cpdup: 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/cpdup - from package: cpdup

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

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