ng-nailgun: 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/ng-nailgun - from package: nailgun

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

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