Torn from the pages of “This is so simple I forget it even after doing it a hundred times.”

UPDATE (because I’m a noob):

As is shown in the comments by Scott Pack and Kenny Rasschaert, my hacktastic way of finding a CentOS machine’s specific release isn’t the best way to do things. It’s best to check the release package:

rpm -qa | grep release

Of course, as Chris S of ServerFault fame points out below, uname -a is useful as well. It shows the build number of your OS, which might not be quite as easy to read as searching your rpms. An example from my laptop:

uname -a
Linux Fedora1530 2.6.35.14-106.fc14.i686.PAE #1 SMP Wed Nov 23 13:39:51 UTC 2011 i686 i686 i386 GNU/Linux

One thing to note from Scott of the Pack clan (Information Security Expert of Renowned): “one of the first things I do during an investigation is try to figure out what distro I’m looking at. I usually check out /etc/issue, /etc/*release*, the package name, and uname. Mostly just to figure out if they all agree.” Thanks Scott!

My original, ignoble method of finding my CentOS version was this:

cat /etc/redhat-release

However, some will contend that this method is not foolproof and that some RedHat based distributions change the release file’s name. A more robust method is as follows:

cat /etc/*release*