muffin-message: 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/muffin-message - from package: muffin

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

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