nrss: 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/nrss - from package: nrss

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

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