nbd-trdump: 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:

/bin/nbd-trdump - from package: nbd-server

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

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