Python function for running a shell command

run.py

def run(command_str, ignore_errors=False, **kwargs):
    """
    Run the given command and return the output.  Any keyword arguments provided
    will be formatted into the command string.  Quoting arguments should not be
    necessary.

    Example:
        run('rm {file}', file='test file')
            => rm "test file"

        run('rm "test file"')
            => same as previous, but you may have to worry more about escaping

        run('ping -c {count} {host}', host='www.google.com', count=4)
            => ping -c 4 www.google.com

    If ignore_errors is False (the default) then an exception will be raised if
    the exit code of the command is non-zero.

    If you want a literal '{' to appear in the command, use '{{' instead.
    Same for '}'
    """
    command_parts = shlex.split(command_str)
    for index, part in enumerate(command_parts):
        command_parts[index] = part.format(**kwargs)

    try:
        return subprocess.check_output(command_parts)
    except subprocess.CalledProcessError:
        if ignore_errors:
            return None
        else:
            raise