mclasserase: 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/mclasserase - from package: mtools

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

On Debian possible default full paths are:

/usr/bin/mclasserase - from package: mtools

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

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