how to format a shell command line from a list of arguments in python

Question

I have a list of arguments, e.g. ["hello", "bobbity bob", "bye"]. How would I format these so they would be passed appropriately to a shell?

Wrong:

>>> " ".join(args)
hello bobbity bob bye

Correct:

>>> magic(args)
hello "bobbity bob" bye

Answer 1

You could use the undocumented but long-stable (at least since Oct 2004) subprocess.list2cmdline:

In [26]: import subprocess
In [34]: args=["hello", "bobbity bob", "bye"]

In [36]: subprocess.list2cmdline(args)
Out[36]: 'hello "bobbity bob" bye'

Answer 2

The easier way to solve your problem is to add \"...\" whenever your text has at least two words.
So to do that :

# Update the list
for str in args:
  if len(str.split(" ")) > 2:
    # Update the element within the list by
    # Adding at the beginning and at the end \"

    ...

# Print args
" ".join(args)