When it comes to writing scripts in bash or zsh, you may have noticed a peculiar syntax when it comes to using the "case" statement. Instead of the traditional format of using curly braces and semi-colons, the "case" statement in these scripting languages uses a different set of symbols. So, why does the "case" statement in a bash/zsh script have a weird syntax? Let's dive in and find out.
First and foremost, it's important to understand what the "case" statement does in a bash or zsh script. In simple terms, it allows a script to perform different actions based on the value of a variable. It's similar to an "if" statement, but with the added benefit of being able to match multiple values instead of just one. This makes it a useful tool for handling different scenarios in a script.
Now, let's take a look at the syntax of the "case" statement in bash and zsh. It starts with the keyword "case" followed by the variable or expression that will be evaluated. Then comes the "in" keyword, followed by a list of possible values or patterns that the variable can match. Each of these values or patterns is followed by a set of statements enclosed in double parentheses, which are known as "cases". Lastly, the statement ends with the keyword "esac" which is simply "case" spelled backwards.
So, why is this syntax different from the traditional curly braces and semi-colons? The answer lies in the history of these scripting languages. Bash and zsh are derived from the original Bourne shell, which was developed in the late 1970s. Back then, computers had limited memory and processing power, so developers had to come up with ways to optimize their code. In the case of the "case" statement, using the double parentheses instead of curly braces and semi-colons was a way to save memory and improve performance.
But why not just stick to the traditional syntax? Well, over time, as these scripting languages evolved, the unique syntax of the "case" statement became a part of their identity. It also allowed for a more concise and readable code, as the double parentheses visually separate the different cases and make it easier to understand the logic of the script.
Another reason for the strange syntax of the "case" statement in bash and zsh is compatibility. These languages are used on a variety of operating systems, and some may have different implementations of the "case" statement. By using a unique syntax, it ensures that the script will work on any system without any compatibility issues.
In conclusion, the "case" statement in a bash/zsh script has a weird syntax because of its origins in the early days of computing and its evolution over time. While it may seem strange at first, once you familiarize yourself with it, you'll appreciate its efficiency and readability. So, the next time you come across the "case" statement in a bash or zsh script, you'll know the story behind its unique syntax.
