list_available_deb: 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/share/drbl/bin/list_available_deb - from package: drbl

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

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