mlterm: 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:

/usr/bin/mlterm - from package: mlterm-tiny
/usr/bin/mlterm - from package: mlterm

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

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