rmt: 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:

/sbin/rmt - from package: rmt

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

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