mmount: 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/mmount - from package: mtools

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

On Debian possible default full paths are:

/usr/bin/mmount - from package: mtools

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

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