How do I tell what flavor/brand linux I am running?

There's no direct answer, but several manufacturers will store this information in particular files. Check and read the contents of these files:

  /etc/redhat-release
  /etc/debian_version
  /etc/lsb-release

If not found there, occasionally there is detailed info in proc:

  /proc/version

Another clue point is that many distros also put information on the various login banner files:

  /etc/issue
  /etc/issue.net
  /etc/motd

If none of these check out you may be running a very interesting distribution of linux. Check to see if there is any branding in the boot log and dmesg:

  /var/log/boot.log
  /var/log/dmesg

If there are no discernible boot logs, remember to check the output of the "dmesg" as a substitute.

If none of the above work, then your final detective work is the output of "uname -a"

"uname -a" won't give you the brand on most linuxes, but the specific kernel version, sub version and any patch flags in the name might turn something up in a search engine.