Python script for compressing files in batches (WITH CHECK)

from time import sleep
import os
from subprocess import Popen, PIPE
path=r"/storeM/fat/screenshots/active/"
archiveFilename = r'/storeM/fat/screenshots/7z/test3.7z'
#ensure path string ends in '/'
if path[len(path)-1] != '/':
    path = path + r'/'

dirList=os.listdir(path)

maxStackSize = 20
splitBatches = {}
batchStack = 0
currentStack = []
currentStackNumber = 0

#let's make some batches of a given size (ignore anything greater for now)
for file in dirList:
    if batchStack < maxStackSize:
        batchStack = batchStack + 1
        currentStack.append(path + file)
    else:
        batchStack = 0
        splitBatches[currentStackNumber]=currentStack
        currentStack = []
        currentStackNumber = currentStackNumber + 1


def checkCommand(cmd):
    p = Popen(cmd, stdout=PIPE, shell=True)
    p.wait()
    result = p.communicate()[0]
    assert 'Everything is Ok' in result

for batch in splitBatches:
    batchOfFilenames = str(splitBatches[batch]).replace(',','').replace("'",'').replace('"','').replace('[','').replace(']','')
    #print batchOfFilenames
    checkCommand(r'7za a '+ archiveFilename +r' '+ batchOfFilenames)
    os.system('rm '+ batchOfFilenames)