Shell Programming and Scripting

#!/usr/bin/bash
LIST=/tmp/list
while [[ "$c" != "2" ]]
do
    echo "1 - Enter a name
    2 - display $LIST
     3 - Exit"
    echo "Make your choice 1/2/3: "
    read c
    case $c in
    1)
        echo "Enter the name :"
        read a
        if ( ! grep ^"$a"$ $LIST >/dev/null 2>&1 )
        then
            echo "$a" >>$LIST
             echo "$a has been added to $LIST"
        else
            echo "filename $a already existing in $LIST, wanna remove it from list y/[n]?"
            read q
            case $q in
                 y|Y) grep -v ^"$a"$ $LIST >$LIST.tmp ; mv $LIST.tmp $LIST ; echo "$a removed from $LIST" ;;
                 n|N) echo "ok $a will stay in $LIST" ;;
                 *) echo "wrong choice, $LIST will stay as is" ;;
            esac
        fi
    ;;
    2) cat $LIST ;;
    3) exit 0 ;;
    *) echo "Wrong choice, try again..." ;;
    esac
done

remove_once(){
flag=0
while read a
do if [ "$a" = "$1" ]
        then
            if [ $flag -eq 0 ]
            then
                 echo "$a" >>$LIST.tmp
                 let flag++
            fi
        else
             echo "$a" >>$LIST.tmp
        fi
done <$LIST
mv $LIST.tmp $LIST
}