To check the version date of your OS (Linux distros):

uname -v

To find out the release:

uname -r

To display and show the complete kernel signature of your hosting server:

uname -a

Something like this will output similar information concerning your Linux kernel:

cat /proc/version

If you haven’t had the uname utility installed, you can get the kernel release version by:

cat /proc/sys/kernel/osrelease

You may also be interested in some other useful things to see within /proc.