setregdomain: 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/sbin/setregdomain - from package: crda

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

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