if ($command eq "add") {
 ....
} elseif ($command eq "view") {
 ....
} elseif ($command eq "something") {
 ....
} elseif ( ... ) {
 ....
} elseif ( ... ) {
 ....
} elseif ( ... ) {
 ....
} elseif ( ... ) {
 ....
} elseif ( ... ) {
 ....
} elseif ( ... ) {
 ....
.
.
.
.
}

##</code><code>##

%menus = (
   'first' => { 
                'add' => '&add',
                'view' => '&view',
                'a' => '\$menus{first}{add}',
                'v' => '\$menus{first}{view}',
              },
   'second' => {
                'delete' => '&delete',
                'print' => '&print',
               },
);

##</code><code>##

$menus{first}{$_} if exists $menus{first}{$_};

or

print "Command not found.\n" if not exists $menus{first}{$_};