How to check for errors in RAM via linux?

By installing the memtester package, you can check your system for errors while it's still running. No need for a restart, just run that application.

To install it, open a terminal and type:

sudo apt-get install memtester

You can then use it like so:

sudo memtester 1024 5

This should allocate 1024MB of memory, and repeat the test 5 times.

The Ubuntu Live CD includes a tool called Memtest86+ that will do just that—test your computer’s RAM. Boot up from the Ubuntu LiveCD, press and hold the Shift key, which will bring up the GRUB menu. Select Memory Test

I have found mprime to be a good tool to test memory: ftp://mersenne.org/gimps/

(mprime can also be used to stress test your CPU)

Alternatively, use the package stress-ng to run all kind of stress tests (including memory test) on your machine.