di-netboot-assistant: 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/bin/di-netboot-assistant - from package: di-netboot-assistant

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

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