Bash by Example: Case Statements

Bash 5.0+

Handling multiple conditions cleanly with case statements as an alternative to long if-elif chains, using pattern matching with wildcards and character classes, implementing default cases with the catch-all pattern, and organizing complex conditional flows with readable case syntax.

Code

#!/bin/bash

fruit="apple"

case "$fruit" in
    "apple")
        echo "It's an apple."
        ;;
    "banana" | "plantain")
        echo "It's a banana or plantain."
        ;;
    "cherry")
        echo "It's a cherry."
        ;;
    *)
        echo "Unknown fruit."
        ;;
esac

Explanation

The case statement is a powerful alternative to multiple if-elif-else blocks, especially when comparing a single variable against several possible values. It improves readability and makes the logic easier to follow. The syntax involves matching a variable against patterns, each terminated by a double semicolon ;;.

One of the key features of case is its support for pattern matching. You can use wildcards like * (matches anything) and ? (matches any single character), as well as character classes like [a-z]. You can also match multiple patterns for a single block using the pipe | symbol.

The case statement always ends with esac (case spelled backwards). It is common practice to include a "catch-all" pattern *) at the end to handle any values that didn't match previous patterns, acting like the else in an if-statement.

Code Breakdown

6

case "$fruit" in starts the statement. Quoting the variable is good practice to handle spaces or empty values safely.

7

"apple") is a pattern. If $fruit matches "apple", the commands following this line are executed.

10

The pipe | allows matching multiple patterns. This block runs if the fruit is either "banana" OR "plantain".

16

*) is the default case. It matches anything not matched by previous patterns. This is essential for error handling or default behavior.

Samplebadu

Bash by Example: Case Statements

Code

Explanation

Code Breakdown