python习题:去除文件中的重复行

去除文件中的重复行，前提：文件已经经过排序

#!/usr/bin/env python

#去除重复行

import sys
import os

def printUsage():
    print("Usage: python uniq.py sourcefile ")

def printFileNotExist():
    print(":( Sorry, File " , sys.argv[1], " does not exist!")

def uniqFile(filename):
    fp = open(filename,"r")
    preline = '';
    for line in fp:
        line.strip()
        if line == preline:
            continue
        print(line,end="")
        preline = line    
    
if __name__ == "__main__":
    if len(sys.argv) != 2:
        printUsage()
        exit()

    if not os.path.isfile(sys.argv[1]):
        printFileNotExist()
        exit()

    uniqFile(sys.argv[1])