mpartition: 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 CentOS possible default full paths are:

/usr/bin/mpartition - from package: mtools

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/mpartition - from package: mtools

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

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