grib_set: 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/grib_set - from package: grib_api

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

On Debian possible default full paths are:

/usr/bin/grib_set - from package: libgrib-api-tools

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

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