tail.py

import sys
import linecache
import os

if os.path.isfile(sys.argv[1]):
   try:
       with open(sys.argv[1], 'r') as f:
           content = f.readlines()
       length = len(content)
   except IOError as e:
       print 'File does not exist'
   isFile = True
else:
    f = sys.stdin
    g = f.readlines()
    length = len(g)
    isFile = False

if isFile:
    if int(sys.argv[2]) >= 0:
       myArg = int(sys.argv[2])
    else:
       myArg = 5
    mark = length - myArg + 1
    for i in range(mark, length+1):
        sys.stdout.write(linecache.getline(sys.argv[1], i))
else:
    if int(sys.argv[1]) >= 0:
        myArg = int(sys.argv[1])
    else:
        myArg = 5
    mark = length - myArg
    for i in range(mark, length + 1):
        sys.stdout.write(g[i])