mrepo: 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/mrepo - from package: mrepo

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

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