1. sys.argv
2. argparse
3. getopt
4. click
Last
Hello everyone , In daily writing Python In the process of scripting , We often need to pass in some variable parameters in combination with command line parameters , Make the project more flexible and convenient
In this article, I will list the build Python Of command line arguments 4 There are two common ways
They are ：
built-in sys.argv modular
built-in argparse modular
built-in getopt modular
Third party dependency Library click
1. sys.argvEasiest to build command line parameters 、 A common way is to use the built-in 「 sys.argv 」 modular
It passes parameters in an ordered list , Therefore, the order of parameter transfer must be fixed
therefore , This method is applicable to projects with few parameters and fixed scenarios
import sysif __name__ == '__main__': # Get parameter list # Be careful ：sys.argv[0] Represents the first parameter , namely ： Script name 「1_sys.argv.py」 # List of other parameters args = sys.argv[1:] # Number of parameters args_length = len(sys.argv) if sys.argv else 0 print(" Exclude run master file parameters , Other parameter lists are :", args) print(" Total number of parameters ：", args_length)# Use # python3 1_sys.argv.py arg1 arg2# Exclude run master file parameters , Other parameter lists are : [arg1, arg1]# Total number of parameters ：3It should be noted that , Pass... In the script 「 sys.argv 」 Get the parameter list , The first parameter represents the name of the script main file
2. argparseBuilt in argparse The module can easily write friendly command line parameter scripts , And it can automatically generate help manuals , Clear error messages can be thrown when the user passes invalid parameters into the program
Official documents
Use it to build command line arguments that contain 3 A step ：
Build parameter resolution object add parameter add parameter resolution parameter
1. Build command line parameter parsing object
import argparse...# Build a command line parameter parsing object parser = argparse.ArgumentParser(description=' Command line arguments ')...2. Add command line arguments
It's important to point out that ,--arg1 Used to specify the parameter name ,-a1 representative dest Target variable value （ Abbreviation ）
...# Set up 3 Parameters # Parameters 1：arg1, integer , It is not necessary to pass in parameters # Parameters 2：arg2, character string , It is not necessary to pass in parameters , Include default values 「xag」# Parameters 3：arg3, String type , Parameters that must be passed in parser.add_argument('--arg1', '-a1', type=int, help=' Parameters 1, Not a required parameter ')parser.add_argument('--arg2', '-a2', type=str, help=' Parameters 2, Not a required parameter , Include default values ', default='xag')parser.add_argument('--arg3', '-a3', type=str, help=' Parameters 3, Necessary parameters ', required=True)...3. Analyze the parameter value
...# Analytical parameters , Get all command line parameters （Namespace）, Then turn it into a dictionary args = vars(parser.parse_args())# Get all parameters print(" All command line parameters are :")for key in args: print(f" Command line parameter name :{key}, Parameter values :{args[key]}")...When you use it , We can go through 「 -h / --help 」 Command parameters view help documentation
# View the command line parameter help documentation python3 2_argparse.py --help# or python3 2_argparse.py -hAdded above 3 Parameters , Parameters arg1、arg2 Non mandatory value transfer ,arg3 Must pass value , Another parameter arg2 Default value specified
# Parameters arg3 must , Parameters arg1 And parameters arg2 Not necessary , The parameter arg2 Set the default value # Pass in the parameter arg3# python3 2_argparse.py --arg3 123# python3 2_argparse.py -a3 123 [email protected] args % python3 2_argparse.py -a3 123 All command line parameters are : Command line parameter name :arg1, Parameter values :None Command line parameter name :arg2, Parameter values :xag Command line parameter name :arg3, Parameter values :123# Pass in the parameter arg1、[email protected] args % python3 2_argparse.py -a1 111 -a3 123 All command line parameters are : Command line parameter name :arg1, Parameter values :111 Command line parameter name :arg2, Parameter values :xag Command line parameter name :arg3, Parameter values :123# Pass in the parameter arg1、arg2、[email protected] args % python3 2_argparse.py -a1 111 -a2 222 -a3 123 All command line parameters are : Command line parameter name :arg1, Parameter values :111 Command line parameter name :arg2, Parameter values :222 Command line parameter name :arg3, Parameter values :1233. getoptgetopt yes Python A built-in standard module in , Can combine sys.argv modular , Directly parse script runtime parameters
Use format ：getopt(args,shortopts,longopts = [])
among
args
parameter list , Can pass sys.argv obtain , You can refer to the above
shortopts A string consisting of short parameters
Define short parameters , If the parameter has a value , You need to append a... After the short parameter 「 : 」 Symbol
How to use parameters ：-n 23
longopts Long parameter list
When defining a long parameter list , If a parameter has a value , You need to append a... After the short parameter 「 = 」 Symbol
How to use parameters ：–port 8080
Take the incoming database connection parameters as an example （ Parameters include ip、 user name 、 password 、 Database name ） Explain
from getopt import getoptimport sys# To obtain parameters # sys.argv[1:]： Get all the command line parameters except the script file name # opts： A tuple list of all options and their input values # args： Remove the rest of the useful input opts, args = getopt(sys.argv[1:], 'i:u:p:d:', ['ip=', 'user=', 'pwd=', 'db='])# Get parameter value # Short parameters # python3 4_getopt.py -i 127.0.0.1 -u root -p 123456 -d mysqldb# Long parameters # python3 4_getopt.py --ip 127.0.0.1 -u root -p 123456 -d mysqldbip_pre = [item[1] for item in opts if item[0] in ('-i', '--ip')]ip = ip_pre[0] if len(ip_pre) > 0 else Noneprint(" Parameters ip：", ip)user_pre = [item[1] for item in opts if item[0] in ('-u', '--user')]user = user_pre[0] if len(user_pre) > 0 else Noneprint(" Parameters user：", user)pwd_pre = [item[1] for item in opts if item[0] in ('-p', '--pwd')]pwd = pwd_pre[0] if len(pwd_pre) > 0 else Noneprint(" Parameters pwd：", pwd)db_pre = [item[1] for item in opts if item[0] in ('-d', '--db')]db = db_pre[0] if len(db_pre) > 0 else Noneprint(" Parameters db：", db)When running the script , We can use 「 Short parameters 」 or 「 Long parameters 」 Transfer in form
# test # Short parameters python3 4_getopt.py -i 127.0.0.1 -u root -p 123456 -d mysqldb# Long parameters python3 4_getopt.py --ip 127.0.0.1 --user root --pwd 123456 --db mysqldb4. clickclick As a third-party dependent Library , It encapsulates a number of methods for command-line tools , It is very convenient to implement command line parameters
Project address
First , We need to install dependency Libraries click
import click# Installation dependency # pip3 install -U [email protected]()@click.option('--arg1', default='111', help=' Parameters arg1, The default value is 「111」')@click.option('--arg2', type=int, help=' Parameters arg2')@click.option('--arg3', type=str, help=' Parameters arg3')def start(arg1, arg2, arg3): """ Based on parameters arg1、 Parameters arg2、 Parameters arg3 Run the project :param arg1: :param arg2: :param arg3: :return: """ print(" Parameters arg1 The value is :", arg1) print(" Parameters arg2 The value is :", arg2) print(" Parameters arg3 The value is :", arg3)if __name__ == '__main__': start()then , You can configure parameters on the main running function through the decorator
such as , The above defines 3 Two command line arguments arg1、arg2、arg3, And set the parameter type and default value
Last , When running the script, you only need to pass the corresponding value according to the parameter settings
# No parameters [email protected] args % python3 3_click.py Parameters arg1 The value is : 111 Parameters arg2 The value is : None Parameters arg3 The value is : None# Include parameters [email protected] args % python3 3_click.py --arg1 test1 Parameters arg1 The value is : test1 Parameters arg2 The value is : None Parameters arg3 The value is : None# Include parameters arg1、arg2# Be careful ：arg2 The parameter type of is integer , The passed in parameter must be able to be converted to an integer , Otherwise, an error will be reported [email protected] args % python3 3_click.py --arg1 test1 --arg2 222 Parameters arg1 The value is : test1 Parameters arg2 The value is : 222 Parameters arg3 The value is : None# Include parameters arg1、arg2、[email protected] args % python3 3_click.py --arg1 test1 --arg2 222 --arg3 test3 Parameters arg1 The value is : test1 Parameters arg2 The value is : 222 Parameters arg3 The value is : test3 Last The above explains the implementation through an example Python Command line arguments are common 4 Ways of planting
For some simple and informal scenarios , Personally, I think we can consider using sys.argv Modules quickly build command line parameters ; For some parameters, there are many 、 Formal production environment for users , It is suggested to make use of argparse Module or click Dependency to create command line parameters
This is about Python This is the end of the article explaining the four ways of command line parameterization , More about Python For the parameterized content of the command line, please search the previous articles of the software development network or continue to browse the relevant articles below. I hope you can support the software development network in the future ！
