thpeetz-notes/Clippings/10 Best Practices for Writing Bash Scripts.md

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10 Best Practices for Writing Bash Scripts	https://medium.com/@talhakhalid101/10-best-practices-for-writing-bash-scripts-95d57e675939	Talha Khaild	2024-08-20	2024-10-29	Everyone who has come to this corner of mine, must for one reason or another, knows that I really like using the terminal, automating “scripting” everything I can, including my current desktop…	clippings

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Everyone who has come to this corner of mine, must for one reason or another, knows that I really like using the terminal, automating “scripting” everything I can, including my current desktop system, which today is still i3wm. Well, for this task we use our beloved terminal, regardless of the shell you use, these tips will be useful. Definitely if you are new to GNU/Linux, then you will find yourself face to face with the bash shell.

A Bash Script is a file in which multiple shell commands are coded to perform a particular task, this article includes some healthy habits for writing a script, mainly to improve efficiency and make it more readable.

1. Comment the code

Definitely something basic, but one that many forget and that is always very useful, either for yourself, or for others who want to review or modify your script, it is undoubtedly decisive in achieving clean code that can explain various parts of complex codes. While you are focused on writing the script, it is easy to get confused with the code you have written as time goes by. It is also effective when working in a group on a large project, as it helps you understand what the function or method actually does.

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2. Using Functions

As you may know, a function is a set of commands grouped together to perform a specific task that helps to modulate the workflow, eliminating code repetition. It makes the code cleaner and more readable, as well as easier to maintain.

#!/bin/bashfunction check_root() {   echo "function has been called"; }

3. Using double quotes

Using double quotes will help eliminate unnecessary globbing as well as word splitting, including whitespace, when variable values ​​contain a separator character or a whitespace.

4. Terminate execution on error

Sometimes, when running a script, there may be some execution error. Even if a command is not executed, the script may continue to run and affect the other commands in the script. To avoid further logical errors, we should include set -o errexit or set -e to terminate the command in case of error.

#!/bin/bash set -o errexit

5. Declaring Variables

Declare the variable according to its data type and usage. When the variable is not declared, bash may not be able to execute the related command. Variables can be declared globally or locally in the script. For example:

#!/bin/bash declare -r i=30function my_variable(){  local -r name="${HOME}"}

6. The use of keys

Bind variables with curly braces while using variable concatenation with strings to avoid unnecessary use of variables. This also helps to easily identify the variable while using it in a string. For example:

#!/bin/bashset -o errexitdata="${USER}_data is being used"

7. Replacing the command

While assigning the output of the command to the variable, bash uses the command substitution feature. We need to use $() instead of backticks to assign the output to variables as recommended.

#!/bin/bash set -o errexit date_now=$(date)

8. Variable Nomenclature

In our system, all environment variables are named using uppercase letters. So when we declare a local variable, we should declare it using lowercase letters to avoid conflicts between the environment and local variable name.

#!/bin/bash set -o errexit ser_var="$HOME is your correct login."

9. Declaring Static Variables

If you have static data that remains unchanged throughout the script, you can assign the value to a static variable whose value cannot be modified. You can declare the static variable using the read-only command.

#!/bin/bashreadonly test_conf_path="/etc/nginx/conf.d/test.conf"

10. Debugging

Debugging is the most essential part to identify a problem. We can check the syntax error of the script, so to check it we need to run the bash script with -n using the bash command.

$ bash -n script_name

Additionally, we can enable and run the script in debug mode using the following command.

$ bash -x script_name

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Conclusion

So far, I’ve left you with some good bash scripting practices that you can apply to other languages. Adopting them will undoubtedly help you improve your scripts and, most importantly, it’s a good way to leave your code clean and tidy, as well as documented and easy to understand/maintain.

Until another article, reader, good vibes.