aupanel: 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 CentOS possible default full paths are:

/usr/bin/aupanel - from package: nas

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/aupanel - from package: nas-bin

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

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