Little helper for shell commands from python

commander-tests.py

import unittest

from commander import *

class TestCommander(unittest.TestCase):
	
	def test_run(self):
		r = run("ping", "localhost")
		self.assertIsNone(r)
	
	def test_try_run(self):
		r = try_run("ping", "localhost")
		self.assertEqual(r, 0)
		
	def test_try_run__bad_command(self):
		r = try_run("ping", "--bad-option")
		self.assertNotEqual(r, 0)
		
	def test_run2(self):
		out = run2("ping", "localhost")
		self.assertTrue(out.strip().lower().startswith("pinging"))
		
	def test_try_run2(self):
		(r,out) = try_run2("ping", "localhost")
		self.assertEqual(r, 0)
		self.assertTrue(out.strip().lower().startswith("pinging"))
		
	def test_try_run2__bad_command(self):
		(r,_) = try_run2("ping", "--bad-option")
		self.assertNotEqual(r, 0)
		
	def test_cd(self):
		pass
	
if __name__ == "__main__":
	unittest.main()

commander.py

#!/usr/bin/python3
"""
A collection of functions to run shell commands from python.

These functions are just simple wrappers to subprocess.run 
but this interface favors convention over configuration for simple use cases

https://en.wikipedia.org/wiki/Convention_over_configuration
"""

import os
import subprocess

# "private" module functions

def _run(*args, shell=False, cwd=None):
	subprocess.run(args, stdout=subprocess.DEVNULL, shell=shell, cwd=cwd, check=True)
	
def _try_run(*args, shell=False, cwd=None):
	completedProcess = subprocess.run(args, stdout=subprocess.DEVNULL, shell=shell, cwd=cwd)
	return completedProcess.returncode

def _run2(*args, shell=False, cwd=None):
	completedProcess = subprocess.run(args, stdout=subprocess.PIPE, universal_newlines=True, shell=shell, cwd=cwd, check=True)
	return completedProcess.stdout
	
def _try_run2(*args, shell=False, cwd=None):
	completedProcess = subprocess.run(args, stdout=subprocess.PIPE, universal_newlines=True, shell=shell, cwd=cwd)
	return (completedProcess.returncode,completedProcess.stdout)
	
class _Cwd:
	def __init__(self, directory='.', shell=False):
		self.directory = directory
		self.shell = shell
		
	def run(self, *args): 
		return _run(*args, shell=self.shell, cwd=self.directory)
	
	def try_run(self, *args): 
		return _try_run(*args, shell=self.shell, cwd=self.directory)
	
	def run2(self, *args): 
		return _run2(*args, shell=self.shell, cwd=self.directory)
	
	def try_run2(self, *args): 
		return _try_run2(*args, shell=self.shell, cwd=self.directory)
		
	def cd(self, directory):
		normpath = os.path.normpath( os.path.join(self.directory, directory) )
		return _Cwd(directory=normpath, shell=self.shell)	
	
	def shell(self):
		return _Cwd(directory=self.directory, shell=True)
		
# public module functions
		
def run(*args):
	"""
	Run a command on the system.
	
	ex: run("git","commit","-m","hello commit")
	
	Fails if the command returns a non-zero exit status
	""" 
	return _run(*args)
	
def try_run(*args):
	"""
	Try to run a command on the system. Returns the exit status.
	
	ex: 
		
	exit_status = try_run("git","commit","-m","hello commit")
	
	if exit_status == 0:
		# success
	else:
		# failure
	""" 
	return _try_run(*args)

def run2(*args):
	"""
	Run a command on the system. Returns the output as a string
	
	ex: 
		
	msg = run2("echo", "hello")
	print(msg, "world") # hello world
	
	Fails if the command returns a non-zero exit status
	""" 
	return _run2(*args)

def try_run2(*args): 
	"""
	Try to run a command on the system. Returns the exit status and ouput in a tuple
	
	ex: 
		
	(exit_status,msg) = try_run2("echo", "hello")
	
	if exit_status == 0:
		# success
		print(msg, "world") # hello world
	else:
		# failure
		...
	""" 
	return _try_run2(*args)
	
def cd(directory):
	"""
	Returns an object with commander functions run, try_run, run2, try_run2, cd, shell
	where the commands run with directory as the cwd
	
	ex:
		
	cmdA = cd("A") # commands run from directory A
	dirAContents = cmdA.run2("ls")
	
	cmdAB = cmd.cd("B") # commands run from directory A/B
	dirBContents = cmdAB.run("ls")
	""" 
	return _Cwd(directory=directory)
	
def shell():
	"""
	Returns an object with commander functions run, try_run, run2, try_run2, cd, shell
	where the commands run in a shell
	
	ex:
	
	cmd = shell(True)
	johndoe_password = cmd.run2("cat /etc/passwd | grep johndoe")
	""" 
	return _Cwd(shell=True)