frm_xfragent: 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/frm_xfragent - from package: xrootd-server

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

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