case Command in Linux: Compare Values and Create Menus

The case command in Linux is a smart way to compare a value against multiple patterns.

If a match is found, it allows executing commands.

Each case is an expression that matches a pattern.

The operator ")" ends a pattern list and starts a command list.

What separates one pattern from another is ";;".

At the end of the case, you must end with the esac statement (case backwards).

Example of a script that prints a different message depending on the user's UID:

#!/bin/bashID=$(id -u)case "$ID" in   0)      echo "Você é o root.";      echo "Parabens!"   ;;   1000)      echo "Você é o Uirá."   ;;   100[1-9])      echo "Vocé é outro usuário"esacecho "fim";

If the value of variable ID is 0, it will print a congratulations message. If it equals 1000, it prints "you are Uirá". If it's between 1001 and 1009, it prints "You are another user".

If executed with user uira, who has UID equal to 1000:

$ ./meucase Você é o Uirá.fim

If executed as root:

$ sudo ./meucase Você é o root.Parabens!fim

The case is better than using the "if" command multiple times to compare something against multiple patterns.

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