Subprocess callout for python

shell.py

import shlex
from subprocess import Popen, PIPE

def is_stringy(x):
    '''
    Is x a multiple type (like list, dict, tuple), or a 'single' type,
    such as string.   
    
    >>> is_stringy(xrange(3))
    False
    >>> is_stringy(u'blah')
    True
    '''
    return not hasattr(x,"__iter__")


def shell(args_or_command, input='',**kwargs):
    ''' uses subprocess pipes to call out to the shell.
    
    Args:
        args_or_command:  args to the command, or command string
        input:  what should go to stdin of the process
        kwargs:  goes to Popen, see help(subprocess.Popen) for a list.
    
    Returns:
        stdout, stderr
        
    >>> shell('basename /a/hello')
    ('hello\n','')
    '''
    if is_stringy(args_or_command):
        args = shlex.split(args_or_command)
    else:
        args = args_or_command
    
    stdout = kwargs.pop('stdout',PIPE)
    stderr = kwargs.pop('stderr',PIPE)
    p = Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE,**kwargs)
    stdout, stderr = p.communicate(input=input)
    return stdout, stderr