gnatpython-mainloop: 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/gnatpython-mainloop - from package: python-gnatpython

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

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