir(path)
 command = ['mv', '*.pdf' , 'test.pdf'] // mv Command to rename files to test.pdf
 subprocess.call(command)

The output i get for this code is 1 and the files are not renamed. The same command works when executed in the terminal. I am using a Mac (if that helps in any way)

• Keith: How many PDF files are in that directory? That shell command should fail if there is more than one.
• Amritha: Your right. There was only one pdf at the time when I was trying out the command. but realized that renaming will fail for more than one and started trying out moving all the pdfs to another directory.

Answer 1

The same command works when executed in the terminal.

Except it's not the same command. The code is running:

'mv' '*.pdf' 'test.pdf'

but when you type it out it runs:

'mv' *.pdf 'test.pdf'

The difference is that the shell globs the * wildcard before executing mv. You can simulate what it does by using the glob module.

• Amritha: Thanks for the fast reply ! So am I supposed to make this code work by using the glob module ? i looked up the documentation but dont quite understand it. do I need to specify glob.glob(*.pdf) within the subprocess call ?
• Ignacio Vazquez-Abrams: glob.glob() returns a list. You must integrate it into the list you pass to subprocess.call().

Answer 2

Python is not going to expand the shell wildcard in the string by default. You can also do this without a subprocess. But your code will lose all pdf files except the last one.

from glob import glob
import os
path = "/Users/armed/Desktop/"
os.chdir(path)
for filename in glob("*.pdf"):
 os.rename(filename, "test.pdf")

But I'm sure that's not what you really want. You'll need a better destination name.

• Amritha: I am actually looking for ways to execute command line instructions through python. Thanks anyway !