decnetconf: 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/decnetconf - from package: dnet-common

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

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