gnat-gps: 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/gnat-gps - from package: gnat-gps

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

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