Can a Bash Script Be Used to Run Another Bash Script?

In the world of Bash scripting, running one script from another is a common and useful technique. This practice not only enhances reusability but also allows for better organization and modularity. In this article, we will explore how to achieve this, the benefits it offers, and provide practical examples.

The Basics of Running a Bash Script from Another

In the context of Bash scripting, a script file can be executed from another script using the same method as any other command. However, there are two primary ways to go about this:

Calling the Second Script as an External Command: This method involves making the second script executable by changing its permissions and then calling it within the first script just like any other command. Inlining the Second Script: Another approach is to include the code of the second script directly within the first script. This is achieved by using the . command followed by a space and the name of the second script.

Executing a Script as an External Command

If you prefer to maintain a separation between scripts, you can make the second script executable and then run it from the first script. This method allows each script to have its own set of functions and variables, making the codebase cleaner and more modular. Here's how to do it:

Write and Save the Second Script: Create a new Bash script for the functionality you want to reuse. Make the Script Executable: Use the chmod command to change the permission of the second script. For example, chmod x Call the Second Script from the First: In the first script, you can call the second script by simply writing its name and any necessary arguments.

Including a Script Inline for Reusability

If you prefer to keep your code in a single file or want certain parts of the script to be user-defined, you can inline the second script within the first. This method allows for reusability and better integration of code. Here's how it works:

Write the First Script: Create the main script with the general functionality. Use the . Command to Include the Second Script: Add a line starting with . followed by a space and the name of the second script. This will execute the second script inline within the first script. Keep the Variables Shared: Inline scripts share the same variables and other stateful information, making it easy to pass data between sections of the script.

Practical Examples

Let's consider a practical scenario where we have a script that needs to perform two tasks sequentially:

Example 1: Executing a Script as an External Command

Consider a script for backing up a directory and then cleaning up old files:

#!/bin/bash# Second script for cleaning up old filesbackup_and_clean() {    backup_directory  clean_old_files}backup_directory() {    # Code for backing up the directory    echo "Backup complete.