Python Getopt Module

Python Getopt Module

Python Getopt module is a parser used for analyzing command-line options. It is a parser used to analyze arguments in sys.argv. Parsing command line arguments means dividing the commands into smaller parts and trying to understand them.

Python getopt() module is similar to the getopt() module in C language. It divides the command into smaller sections and analyses the same.

How to Install Getopt Module ?

Before getting into the detailed syntax of the Python Getopt module let's see how to install this module in python. The getopt module is an inbuilt module pre-included in Python.

1. To install the python package in your system you can first install the pip package. Without the "pip" package you cannot install the python package.

2. Now after installing "pip" we can install the Python package.

   After successfully installing python we can directly use the getopt module like other inbuilt modules in python by importing.

Getopt Function in Python

The first and main function provided by this module is the same as the name of the module i.e. getopt() function. The primary function of this function is to parse command-line options and parameter lists. Let's look into the detailed syntax and parameters of the Getopt function of the Getopt module.

Syntax

Parameters

As mentioned in the syntax of the Python Getopt function the parameters passed to the function are as follows :

• args
• options
• long_options The significance of these parameters is explained below.

Arguments: args :

The args is the list of arguments passed to the function. It is the classification of the arguments to be analyzed and it's generally derived from the sys.argv[1:] argument sequence.

Short Options: options :

This is the second parameter passed to the function. The options are the string of option letters that the script needs to recognize. It is the option definition for single-character options. For options that require a single character argument, then its letter is followed by a colon ':'.

Example :

Long Options :

This is the third parameter passed to the python getopt function. It is the sequence of the string with names of long-style options. Long option names can be consisting of more than one single character and its name should have the prefix '- -'.

For example : - - noargument or - - withargument. If any longoption needs an argument, then it should be followed by an equal to '=' sign.

Example :

Return Type

The return type of the function getopt() function consists of two types of elements. The first element is a list of (option, value) pairs, and the second element is a list of arguments that are left when the options list was stripped.

Examples for Understanding

Example - 1 :

Here we will see how to use short options in the python getopt function.

Output :

In the above example, the user has created a function fullname(). This function takes first_name and last_name as arguments from the command line and prints the name. Here we have provided the arguments as a shortoption that shows the first name as f and the last name as l. The user here has entered his first name as 'USER' and the last name as 'NAME'. The final output is returned by the function fullname() as 'USER NAME'.

Example - 2 :

In this example, we will see how to use longoption and use the full form as 'first_name' and 'last_name' for the same short forms 'f' and 'l' used in the last example.

Output :

In the above example, the user has created a function fullname(). This function takes first_name and last_name as arguments from the command line and prints the name. Here we have provided the arguments as longoption which shows the first name as first_name and the last name as last_name. The user here has entered his first name as 'USER' and the last name as 'NAME'. The final output is returned by the function fullname() as 'USER NAME'.