What is Python Pexpect Module? - tpointtech/Python GitHub Wiki

Python Pexpect Module

We are all familiar with desktop operating systems, and their features and how they work. The most well-known operating systems that most of us have heard of include Windows, Linux, macOS and ChromeOS. Of them, chromeOS is also an operating system based on Linux for desktops which boosts the popularity of Linux and other Linux-based operating systems. Linux is a very well-liked operating system for programmers and developers due to the improved security features. However it's not so widely used by the general public The main reason for this is the complicated commands that are used to run and work on the Linux desktop operating system.

In the present, we are talking about Linux which is an operating system for desktops from the UNIX family of operating systems that was first introduced by Linus Torvalds back in 1991 on 17 September. In addition to its security features one of the reasons, or it is said to be the most appealing thing about Linux is that it's an open source and free-license software that is based on the FOSS (Free Open Source Software) model. In contrast to windows and other operating systems for desktops, Linux is absolutely free and users can download the latest version along with a variety of different distributions. Other benefits that Linux provides developers include faster interpreters, faster compilers, the possibility to create a customization that is heavy and lower OS complexity and many other. However, what happens if we don't have a Linux OS and still want to make use of Linux commands.

There are numerous reasons for taking this step, for instance, you want to get acquainted to Linux commands, for instance. It's possible that not every programming language, but Python provides this possibility to execute Linux commands on Windows or any other operating system. To accomplish this, Python has the pexpect module, which provides us with the option of automating Linux commands with the use of a Python program by using its functions. So, we'll be able to learn more about the pexpect Module of Python and discover the way to execute Linux commands using an Python program that uses it.

The introduction to Pexpect the module in Python

Pexpect is an Python program that performs numerous functions, like automating Linux commands using Python programs, creating child processes, and then managing them automatically, etc. The Pexpect module is an extremely robust module of Python that includes a variety of functions for performing various tasks. The Python Pexpect module functions as a span child and it reacts to the pattern that we define it using Python. Python program to carry out a variety of tasks.

Here are some of the useful tasks that we can carry out with the pexpect module in Python:

FTP passwords,

ssh,

Telnet,

Automating Linux commands and many other commands

Install of Python Pexpect Module

Pexpect isn't an in-built module of Python (it does not install in it as part of the Python installation) This is the reason when this module isn't already present in our system we must perform the installation. First, we must ensure that the Python pexpect program is installed in the system, or not since it is not possible to execute the implementation without this module in our system. If the Pexpect module has currently not present in our system, then we can install the module using various ways, and of all possible methods of installation that install the module using Pip's installer will be the most straightforward and quickest.

We will therefore use the pip installer for installing the module on our system. In this manner, we'll make use of the following pip install command:

****Pip installation pexpect

You must type the command above in the terminal shell of command prompt following the commands, we will need to hit enter to ensure it is possible for the installer to can begin installing the module into our system. Once the installation of this module starts it will take time to install the module successfully in our system and we'll have to be patient until it is done.

****Python Pexpect Module

As you can observe, a successfully installed message appears on our screen. This indicates that the pexpect module has been successfully installed on our system. The next step is to continue by implementing this Pexpect module and begin by importing it into examples applications to see how it works.

****Automating Linux Commands using Pexpect Module

In this section it will help us automate Linux commands using Python programs by importing this module called the Pexpect module into these programs. There are three ways to use the pexpect program, which we can utilize to automate Linux commands with an Python program.

Three methods of the pexpect module that we can utilize in order to make it easier for us to execute Linux commands:

Using run() method

By using the method of spawn classes

Using sendline() method

We will learn about the execution of each of the three approaches which are described above by using the examples in a program. We will make use of a different sample software for each method, and then automate the Linux command using it.

Note: All of the methods in the pexpect module described above will only work on operating systems based on UNIX None of them are compatible for windows. If we attempt to use these methods, or even the example applications, we will see some errors on the results. The first step is to create an Virtual environment for the UNIX-based OS, in order to run these applications on Windows. Windows operating system.

Method 1: Using run() Method

There is the running() function within the pexpect program, which allows us to execute and run an command. It can be used with the pexpect.run() technique to run an Linux command by supplying it as an argument to the function. Afterwards we can display the results of the operation in the output. Run() function could be used to substitute for that of the os.system method which can be employed to run Linux commands.

Method 2: Utilizing Spawn Class Method

In this way we will make use of an spawn class which will aid us in automatizing the Linux commands provided in the program. Spawn class provides the main interface through which we create a new child process in the course of execution and control it using child classes. The argument string we provide in the spawn class may be replaced with the command shell (whenever necessary) and is executed by the program.

Method 3: Applying the Sendline Method

In this case we will employ this sendline() function after we have started the child process using the child process's spawn class. Sendline() method writes across the character for the pattern that is defined for the process that is being created by it. Sendline is also utilized to report the amount of bytes used in the pattern that is defined by us, however, we will employ this technique for matching patterns that match input strings within this part. This method is employed for automating the Linux command whenever we create an input string for your child processes.