Compares two text files and outputs the differing lines (like diff without the extra stuff)

package_list_diff.py

#!/usr/bin/env python

from sys import argv,exit

def list_strip(list):
	new_list = []
	for line in list:
		if not line.strip():
			continue
		else:
			new_list.append(line.strip())
	return new_list

def read_file_to_list(filename):
	try:
		file = open(filename, 'r')
		list = file.readlines()
		file.close()
		return list_strip(list)
	except IOError:
		print "Error: %s does not exist." % filename
		exit()

def main():
	try:
		l1 = read_file_to_list(argv[1])
		l2 = read_file_to_list(argv[2])
		diff = list(set(l1) - set(l2))
		print ' '.join(sorted(diff)).strip()
	except IndexError:
		print 'Please specify two input files.'
		exit()

if __name__ == "__main__":
	exit(main())