RGrid: 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/RGrid - from package: vtk-examples

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

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