rfiod: 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/sbin/rfiod - from package: dpm-rfio-server

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

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