nvtv: 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/nvtv - from package: nvtv

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

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