normal3d: 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/normal3d - from package: raster3d

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

Error in other languages:
normal3d: bevel nie gevind nie
normal3d: comandă negăsită
normal3d: comando não encontrado
normal3d: commande introuvable
normal3d: command not found
normal3d: käsku ei ole
normal3d: không tìm thấy lệnh
normal3d: komanda nerasta
normal3d: Kommando nicht gefunden.
normal3d: kommandot finns inte
normal3d: komut yok
normal3d: nie znaleziono polecenia
normal3d: níor aimsíodh an t-ordú
normal3d: no se encontró la orden
normal3d: no s'ha trobat l'ordre
normal3d: opdracht niet gevonden
normal3d: parancs nem található
normal3d: perintah tidak ditemukan
normal3d: príkaz nenájdený
normal3d: příkaz nenalezen
normal3d: команда не найдена
normal3d: командата не е открита
normal3d: 命令找不到
normal3d: コマンドが見つかりません