Run `command` through the shell and return a tuple of the return code and the output.

shell.py

from subprocess import PIPE, Popen, STDOUT

class ShellError(Exception):
   def __init__(self, command, returnCode, output):
      self.command = command
      self.returnCode = returnCode
      self.output = output

   def __str__(self):
      return '''Command '%s' exited with non-zero exit code %s.
      Output:
      %s ''' % (self.command, self.returnCode, self.output)

def shell(command, expectedReturnCode=0):
   r'''
   Run `command` through the shell and return a tuple of the return code
   and the output.

   >>> shell('uname -s')   
   (0, 'Linux\n')

   >>> shell('ld -f')
   Traceback (most recent call last):
      ...
   ShellError: Command 'ld -f' exited with non-zero exit code 1.
         Output:
         ld: unrecognized option '-f'
   ld: use the --help option for usage information
   <BLANKLINE>

   >>> shell('ld -f', 1)
   (1, "ld: unrecognized option '-f'\nld: use the --help option for usage information\n")
   '''
   p = Popen(command, shell=True, stdout=PIPE, stderr=STDOUT)
   output = p.communicate()[0]
   if p.returncode != expectedReturnCode:
      raise ShellError(command, p.returncode, output)
   return (p.returncode, output)