ebnupgrade: 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/ebnupgrade - from package: ebnetd-common

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

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