rpmextra: 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/rpmextra - from package: rpmorphan

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

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