rpl8: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/rpl8 - from package: dvd+rw-tools

You may install the required package with command apt-get install {package}

Error in other languages:
rpl8: bevel nie gevind nie
rpl8: comandă negăsită
rpl8: comando não encontrado
rpl8: commande introuvable
rpl8: command not found
rpl8: käsku ei ole
rpl8: không tìm thấy lệnh
rpl8: komanda nerasta
rpl8: Kommando nicht gefunden.
rpl8: kommandot finns inte
rpl8: komut yok
rpl8: nie znaleziono polecenia
rpl8: níor aimsíodh an t-ordú
rpl8: no se encontró la orden
rpl8: no s'ha trobat l'ordre
rpl8: opdracht niet gevonden
rpl8: parancs nem található
rpl8: perintah tidak ditemukan
rpl8: príkaz nenájdený
rpl8: příkaz nenalezen
rpl8: команда не найдена
rpl8: командата не е открита
rpl8: 命令找不到
rpl8: コマンドが見つかりません