radiusclient: 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/radiusclient - from package: radiusclient-ng-utils

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

On Debian possible default full paths are:

/usr/sbin/radiusclient - from package: libfreeradius-client-dev

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

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