nrg2iso: 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/nrg2iso - from package: nrg2iso

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

Error in other languages:
nrg2iso: bevel nie gevind nie
nrg2iso: comandă negăsită
nrg2iso: comando não encontrado
nrg2iso: commande introuvable
nrg2iso: command not found
nrg2iso: käsku ei ole
nrg2iso: không tìm thấy lệnh
nrg2iso: komanda nerasta
nrg2iso: Kommando nicht gefunden.
nrg2iso: kommandot finns inte
nrg2iso: komut yok
nrg2iso: nie znaleziono polecenia
nrg2iso: níor aimsíodh an t-ordú
nrg2iso: no se encontró la orden
nrg2iso: no s'ha trobat l'ordre
nrg2iso: opdracht niet gevonden
nrg2iso: parancs nem található
nrg2iso: perintah tidak ditemukan
nrg2iso: príkaz nenájdený
nrg2iso: příkaz nenalezen
nrg2iso: команда не найдена
nrg2iso: командата не е открита
nrg2iso: 命令找不到
nrg2iso: コマンドが見つかりません