mpack: 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/mpack - from package: mpack

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

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