xrdcp: 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/xrdcp - from package: xrootd-client

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

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