radlogin: 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/radlogin - 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/radlogin - from package: libfreeradius-client-dev

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

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