rddi: 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/rddi - from package: rdd

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

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