gfal_testrw: 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/gfal_testrw - from package: gfal-doc

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

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