You can check the kernel information as well as a few other things using the uname command. Using just uname alone will usually just show you that you are using the Linux kernel.
[[email protected] ~]# uname
Linux
To see just the kernel release, you can use the -r flag.
[[email protected] ~]# uname -r
2.6.18-194.26.1.el5.028stab079.2
Then the -v to see the version of the kernel that you are using.
[[email protected] ~]# uname -v
#1 SMP Fri Dec 17 19:25:15 MSK 2010
To check the processor type, you use the -p flag
[[email protected] ~]# uname -p
x86_64
Then, you can check the operating system with the -o flag.
[[email protected] ~]# uname -o
GNU/Linux
Along with the hostname command, you can use uname to see your hostname.
[[email protected] ~]# uname -n
server
Finally, if you want to see all of this information at the same time, you can use the -a flag for all, which is the one that i use anytime i need to see this information.
[[email protected] ~]# uname -a
Linux server 2.6.18-194.26.1.el5.028stab079.2 #1 SMP Fri Dec 17 19:25:15 MSK 2010 x86_64 x86_64 x86_64 GNU/Linux
