grok-fsck: 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-fsck - 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-fsck - from package: grokmirror

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

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