uname

Identify Linux Kernel Version
Identify Redhat or SUSE Version

uname -r
2.4.21-32.0.1.EL

uname -a
Linux YOURHOSTNAME.COM 2.4.21-32.0.1.EL #1 Tue May 17 18:01:37 EDT 2005 i686 i686 i386 GNU/Linux