I modify the file " /etc/sysconfig/network-scripts/ifcfg-eth0" to add the ip address to the entry "IPADDR" , and reboot the linux server , but i run ifconfig , it still show my ip is 127.0.0.1 , why will this happen , what is wrong in my setting ? thx ( RH8)

what file need to be modify to change the ip address ? thx

well first of all you don't need to reboot to change your IP adress, simply enter
[root@hostname root]# /etc/init.d/network restart
as root of course, should be adequate, the os is designed to not need alot of rebooting, in fact the only reasons i can think of for rebooting are upgrading the kernel, the hardware, or crashing, but , i digress...
as for 127.0.0.1, are you looking under the ifconfig entry for eth0 or lo, 127.0.0.1 is NEVER going to change, it's the generic localhost ip for interface lo, also try pinging the ip you think your machine is and see what happens

I know Red Hat has the tool /usr/sbin/netconfig which is useful for changing an IP address, but I've read that this doesn't "change the IP address everywhere it needs to." Is this true? I'm familiar with the /etc/sysconfig/network... files, but if I want to make sure my IP is changed everywhere, what file(s) or program(s) do I need to look into?

Thanks!

as far as i know simply edit
/etc/sysconfig/network-scripts/ifcfg-eth0
with your new ip addr, and then run
/etc/init.d/network restart
that worked for me