rdfdump: 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/rdfdump - from package: nasm-rdoff

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

On Debian possible default full paths are:

/usr/bin/rdfdump - from package: nasm

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

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