If you do your initial Centos 6 install using “minimal install” from the full DVD or you use CentOS-6.0 minimal.iso you won’t have a desktop environment or other packages.

Thankfully the minimal install includes yum so you can add and remove packages from your system.  To install the Gnome desktop environment do one of the following as a root user:

yum groupinstall basic-desktop desktop-platform x11 fonts
yum groupinstall "Desktop" "Desktop Platform" "X Window System" "Fonts"

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Here is what is included in the minimal CentOS 6 install (taken from here):


http://wiki.centos.org/Manuals/ReleaseNotes/CentOSMinimalCD6.0






aic94xx-firmware
bfa-firmware
ql2100-firmware
ql2200-firmware
ql23xx-firmware
ql2400-firmware
ql2500-firmware
acl




attr
audit
binutils
checkpolicy
chkconfig
coreutils
curl
bridge-utils




db4-utils
device-mapper
dhclient
diffutils
dracut
e2fsprogs
efibootmgr
ethtool




findutils
fipscheck
gpgme
iproute
iptables
iputils
logrotate
lvm2




mdadm
mingetty
ncurses
net-tools
nfs-utils
nss-util
openssh-clients
openssh-server




python
rsyslog
selinux-policy-targeted
util-linux-ng
vi
yum