nvassemble: 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/nvassemble - from package: libnvtt-bin

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

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