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  • 使用sys,argv

    #!/usr/bin/python
    # Filename: cat.py


    import sys

    def readfile(filename):
        '''Print a file to the standard output.'''
        f = file(filename)
        while True:
            line = f.readline()

            if len(line) == 0:
                break
            print line, # notice comma
        f.close()

    # Script starts from here
    if len(sys.argv) < 2:
        print 'No action specified.'
        sys.exit()

    if sys.argv[1].startswith('--'):
        option = sys.argv[1][2:]
        # fetch sys.argv[1] but without the first two characters
        if option == 'version':
            print 'Version 1.2'
        elif option == 'help':
            print '''
    This program prints files to the standard output.
    Any number of files can be specified.
    Options include:
      --version : Prints the version number
      --help    : Display this help'''

        else:
            print 'Unknown option.'
        sys.exit()
    else:
        for filename in sys.argv[1:]:
            readfile(filename)

    输出

    $ python cat.py
    No action specified.

    $ python cat.py --help
    This program prints files to the standard output.
    Any number of files can be specified.
    Options include:
      --version : Prints the version number
      --help    : Display this help

    $ python cat.py --version
    Version 1.2

    $ python cat.py --nonsense
    Unknown option.

    $ python cat.py poem.txt
    Programming is fun
    When the work is done
    if you wanna make your work also fun:
            use Python!

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  • 原文地址:https://www.cnblogs.com/nku-wangfeng/p/7696700.html
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