Execute shell command in Perl-like manner.

cmd.py

import sys
import os
from subprocess import CalledProcessError, check_output

def cmd(cmd_arg):
    """Execute shell command in Perl-like manner."""
    ctx = globals().copy()
    ctx.update(sys._getframe(1).f_locals)
    for ln in check_output(cmd_arg.format(**ctx), shell=True).split(os.linesep):
        yield ln
    
filelist = '*.txt'
pattern = 'xyz'
for ln in cmd('dir {pattern} {filelist}'):
    print ln