radiusd: 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/radiusd - from package: freeradius

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

On Debian possible default full paths are:

/usr/sbin/radiusd - from package: radiusd-livingston

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

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