drbl-sl: 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/sbin/drbl-sl - from package: drbl

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

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