secpanel: 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/secpanel - from package: secpanel

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

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