mt: 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:

/bin/mt - from package: mt-st

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

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