Python method Summary for getting command-line arguments

Describes how python obtains command-line arguments: getopt and Argparse modules.

Python version: 2.7

One, getopt module

The main use of the function in the module:

Options, args = Getopt.getopt (args, shortopts, longopts=[])

Parameter args: generally sys.argv[1:]. Filter out sys.argv[0], which is the name of the execution script, not the command line arguments.

Parameter shortopts: Short format parsing string. For example: "HP:I:", there is no colon after H, which means that there is no argument behind, p and I are followed by a colon, which indicates that the parameter is followed.

Parameter longopts: Long format parsing string list. For example: ["Help", "ip=", "port="],help, there is no equal sign behind it, no argument is followed, IP and port are followed by a colon, which means the parameters are followed.

Return values options are a list of tuples as elements, with each tuple in the form of: (option string, additional parameters), such as: ('-I ', ' 192.168.0.1 ')

The return value of args is a list of elements that do not contain '-' or '-' arguments.

Run the following command at the command line:

Python test_getopt.py-i 192.168.0.1-p 123 A

Or

Python test_getopt.py-ip=192.168.0.1--port=80 123 A

The test_getopt.py code is as follows:

#encoding =utf-8import getoptimport sysdef Main (argv):    try:        options, args = Getopt.getopt (argv, "hp:i:", ["Help "," ip= "," port= "])    except getopt. Getopterror:        sys.exit ()    for option, value in Options:        if option in ("-H", "--help"):            print ("Help")        if option in ("-I", "--ip"):            print ("IP is: {0}". Format (value))        if option in ("-P", "--port"):            print (" Port is: {0} ". Format (value)"    print ("error args: {0}". Format (args)) if __name__ = = ' __main__ ':    Main (sys.argv[ 1:])

The results of the operation are as follows:

Second, Argparse module

Standard module for parsing command-line options and parameters.

Steps to use:

1:import Argparse #导入模块

2:parser = Argparse. Argumentparser () #创建解析对象

3:parser.add_argument () #向该对象中添加使用到的命令行选项和参数

4:parser.parser_args () #解析命令行

Next, the following methods are described in detail Argumentparser and add_argument:

Argumentparser (Prog=none, Usage=none, Description=none, Epilog=none, parents=[], Formatter_class=argparser. Helpformatter, prefix_chars= '-', Fromfile_prefix_chars=none, Argument_default=none, conflict_handler= ' error ', add_ Help=true)

The parameters have default values, which are printed when the program is run because of incorrect parameters or when the Parser.print_help () method is called. It is generally only necessary to pass the parameter description.

Add_argument (name or flags ...) [, Action] [, Nargs] [, Const] [, Default] [, type] [, Choices] [, Required] [, help] [, Metavar] [, Dest])

The common parameters are explained as follows:

Name or Flags: command-line parameter name or option, such as-P,--port

Action

Store: Default action mode, store value to specified variable

Store_const: Store values specified in the const section of the parameter, commonly used to implement non-Boolean command-line flag

Store_true/store_false: boolean switch. The default value of Store_true is False, which is true if the command line has input of the boolean switch. Store_false opposite

Append: Stores the value to the list, which can be reused

Append_const: Store value to list, store value specified in const part of parameter

Count: Number of inputs for shorthand for statistical parameters

Version: Output release information, and then exit the script

Nargs: The number of command-line arguments, generally denoted by a wildcard:? Represents only one, * represents 0 to more, + represents 1 to more

Default: Defaults

Type: Types of parameters, default to string, or float, int, and BOOL

Choices: Enter a range of values

Required: The default is False, or true to indicate that the parameter must be entered

Help: Helpful Tips for using

Dest: The corresponding variable name of the parameter in the program, such as: Add_argument ("-A", dest= "Code_name"), using Parser.code_name in the script to access the value of the command-line option

The sample script test_argparse.py code is as follows:

1 #encoding =utf-8 2 Import argparse 3 4 def main (args): 5 print ("--address {0}". Format (args.code_address)) #args. A Ddress will error, because the value of dest is specified 6 print ("--flag {0}". Format (Args.flag)) #如果命令行中该参数输入的值不在choices列表中, error 7 print ("--port {0} . Format (args.port) #prot的类型为int类型, if the option is not entered on the command line, the error is 8 print ("-l {0}". Format (Args.log)) #如果命令行中输入该参数 This value is true. Because the alias "--log" is specified for the short format "-L", the program uses Args.log to access 9 if __name__ = = ' __main__ ': one parser = Argparse. Argumentparser (usage= "It's usage tip.", description= "help info.") Parser.add_argument ("--address", default=80, help= "the port number.", dest= "code_address") parser.add_argumen T ("--flag", choices=['. txt ', '. jpg ', '. xml ', '. png '], default= ". txt", help= "the file Type") parser.add_argument ("--p Ort ", Type=int, Required=true, help=" the port number. ") Parser.add_argument ("-L", "--log", Default=false, action= "Store_true", help= "active log info.") + args = Parser.parse_args () main (args)

Run the following command, respectively:

Python test_argparse.py

Python test_argparse.py--port 80

Python test_argparse.py--port--flag apk

Python test_argparse.py--port 80-l

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