How to use a case statement in Zsh

A shell script often needs to turn one short input into a defined action without scattering string tests across the file. A Zsh case statement keeps those choices together and stops at the first pattern that matches.

Each branch begins with a pattern followed by ) and ends with ;;. Zsh accepts a parenthesized pattern such as (prod|production), while the | separator lets either word select the same branch.

The target router keeps the selected URL in one variable and reserves exit status 2 for invalid input. A syntax check catches an unfinished branch before execution, a recognized alias prints its assigned URL, and the catch-all branch provides fail-capable proof for an unsupported target.

Steps to use a case statement in Zsh:

Create deploy-target.zsh with its interpreter, strict options, and first-argument input.
deploy-target.zsh
```
#!/usr/bin/env zsh
setopt ERR_EXIT NO_UNSET
 
target=${1:-}
```
The :- form leaves target empty when no first argument was supplied, and NO_UNSET still catches other accidental reads of undefined parameters.
Add the development and staging branches after the target assignment.
```
case $target in
    (dev|development)
        url=https://dev.example.com
        ;;
    (stage|staging)
        url=https://staging.example.com
        ;;
```
The opening parenthesis is valid Zsh case syntax. Each | pattern sends two accepted names to one assignment.

Add the production branch after the staging branch.

    (prod|production)
        url=https://www.example.com
        ;;

Close the case block with missing-target and catch-all guards.

    ("")
        print -u2 -- "missing target"
        exit 2
        ;;
    (*)
        print -u2 -- "unknown target: $target"
        exit 2
        ;;
esac

A leading * branch matches every target and prevents later specific branches from running.

Append the selected target and URL output after esac.

print -r -- "target=$target"
print -r -- "url=$url"

Check deploy-target.zsh for Zsh syntax errors.
```
$ zsh -n deploy-target.zsh
```
No output means Zsh parsed the completed case statement without finding a syntax error.

Run the shared prod|production branch with its short alias.

$ zsh deploy-target.zsh prod
target=prod
url=https://www.example.com

Run an unsupported target to exercise the catch-all branch.
```
$ zsh deploy-target.zsh sandbox
unknown target: sandbox
```
Print the catch-all command's exit status without running another command first.
```
$ printf 'exit=%s\n' "$?"
exit=2
```
A status of 2 distinguishes rejected input from a recognized branch, which returns 0. The shell replaces $? after any later command.