samba_spnupdate: 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/samba_spnupdate - from package: samba

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

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