dibbler-requestor: 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/dibbler-requestor - from package: dibbler-requestor

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

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