ReactiveNav3D-Demo: 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/ReactiveNav3D-Demo - from package: mrpt-apps

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

Error in other languages:
ReactiveNav3D-Demo: bevel nie gevind nie
ReactiveNav3D-Demo: comandă negăsită
ReactiveNav3D-Demo: comando não encontrado
ReactiveNav3D-Demo: commande introuvable
ReactiveNav3D-Demo: command not found
ReactiveNav3D-Demo: käsku ei ole
ReactiveNav3D-Demo: không tìm thấy lệnh
ReactiveNav3D-Demo: komanda nerasta
ReactiveNav3D-Demo: Kommando nicht gefunden.
ReactiveNav3D-Demo: kommandot finns inte
ReactiveNav3D-Demo: komut yok
ReactiveNav3D-Demo: nie znaleziono polecenia
ReactiveNav3D-Demo: níor aimsíodh an t-ordú
ReactiveNav3D-Demo: no se encontró la orden
ReactiveNav3D-Demo: no s'ha trobat l'ordre
ReactiveNav3D-Demo: opdracht niet gevonden
ReactiveNav3D-Demo: parancs nem található
ReactiveNav3D-Demo: perintah tidak ditemukan
ReactiveNav3D-Demo: príkaz nenájdený
ReactiveNav3D-Demo: příkaz nenalezen
ReactiveNav3D-Demo: команда не найдена
ReactiveNav3D-Demo: командата не е открита
ReactiveNav3D-Demo: 命令找不到
ReactiveNav3D-Demo: コマンドが見つかりません