xpdtest: 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/xpdtest - from package: root-proofd

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

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