rdf2srec: 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/rdf2srec - from package: nasm-rdoff

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

On Debian possible default full paths are:

/usr/bin/rdf2srec - from package: nasm

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

Error in other languages:
rdf2srec: bevel nie gevind nie
rdf2srec: comandă negăsită
rdf2srec: comando não encontrado
rdf2srec: commande introuvable
rdf2srec: command not found
rdf2srec: käsku ei ole
rdf2srec: không tìm thấy lệnh
rdf2srec: komanda nerasta
rdf2srec: Kommando nicht gefunden.
rdf2srec: kommandot finns inte
rdf2srec: komut yok
rdf2srec: nie znaleziono polecenia
rdf2srec: níor aimsíodh an t-ordú
rdf2srec: no se encontró la orden
rdf2srec: no s'ha trobat l'ordre
rdf2srec: opdracht niet gevonden
rdf2srec: parancs nem található
rdf2srec: perintah tidak ditemukan
rdf2srec: príkaz nenájdený
rdf2srec: příkaz nenalezen
rdf2srec: команда не найдена
rdf2srec: командата не е открита
rdf2srec: 命令找不到
rdf2srec: コマンドが見つかりません