What Linux distribution am I running?
Here is how you can find out when logged in through SSH:
uname -a
This generally won’t tell you as much as you’d like.
cat /proc/version
This will generally tell you more than you’d like.
Once you know that you are running Red Hat for example, you can get to the point with:
cat /etc/redhat-release
Or on Debian:
cat /etc/debian_version