How to Run a Shell Script in Linux

Yes, Bash scripting is a good skill for any developer, system administrator, or power user who wants to automate repetitive tasks and make their workflow more efficient. There are various online resources where you can learn Bash scripting. Visit the guide Change Permissions of Directories and Files Recursively with “chmod” to clearly understand File permissions in Bash. The Bash function really helps break down your scripts into smaller ones and make them more manageable and organized.

Bash is quite easy to learn, with many learners mastering both basic and advanced commands in about half a year. There are several methods to read a file, with the cat command being the most popular one. On line 2, “days” automatically becomes a variable, with the values being the day names that follow. Then, in the echo command, we use the $ symbol to call the variable values. The script compares the variable a with the value 20 and the variable b with the value 50.

Use echo statements

On the other hand, the until loop always executes at least once. Yes, you can execute a Bash script in Python by using the subprocess module to run the Bash script as a subprocess. This allows you to invoke and execute Bash commands or scripts within your Python code. The provided Bash script demonstrates a simple example of sending an email using the mailx command.

• Expressions that produce a boolean result, either true or false, are called conditions.
• By mastering Bash scripting, users can harness its power to optimize their workflow and enhance system administration tasks on Linux platforms.
• Command-line arguments are parameters passed to a script at the time of execution.
• In this example, a function attempts to create a directory.
• There’s also a way to have a script run by the current shell, not a shell launched specifically to execute the script.

Basically, to create a local variable, you need to use the term ‘local’ before the variable name. In order to successfully create your first bash script, you need to understand the essential bash commands. They are the main elements of a script, and you must know what they do and how to write them properly. The case statement provides a way to execute different blocks of code based on the value of a variable.

A typical Bash script starts with a shebang (#!/bin/bash), which indicates the directory or path to the Bash interpreter. After the shebang, one can define variables and functions, use conditionals and loops and execute built-in commands like any other programming language. Bash scripting involves understanding fundamental concepts such as variables, control structures, functions, parameters, etc. Variables in Bash are used to store and manipulate data. You can assign values to variables and access them later in the script. Functions provide modularity and code reusability by encapsulating a set of instructions that can be called multiple times.

How to Use Multiple If Statements in Bash Scripts

If it is, the script outputs that the number is positive. If the number is not greater than 0, the script moves on to the next statement, which is an if-elif statement. Here, the script checks if the number is less than 0. If it is, the script outputs that the number is negative. Finally, if the number is neither greater than 0 nor less than 0, the script uses an else statement to output that the number is zero.

Elementally, it’s more like a script within a script. The for loop iterates over the sequence of values like arrays, range of numbers, or list of items. Streams refer to a continuous flow of data that either receives texts in or feeds texts out ceaselessly.

Then the read command prompts the user to enter a value and assigns it to input. The while loop evaluates whether the input is not equal to “q” or not equal to “Q”. If the user’s input is not q or Q, it prompts a message by pressing “q” to quit. The read command captures the user’s next input, updating the value of input for the next iteration. The provided script allows users to input two numbers and calculate their sum. When executed, it prompts the user to enter a number, which is stored in the variable num1.

Here we’ll discuss some methods to receive output from the scripts. In this section, we’ll discuss some methods to provide input to our scripts. Following these naming conventions helps make Bash scripts more readable and easier to maintain. Comments are very helpful in documenting the code, and it is a good practice to add them to help others understand the code.

This example demonstrates how echo can be deadman used to display text and the results of simple commands and variables. The local variables are only confined to the blocks of code or functions where they are already declared. Bash doesn’t understand local variables outside of those blocks.

By using the Unix pipe character ‘