photon: 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/photon - from package: photon

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

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