aubusy: 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/aubusy - from package: aufs-tools

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

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