Shell Programming and Scripting

      case "$FUN" in
          1\ *) do_change_pass ;;
          2\ *) do_network_menu ;;
          3\ *) do_boot_menu ;;
          4\ *) do_internationalisation_menu ;;
          5\ *) do_ssh ;;
          6\ *) do_pixdub ;;
          8\ *) do_update ;;
          9\ *) do_about ;;
          *) whiptail --msgbox "Programmer error: unrecognized option" 20 60 1 $
        esac || 

GET CASE RETURN VALUE HERE 

whiptail --msgbox "There was an error running option $FUN" 20 6$
      fi

       case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
              A case command first expands word, and tries to match it against each pattern in turn, using the same matching rules as  for  path‐
              name  expansion  (see  Pathname  Expansion  below).   The word is expanded using tilde expansion, parameter and variable expansion,
              arithmetic expansion, command substitution, process substitution and quote removal.  Each pattern examined is expanded using  tilde
              expansion,  parameter and variable expansion, arithmetic expansion, command substitution, and process substitution.  If the nocase‐
              match shell option is enabled, the match is performed without regard to the case of alphabetic characters.  When a match is  found,
              the corresponding list is executed.  If the ;; operator is used, no subsequent matches are attempted after the first pattern match.
              Using ;& in place of ;; causes execution to continue with the list associated with the next set of patterns.  Using ;;& in place of
              ;;  causes the shell to test the next pattern list in the statement, if any, and execute any associated list on a successful match.
              The exit status is zero if no pattern matches.  Otherwise, it is the exit status of the last command executed in list.

case
....
esac
if [ "${?}" -ne 0 ]; then
   echo NONzero
else
   echo zero
fi