mtd_debug: 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/sbin/mtd_debug - from package: mtd-utils

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

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