mln: command not found

Have You tried accessing the binary with the full path?

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/mln - from package: mmv

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