#!/usr/local/bin/python

# Reverse order of lines in specified file
import sys

def usage(): # Print usage help to console
	"""Print usage help to console."""
	print "Usage:", sys.argv[0], "{file to reverse}"
	sys.exit()

try:
	f = open(sys.argv[1], 'r+')
except IOError, IndexError:
	print "Error: Cannot open file", sys.argv[1]
	usage()
else:
	text = f.readlines()
	text.reverse()
	f.seek(0)
	f.writelines(text)
	f.close