Bash – Switch case with fallthrough

bashswitch statement

I am looking for the correct syntax of the switch statement with fallthrough cases in Bash (ideally case-insensitive).
In PHP I would program it like:

switch($c) {
    case 1:
        do_this();
        break;
     case 2:
     case 3:
        do_what_you_are_supposed_to_do();
        break;
     default:
        do_nothing(); 
}

I want the same in Bash:

case "$C" in
    "1")
        do_this()
        ;;
    "2")
    "3")
        do_what_you_are_supposed_to_do()
        ;;
    *)
        do_nothing();
        ;; 
esac

This somehow doesn't work: function do_what_you_are_supposed_to_do() should be fired when $C is 2 OR 3.

Best Answer

Use a vertical bar (|) for "or".

case "$C" in
"1")
    do_this()
    ;;
"2" | "3")
    do_what_you_are_supposed_to_do()
    ;;
*)
    do_nothing()
    ;;
esac

Related Solutions

Python – Replacements for switch statement in Python

The original answer below was written in 2008. Since then, Python 3.10 (2021) introduced the match-case statement which provides a first-class implementation of a "switch" for Python. For example:

def f(x):
    match x:
        case 'a':
            return 1
        case 'b':
            return 2
        case _:        
            return 0   # 0 is the default case if x is not found

The match-case statement is considerably more powerful than this simple example.

You could use a dictionary:

def f(x):
    return {
        'a': 1,
        'b': 2,
    }[x]

C++ – Why can’t variables be declared in a switch statement

Case statements are only labels. This means the compiler will interpret this as a jump directly to the label. In C++, the problem here is one of scope. Your curly brackets define the scope as everything inside the switch statement. This means that you are left with a scope where a jump will be performed further into the code skipping the initialization.

The correct way to handle this is to define a scope specific to that case statement and define your variable within it:

switch (val)
{   
case VAL:  
{
  // This will work
  int newVal = 42;  
  break;
}
case ANOTHER_VAL:  
...
break;
}

Best Answer

Related Solutions

Python – Replacements for switch statement in Python

C++ – Why can’t variables be declared in a switch statement

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