armada-backlight: 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/armada-backlight - from package: armada-backlight

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

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