prints out the differences of two strings (bash function)

gistfile1.txt

# prints out the differences of two strings
# @param string input1
# @param string input2

function strdiff()
{
    [ -z "$1" ] && return 1
    [ -z "$2" ] && return 1

    set -x
    mkfifo $$.fifo1 && mkfifo $$.fifo2
    if [ -e "$$.fifo1" ] && [ -e "$$.fifo2" ]; then 
        _strdiff_var_1st_string=$(printf "%s" "$1" | sed 's: :\n:g')
        _strdiff_var_2nd_string=$(printf "%s" "$2" | sed 's: :\n:g')
        printf "%s\\n" "$_strdiff_var_1st_string" > "$$.fifo1" &
        printf "%s\\n" "$_strdiff_var_2nd_string" > "$$.fifo2" &
        _strdiff_var_diff=$(awk 'NR == FNR { A[$0]=1; next } !A[$0]' "$$.fifo1" "$$.fifo2")
        rm -rf "$$.fifo1"; rm -rf "$$.fifo2"
        printf "%s\\n" "$_strdiff_var_diff"
    set +x
    else
        return 1
    fi
}