hpanel: 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/hpanel - from package: hpanel

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

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