aa-status: 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/sbin/aa-status - from package: apparmor

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

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