reglookup: 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/reglookup - from package: reglookup

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

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