Q:

hwclock can't open rtc file

I am trying to control my raspberry pi using ssh in a Windows computer DHCP. 
When I try to login with root in my computer it says access denied, so I created a user and tried to login with it from my computer but it says your password has expired change password and login again. 
I think it's because my hardware date is set to Jan 1970. So I tried changing the date using the date command and it only changes the system's date. Whenever I try hwclock -w its says hwclock : can't open /dev/misc/rtc : no such file or directory 
I listed my /dev/ folders there is not rtc and no misc. I tried to show the logs using dmesg to figure out the file the system uses to get date in boot but I couldn't find anything. 
What can I do to find out which file ?  Does anyone know why I'm getting the password expired error?

A:

The raspberry is a low cost PC/iOT and does not have an RTC by default.
You either set time via NPT in an Internet connected rpi, and/or buy an RTC clock like the DS3231 that costs around 1.25€ in Aliexpress or around £9  in an uk site.
Upon connecting it to the rpi bus, you will be able to use the RTC in Linux after booting. 
PS. Be sure to connect it while the rpi is off.

