Exit a bash switch statement

Question

I've written a menu driven bash script that uses a switch case inside of a while loop to perform the various menu options. Everything works just fine. Now I'm trying to improve the program by performing error testing on the user input, but I cannot seem to make it work...

The problem is I don't know how to properly break out of a switch statement, without breaking out of the while loop (so the user can try again).

# repeat command line indefinitely until user quits
while [ "$done" != "true" ]
do
   # display menu options to user
   echo "Command Menu" # I cut out the menu options for brevity....

   # prompt user to enter command
   echo "Please select a letter:"
   read option

   # switch case for menu commands, accept both upper and lower case
   case "$option" in

   # sample case statement
   a|A) echo "Choose a month"
        read monthVal
        if [ "$monthVal" -lt 13 ]
        then 
           cal "$monthVal"
        else
           break # THIS DOES NOT WORK. BREAKS WHILE LOOP, NOT SWITCH!
        fi
        ;;
   q|Q) done="true" #ends while loop
        ;;
   *)   echo "Invalid option, choose again..."
        ;;
   esac
done
exit 0

The program works fine when the user enters a valid month value, but if they enter a number higher than 13, instead of breaking the switch statement and repeating the loop again, the program breaks both the switch and while loop and stops running.

Answer 1

This should do the trick: Wrap the code in a one-trip for-loop:

#! /bin/bash

case foo in
  bar)
    echo "Should never get here."
    ;;

  foo)
    for just in this_once ; do
      echo "Top half only."
      if ! test foo = bar; then break; fi
      echo "Bottom half -- should never get here."
    done
    ;;

  *)
    echo "Should never get here either."
    ;;
esac

Answer 2

I think what you mean to do with break is "quit this case statement and restart the while loop". However, case ... esac isn't a control-flow statement (although it may smell like one), and doesn't pay attention to break.

Try changing break into continue, which will send control back to the start of the while loop.