sunxi-fel: 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/sunxi-fel - from package: sunxi-tools

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

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