rdfproc: 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/rdfproc - from package: redland

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

On Debian possible default full paths are:

/usr/bin/rdfproc - from package: redland-utils

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

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