mlhead: 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/mlhead - from package: svtools

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

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