Python argv用法详解
想用python处理一下文件，发现有argv这个用法，搜来学习一下。
如果想对python脚步传参数，那么就需要命令行参数的支持了，这样可以省的每次去改脚步了。
用法是：python xx.py xxx
举例如下：
#-*- coding:utf- -*- from sys import argv script,first = argv print "the script is called:", script print "the first variable is:", first
结果如下
这里argv接收到的是一个列表变量
#-*- coding:utf- -*- from sys import argv f = open(argv[], 'r') print f.read() f.close()
比方说这里我读取文件名，开始写成了 open(argv, 'r')，会提示类型错误，改成argv[1]就好了
下面再来详细介绍下sys.argv[]用法
Sys.argv[]是用来获取命令行参数的，sys.argv[0]表示代码本身文件路径，所以参数从1开始，以下两个例子说明：
1、使用sys.argv[]的一简单实例，
import sys,os os.system(sys.argv[1])
这个例子os.system接收命令行参数，运行参数指令，保存为sample1.py，命令行带参数运行sample1.py notepad，将打开记事本程序。
2、这个例子是简明python教程上的，明白它之后你就明白sys.argv[]了。
import sys
def readfile(filename): #从文件中读出文件内容
'''''Print a file to the standard output.'''
f = file(filename)
while True:
line = f.readline()
if len(line) == 0:
break
print line, # notice comma 分别输出每行内容
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': #当命令行参数为-- version，显示版本号
print 'Version 1.2'
elif option == 'help': #当命令行参数为--help时，显示相关帮助内容
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:]: #当参数为文件名时，传入readfile，读出其内容
readfile(filename) 保存程序为sample.py.我们验证一下：
1) 命令行带参数运行：sample.py –version 输出结果为：version 1.2
2) 命令行带参数运行：sample.py –help 输出结果为：This program prints files……
3) 在与sample.py同一目录下，新建a.txt的记事本文件，内容为：test argv；命令行带参数运行：sample.py a.txt，输出结果为a.txt文件内容：test argv，这里也可以多带几个参数，程序会先后输出参数文件内容。
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