gfal-xattr: command not found

Have You tried accessing the binary with the full path?

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-xattr - from package: gfal2-util

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