rtc: 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/rtc - from package: nvram-wakeup

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

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