07. Case statements case, esac

In some cases, a case statement can be more appropriate. For example, when you have a variable and need to execute lines of code depending on its value, the case statement makes for clean code.

Case statements do not execute any test commands and therefore do not use exit codes.

Sample script - Hello!

Here's a script that outputs a greetings depending on which country a user is from.

#!/bin/sh
 
echo "Please select which country you are from: "
 
printf "1: Canada
2: Croatia
3: Czech Republic
4: France
5: Germany
6: Greece
7: Italy
8: Netherlands
9: Poland
10: Sweden
11: United States
"
 
read -p "Country number code: " input
 
case $input in
  1|11) 
    echo 'Hello!'
    ;;
  2) 
    echo 'Bog!'
    ;;
  3) 
    echo 'Ahoj!'
    ;;
  4) 
    echo 'Salut!'
    ;;
  5|8) 
    echo 'Hallo!'
    ;;
  6) 
    echo 'YAH sahs!'
    ;;
  7) 
    echo 'Ciao!'
    ;;
  9) 
    echo 'Czesc!'
    ;;
  10)
    echo 'Hej!'
    ;;
  *)
    echo 'Please enter a valid number.'
    ;;
esac

Notice the use of the | operand. We may also use regular expressions if we are trying to match a string!

We may simplify this script with the select command, which we'll see next.

Sample Script 2 - with Regular Expressions

We can also use case-statements and match input strings with regular expressions!

Let's try to build a script where the user inputs his/her name, and the response changes depending on whether the input starts with a vowel or consonant.

#!/bin/sh
 
printf "What is your first name? "
read first_name
 
case $first_name in
    [aeiouAEIOU]*)
        echo 'Your name starts with a vowel!'
        ;;
    [0-9]*)
        echo 'Strange that your name would start with a number...'
        ;;
    [a-zA-Z]*)
        echo 'Your name starts with a consonant!'
        ;;
    *)
        echo 'Your name starts with some funky punctuation.'
        ;;
esac

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