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Programming & Scripting

Bash Shell Scripting Definition

Bash
Bash is a command language interpreter. It is widely available on various operating systems and is a default command interpreter on most GNU/Linux systems. The name is an acronym for the ‘Bourne-Again SHell’.
Shell
Shell is a macro processor which allows for an interactive or non-interactive command execution.
Scripting
Scripting allows for an automatic commands execution that would otherwise be executed interactively one-by-one.

Bash Shell Script Basics

Do not despair if you have not understood any of the above Bash Shell Scripting definitions. It is perfectly normal, in fact, this is precisely why you are reading this Bash Scripting tutorial.

In case you did not know, Bash Scripting is a must skill for any Linux system administration job even though it may not be implicitly requested by the employer.

What is Shell

Most likely, your are at the moment sitting in front of your computer, have a terminal window opened and wondering: "What should I do with this thing?"

Well, the terminal window in front of you contains shell, and shell allows you by use of commands to interact with your computer, hence retrieve or store data, process information and various other simple or even extremely complex tasks.

Details
Programming & Scripting

Objective

Understanding the base concepts behind udev, and learn how to write simple rules

Requirements

  • Root permissions

Difficulty

MEDIUM

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

In a GNU/Linux system, while devices low level support is handled at the kernel level, the management of events related to them is managed in userspace by udev, and more precisely by the udevd daemon. Learning how to write rules to be applied on the occurring of those events can be really useful to modify the behavior of the system and adapt it to our needs.

Details
Programming & Scripting

Objective

Learn to use the argparse module to easily parse python scripts parameters

Requirements

  • Basic knowledge of python and object oriented concepts

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

In a previous article we have seen how to parse command line arguments using getopts in the context of bash scripts (you can find the article here). Now we will see how to accomplish the same task, in a more powerful way, when writing a python script.

Details
Programming & Scripting

Objective

Play audio with VLC in Python.

Distributions

This will work on any Linux distribution

Requirements

A working Linux install with Python and VLC.

Difficulty

Easy

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

There are plenty of ways to play audio files with Python. It really depends on your application, but the easiest way, by far, is to use the bindings for VLC to control VLC with Python, and play your files.

With VLC, you don't need to worry about codecs and file support. It also doesn't require too many complicated methods, and/or objects. So, for simple audio playback, VLC is best.

Details
Programming & Scripting

Objective

Consume a JSON API in Python.

Distributions

This will work on any Linux distribution.

Requirements

A working Linux install with Python.

Difficulty

Easy

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

One of the main reasons that you'd like to work with JSON in Python is consuming APIs. There are hundreds of excellent public APIs out there and ready to use in your application. Even huge players on the web, like Facebook and Twitter, out out APIs for you to work with.

You can build entire applications around API data, including building web applications that aggregate, manipulate, and display that data in a convenient way.

Details
Programming & Scripting

Objective

Encode Python data into JSON.

Distributions

This will work on any distribution with Python installed.

Requirements

A working Linux install with Python

Difficulty

Easy

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

JSON is the universal format for passing data between programs and/or languages, especially on the web. Python has excellent built-in support for converting data from a Python program into JSON for another program to use.

Details
Programming & Scripting

Objective

The objective of this tutorial is to describe how to use the bash shell trap builtin to make our scripts able to perform certain actions when they receive a signal or in other specific situations.

Requirements

  • No special requirements

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

bash scriptingWhen writing scripts that are meant to run for a considerable time, it's very important to increase their robustness by making them able to react to system signals, executing specific actions when some of them are received. We can accomplish this task by using the bash trap builtin.

Details
Programming & Scripting

Objective

The objective is to use command line and bash shell script to obtain Sunrise & Sunset time information for any given location.

Operating System and Software Versions

  • Operating System: - Linux distribution agnostic.

Requirements

Installed lynx tool and access to shell command line. Your location code obtained from https://weather.codes/search/.

Difficulty

EASY

Conventions

Details
Programming & Scripting

Objective

Learn how to use the bash getopts builtin to parse a script options

Operating System and Software Versions

  • Operating System: - All Linux distributions

Requirements

  • No special requirements, just access to a bash shell

Difficulty

MEDIUM

Conventions

Details
Programming & Scripting

Introduction

The following post is a little bit different from my other posts as it does not solve any of your Linux configuration problems. Apologies there! This post is an attempt to kill multiple birds with one stone, hence expose children to a command line, avoid web flash and ads driven multiplication practice tests online and most importantly gain some multiplication skills along the way.

My daughter reached the age where she is required to perform multiplication calculation at school. So together we have developed a below Bash script to take her 1x1 to 10x10 multiplication tables practice to the next level. She approved all the output colours with a "cool" mark, and to my surprise, she was very quickly able to correct my forgotten closing quotation marks during the development thus significantly improving development efficiency:-)

Details
Programming & Scripting

Objective

Install ZSH with Oh My ZSH and learn the basic features.

Distributions

ZSH is available in the repositories of nearly every distribution.

Requirements

A working Linux install with root privileges.

Difficulty

Easy

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

Bash isn't bad. It gets the job done just fine, but have you ever considered what it'd be like if Bash had some extra features to make it more convenient to work with? That's more-or-less what ZSH is.

It includes all of the features that you'd expect from Bash, but it also has some really nice additions to make your life easier. Actually, you'll be amazed at how much easier they make working in the command line.

Details
Programming & Scripting

Objective

Learn to use redirections, pipes and tee in the Bash shell

Operating System and Software Versions

  • Operating System: - Linux distribution agnostic

Requirements

  • Access to a Bash shell

Conventions

Details
Programming & Scripting

Introduction

Python will let you know when you get your syntax wrong. It'll immediately fail and not allow your program to run.

What about when your code has a different type of problem? Those are called exceptions, and they tend to be harder to catch. It's up to you to recognize situations where hey might come up and catch them to prevent your program from crashing altogether.

Imagine a scenario where you need user input. Do you want your program to crash every time a user mistypes something or enters something erroneous? That's far from ideal. Since you know there could be a problem there, you can tell Python to look out for one, and recover gracefully.

Details
Programming & Scripting

Introduction

Python is a powerful scripting language. So, why not use it to script Linux? The os module is Python's answer to handling many Linux file operations.

The os module allows Python to perform many of the file and folder operations that you'd typically carry out in the Linux command line. It enable you to begin swapping out Bash for Python, which makes for a much cleaner and friendlier scripting experience.

Loading OS

The os module is a Python module like any other. In any script where you want to use it, you can use an import statement to pull it in. 
import os

getcwd()

The getcwd() method returns the current working directory in the form of a string. You don't need to pass it anything. It's roughly the equivalent of pwd. 
print(os.getcwd())

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