frm_admin: 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_admin - from package: xrootd-server

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

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