rlmgr: 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 Debian possible default full paths are:

/usr/bin/rlmgr - from package: qdbm-util

You may install the required package with command apt-get install {package}

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