rdf2ihx: 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/rdf2ihx - from package: nasm-rdoff

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

On Debian possible default full paths are:

/usr/bin/rdf2ihx - from package: nasm

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

Error in other languages:
rdf2ihx: bevel nie gevind nie
rdf2ihx: comandă negăsită
rdf2ihx: comando não encontrado
rdf2ihx: commande introuvable
rdf2ihx: command not found
rdf2ihx: käsku ei ole
rdf2ihx: không tìm thấy lệnh
rdf2ihx: komanda nerasta
rdf2ihx: Kommando nicht gefunden.
rdf2ihx: kommandot finns inte
rdf2ihx: komut yok
rdf2ihx: nie znaleziono polecenia
rdf2ihx: níor aimsíodh an t-ordú
rdf2ihx: no se encontró la orden
rdf2ihx: no s'ha trobat l'ordre
rdf2ihx: opdracht niet gevonden
rdf2ihx: parancs nem található
rdf2ihx: perintah tidak ditemukan
rdf2ihx: príkaz nenájdený
rdf2ihx: příkaz nenalezen
rdf2ihx: команда не найдена
rdf2ihx: командата не е открита
rdf2ihx: 命令找不到
rdf2ihx: コマンドが見つかりません