mtt: 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/mtt - from package: xawtv-mtt

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

On Debian possible default full paths are:

/usr/bin/mtt - from package: xawtv

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

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