mmass: 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/mmass - from package: mMass

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

On Debian possible default full paths are:

/usr/bin/mmass - from package: mMass

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

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