mt-dds: 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/mt-dds - from package: dds2tar

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

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