auibusy: 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:

/sbin/auibusy - from package: aufs-tools

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

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