gxtran: 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/gxtran - from package: grads

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

On Debian possible default full paths are:

/usr/bin/gxtran - from package: grads

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

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