Execute shell command or print text in Perl-like manner.

cmdfmt.py

import sys
import os
from subprocess import CalledProcessError, check_output

def cmd(cmd_arg, local_only=False):
    """Execute shell command in Perl-like manner."""
    if local_only:
        ctx = sys._getframe(1).f_locals
    else:
        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
        
def fmt(spec):
    """Format string with caller's variable scope."""
    return spec.format(**sys._getframe(1).f_locals)

def fmt2(spec):
    """Format string with caller's variable scope and global scope."""
    ctx = globals().copy()
    ctx.update(sys._getframe(1).f_locals)
    return spec.format(**ctx)