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sys-系统特定的参数和功能
该模块提供对解释器使用或维护的一些变量的访问,以及与解释器强烈交互的函数。它始终可用。
代码如下
#!/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)