Tips for Writing Efficient Bash Scripts: Best Practices for System Administration

In modern computing, Bash scripts are an indispensable tool for system administrators. They provide automation for repetitive and time-consuming tasks, allow for the customization of system management, and enable devops to carry out complex operations.

However, despite their usefulness, Bash scripts require careful handling during development to ensure efficient execution and maintainability. In this article, we will discuss the best practices in Bash scripting for system administration.

1. Use Comments and Documentation

Comments are critical for clarity and comprehension of your scripts. They should help anyone who approaches the script understand the functions of the code blocks, relationship between functions, and the inputs/outputs.

Documentation is equally important. Start with a brief description of the script, followed by step-by-step instructions for using it. Ensure that your document covers the script’s purpose, input and output variables, and any significant files or application resources referenced in the code.


    #!/bin/bash
    
    # Description: 
    # Author: 
    # Date: 
    
    # Set variables
    name="World"
    
    # Print Hello World
    echo "Hello $name!" # This is a comment

2. Use Functions

Using functions is an excellent way to write reusable code, enhance the organization of the code, and make debugging easier. By putting your code into functions, you can call the function as many times as you want, rather than replicating the code each time.


  # Function
  function hello {
    # Set variables
    name="World"
  
    # Print Hello World
    echo "Hello $name!"
  }
  
  # Call function
  hello

3. Use Array

Array variables allow you to store and process groups of data. For instance, you might need to process a list of user accounts or multiple file paths.

Assuming that your script takes two filenames, this code block demonstrates how to pass multiple arguments using an array.


    #!/bin/bash
    
    files=(
      file1.txt
      file2.txt
      file3.txt
    )
    
    for file in "${files[@]}"; do
      echo "Processing $file"
      # call a function that processes each file
    done

4. Use Error-handling Mechanisms

Using exception handling, try-catch blocks, and conditional statements are critical to Bash scripts to manage errors in a controlled manner.

If any of the commands fail, the script aborts, and no further impact occurs. As a result, it is necessary to test the return code from each command or to test for the existence of required configuration files.


    # Test if user has root privilege
    if [[ $EUID -ne 0 ]]; then
       echo "This script must be run as root" 
       exit 1
    fi

5. Use Proper Indentation

Proper indentation improves code readability, making it easier for others to understand and maintain your code.

This example uses proper indentation, making it easy to distinguish between loops, functions, and conditional statements.


    #!/bin/bash
    
    function hello {
      # Set variables
      name="World"
    
      # Print Hello World
      echo "Hello $name!"
    }
    
    while read p; do 
      echo "$p"
    done < file.txt
    
    for i in $(ls); do
      echo $i
    done
    
    if [[ $USER == 'root' ]]; then 
      echo "Hello root!"
    else
      hello
    fi

Bash scripting is a valuable tool for sysadmins, but it is important to follow best practices. Proper function use, indentation, and documentation all contribute to efficient code and reproducible processes. Using arrays and error-handling mechanisms are also important when managing lists of arbitrary size and potential execution failure, respectively. Following these tips will help you write more efficient Bash scripts.

As with the humorous and informative Fortune displays you can set up as your login terminal, why not add a fun line of code to your script that prints an uplifting statement upon task completion? Here's a suggestion:


    #!/bin/bash
    
    echo "Script running"
    
    # Run your commands and tasks here
    
    echo "All tasks succesfully completed. You're a rockstar admin!"

Have fun experimenting with your Bash scripts, and keep learning!

Also related: