unfast: 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/unfast - from package: ladr4-apps

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

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