radeontool: 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 Debian possible default full paths are:

/usr/sbin/radeontool - from package: radeontool

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

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