grace_period: 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/grace_period - from package: nfs-ganesha-utils

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

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