Switch case with fallthrough?

Solution 1:

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

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

Solution 2:

Recent bash versions allow fall-through by using ;& in stead of ;;: they also allow resuming the case checks by using ;;& there.

for n in 4 14 24 34
do
  echo -n "$n = "
  case "$n" in
   3? )
     echo -n thirty-
     ;;&   #resume (to find ?4 later )
   "24" )
     echo -n twenty-
     ;&   #fallthru
   "4" | [13]4)
     echo -n four 
     ;;&  # resume ( to find teen where needed )
   "14" )
     echo -n teen
  esac
  echo 
done

sample output

4 = four
14 = fourteen
24 = twenty-four
34 = thirty-four

Solution 3:

Do not use () behind function names in bash unless you like to define them.
use [23] in case to match 2 or 3
static string cases should be enclosed by '' instead of ""

If enclosed in "", the interpreter (needlessly) tries to expand possible variables in the value before matching.

case "$C" in
'1')
    do_this
    ;;
[23])
    do_what_you_are_supposed_to_do
    ;;
*)
    do_nothing
    ;;
esac

For case insensitive matching, you can use character classes (like [23]):

case "$C" in

# will match C='Abra' and C='abra'
[Aa]'bra')
    do_mysterious_things
    ;;

# will match all letter cases at any char like `abra`, `ABRA` or `AbRa`
[Aa][Bb][Rr][Aa])
    do_wild_mysterious_things
    ;;

esac

But abra didn't hit anytime because it will be matched by the first case.

If needed, you can omit ;; in the first case to continue testing for matches in following cases too. (;; jumps to esac)

Solution 4:

Try this:

case $VAR in
normal)
    echo "This doesn't do fallthrough"
    ;;
special)
    echo -n "This does "
    ;&
fallthrough)
    echo "fall-through"
    ;;
esac

Solution 5:

If the values are integer then you can use [2-3] or you can use [5,7,8] for non continuous values.

#!/bin/bash
while [ $# -gt 0 ];
do
    case $1 in
    1)
        echo "one"
        ;;
    [2-3])
        echo "two or three"
        ;;
    [4-6])
        echo "four to six"
        ;;
    [7,9])
        echo "seven or nine"
        ;;
    *)
        echo "others"
        ;;
    esac
    shift
done

If the values are string then you can use |.

#!/bin/bash
while [ $# -gt 0 ];
do
    case $1 in
    "one")
        echo "one"
        ;;
    "two" | "three")
        echo "two or three"
        ;;
    *)
        echo "others"
        ;;
    esac
    shift
done