pyro-nsd: 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/pyro-nsd - from package: pyro

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

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