sys-系統(tǒng)特定的參數(shù)和功能
該模塊提供對(duì)解釋器使用或維護(hù)的一些變量的訪問,以及與解釋器強(qiáng)烈交互的函數(shù)。它始終可用。
代碼如下
#!/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)