grok-pull: 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/bin/grok-pull - from package: python-grokmirror

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

On Debian possible default full paths are:

/usr/bin/grok-pull - from package: grokmirror

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

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