cat.py

来自「《简明 Python 教程》为 "A Byte of Python" 的唯一指定」· Python 代码 · 共 40 行

#!/usr/bin/env 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)