gribscan: 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/gribscan - from package: grads

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

On Debian possible default full paths are:

/usr/bin/gribscan - from package: grads

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

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