Python command-line arguments

Python command-line arguments

Python providesgetopt module to get command line arguments.

$ python test.py arg1 arg2 arg3

Python can also be used inthe sys sys.argvto get command line arguments:

• sys.argv is a list of command line parameters.

• len (sys.argv) is the number of command-line arguments.

NOTE: sys.argv [0] indicates the name of the script.

Examples

test.py file code is as follows:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import sys

print '参数个数为:', len(sys.argv), '个参数。'
print '参数列表:', str(sys.argv)

Implementation of the above code, the output is:

$ python test.py arg1 arg2 arg3
参数个数为: 4 个参数。
参数列表: ['test.py', 'arg1', 'arg2', 'arg3']

getopt module

getopt module is dedicated processing module command line parameters used to obtain command-line options and parameters, is sys.argv. Command-line option makes the program more flexible parameters. Support short option mode (-) and long options mode (-).

The module provides two methods and an exception handler to parse the command line arguments.

getopt.getopt method

getopt.getopt methods for parsing command-line parameter list syntax is as follows:

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

Method parameters:

• args: To parse the command-line argument list.

• options: to define the format string, the colon optionsafter (:) indicates that this option must have the additional parameters, without the colon indicates that this option is not additional parameters.

• long_options: define the format of the list,long_options after the equal sign (=) said that if this option is set, there must be additional parameters, or not additional parameters.

• This method returns a value consists of two elements: the first is the(option, value) tuples.The second is a list of parameters, including those that do not '-' or '-' parameter.

Another method is getopt.gnu_getopt, not much to do here described.

Exception getopt.GetoptError

Is not found in the list of parameters, or options desired parameter triggers the exception is empty.

Exception argument is a string that represents the error. Error message related options andopt for the msgattribute.

Examples

Suppose we create such a script, you can pass two lines to the script file filename command, while we use another option to view the script. Use the following script:

usage: test.py -i <inputfile> -o <outputfile>

test.py file code is as follows:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import sys, getopt

def main(argv):
   inputfile = ''
   outputfile = ''
   try:
      opts, args = getopt.getopt(argv,"hi:o:",["ifile=","ofile="])
   except getopt.GetoptError:
      print 'test.py -i <inputfile> -o <outputfile>'
      sys.exit(2)
   for opt, arg in opts:
      if opt == '-h':
         print 'test.py -i <inputfile> -o <outputfile>'
         sys.exit()
      elif opt in ("-i", "--ifile"):
         inputfile = arg
      elif opt in ("-o", "--ofile"):
         outputfile = arg
   print '输入的文件为：', inputfile
   print '输出的文件为：', outputfile

if __name__ == "__main__":
   main(sys.argv[1:])

Implementation of the above code, the output is:

$ python test.py -h
usage: test.py -i <inputfile> -o <outputfile>

$ python test.py -i inputfile -o outputfile
输入的文件为： inputfile
输出的文件为： outputfile