Initial Setup of a Linux CentOS5 / RHEL5 System

Running Linux straight out of the box is a bit of a raw experience. I make a number of tweaks after the initial install. I'm going to document these tweaks here.

Never login as root!

During the install, there will be a place to create an account. Create an account there. Login with the account you created during the install.

Get sudo working for your account.

Once you are logged in, start a "Terminal". Type su, type the root password. This will be the first and last time you type "su". Now, edit /etc/sudoers. Find the line

## Allow root to run any commands anywhere
root    ALL=(ALL)       ALL

and add you account:

## Allow root to run any commands anywhere
root    ALL=(ALL)       ALL
jkh     ALL=(ALL) NOPASSWD:     ALL

I add the "NOPASSWD:" option, this allows you to run sudo with out typing your password. Many people would argue that this is a security problem. Just make sure that your password is strong.

## Allow root to run any commands anywhere
root    ALL=(ALL)       ALL
jkh     ALL=(ALL) NOPASSWD:     ALL

Since the /etc/sudoers is not "write-able" by anyone, to save the file you must use ":w!" followed by ":q". Now exit "su" with "Ctrl-D".

Get things up-to-date.

Apply all updates since the CD/DVD was burned.

sudo yum -y update

Add yum repositories.

There are three yum repositories I add: epel (Extra Packages for Enterprise Linux), Dag Wieers' excellent rpmforge, and for Adobe's flash and pdf. Its a bit tricky to do this properly, the yum repos will step on each-others' feet. Largely I follow this.

1. First install yum-priorities as suggested.
   1. Edit /etc/yum/pluginconf.d/priorities.conf and verify that it is on.
   2. Edit /etc/yum.repos.d/CentOS-Base.repo, add priority=1 for each section.
2. Install epel.
   1. There should be a more automatic, cut-n-paste of this. But, something like

sudo rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-2.noarch.rpm

Where i386 is your machine architecture. This may be x86_64 for 64 bit installs. And the 5-2 release number may not be correct as the releases march along with time.

1. 1. Edit /etc/yum.repos.d/epel.repo, add priority=3 to each section

Now, edit /etc/yum.repos.d/epel.repo and add priority=2 for each section.