drbl-userdel-list: 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-userdel-list - from package: drbl

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

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