如何编写一个带命令行参数的Python文件

看到别人执行一个支持命令行参数的python文件，瞬间觉得高大上起来、牛逼起来，那么如何编写一个带命令行参数的python脚本呢？不用紧张，下面将简单易懂地让你学会如何让自己的python脚本，支持命令行参数。

首先你要知道python中的sys模块的一些功能：

import sys

print "the number of python program's argument:",len(sys.argv)

print "the value of every argument is ",str(sys.argv)

#上述程序的文件名sysargv.py
python sysargv.py argv1 argv2 argv3 argv4
the number of python program's argument: 5
the value of every argument is  ['sysargv.py', 'argv1', 'argv2', 'argv3', 'argv4']

其次，python程序使用命令行参数，必不可少的模块，就是getopt 模块,先看看一段代码

getopt.getopt(args, options[, long_options])

import getopt
args = '-a -b -cfoo -d bar a1 a2'.split()
args
['-a', '-b', '-cfoo', '-d', 'bar', 'a1', 'a2']
optlist, args = getopt.getopt(args, 'abc:d:')
optlist
[('-a', ''), ('-b', ''), ('-c', 'foo'), ('-d', 'bar')]
args
['a1', 'a2']

使用long_options

s = '--condition=foo --testing --output-file abc.def -x a1 a2'
args = s.split()
args
['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2']
optlist, args = getopt.getopt(args, 'x', ['condition=', 'output-file=', 'testing'])
optlist
[('--condition', 'foo'), ('--testing', ''), ('--output-file', 'abc.def'), ('-x', '')]
args
['a1', 'a2']

最后实战一个例子吧!

import getopt,sys

def main():
    try:
        opts,args=getopt.getopt(sys.argv[1:],"hi:o:v",["help","infile=","outfile="])
    except getopt.GetoptError as error:
        print str(error)
        usage()
        sys.exit(2)
    infile=None
    output=None
    verbose=False
    for key,value in opts:
        if key=="-v":
            verbose=True
        elif key in ("-h","--help"):
            print "sysargv.py -i <inputfile> -o <outputfile>"
            print "or sysargv.py --infile <inputfile> --outfile <outputfile>"

        elif key in ("-i","--infile"):
            infile = value
        elif key in ("-o","--outfile"):
            output= value
    print "inputfile:", infile
    print  "outputfile:", output
    print  verbose
if __name__=="__main__":
    main()

测试结果：

C:\Python27>python sysargv.py --help
sysargv.py -i <inputfile> -o <outputfile>
or sysargv.py --infile <inputfile> --outfile <outputfile>
inputfile: None
outputfile: None
False

C:\Python27>python sysargv.py -h
sysargv.py -i <inputfile> -o <outputfile>
or sysargv.py --infile <inputfile> --outfile <outputfile>
inputfile: None
outputfile: None
False

C:\Python27>python sysargv.py -i "inputfile1" -o "ouputfile2"
inputfile: inputfile1
outputfile: ouputfile2
False

C:\Python27>python sysargv.py -i "inputfile1"
inputfile: inputfile1
outputfile: None
False

C:\Python27>python sysargv.py -o "outputfile1"
inputfile: None
outputfile: outputfile1
False

C:\Python27>python sysargv.py -o "outputfile1" -v
inputfile: None
outputfile: outputfile1
True

C:\Python27>python sysargv.py --infile "inputfile" --outfile "outputfile1" -v
inputfile: inputfile
outputfile: outputfile1
True