nrefactory-demo-gtk: 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/nrefactory-demo-gtk - from package: nrefactory-samples

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

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