grib_compare: 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_compare - 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_compare - from package: libgrib-api-tools

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

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