mt-st: 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 Debian possible default full paths are:

/bin/mt-st - from package: mt-st

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

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