Centos

CentOS is basically the same thing as RedHat Enterprise, but free, right now it's on version 5, where it will be for years probably.

if you want to load up other packages than standard, you will mostly likely wander over to the Dag Wieers repository, which you can do by running this command:

 rpm -Uhv http://apt.sw.be/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm

or if you're running CentOS 4.4

 rpm -Uhv http://apt.sw.be/packages/rpmforge-release/rpmforge-release-0.3.6-1.el4.rf.i386.rpm

if that doesn't work, just download the package from here: http://dag.wieers.com/rpm/packages/rpmforge-release/ and then scp it over and run it
then you can run

 apt-get update
 apt-get upgrade

cat /etc/redhat-release	shows what version you're running
chkconfig --level 345 httpd on	apache will automatically start when rebooted
chkconfig --list	lists what starts up on boot
fuser -km /dev/cdrom	force unmounts your cdrom if umount /dev/cdrom doesn't work and says it's busy
less	find out what's installed on your system
rpm -qi httpd	tells you all about httpd that's installed
rpm -qf /usr/sbin/httpd	tells you what rpm that file belongs to
rpm -ql httpd	lists all the files httpd uses, nice for troubleshooting
rpm -q --whatprovides libapr-1.so.0	finds out what packages will install libapr-1.so.0
rpm -Uvh --test php-4.4.6-2.rs.rhel4.i386	does a test install to let you know if there are problems
service httpd start	starts apache, kind of like doing /etc/init.d/httpd start
32 1 * * * yum -y update > /var/log/messages	runs nightly yum update and logs the results to /var/log/messages
yum whatprovides libpam	searches yum repository for packages that include libpam library