I just want to install a minimal gnome desktop without all the thunderbird/firefox and any other packages that may come with full centos live cd. Is there something like yum groupinstall base-desktop? Ideally, I just want xorg-gnome and then add any other packages manually. No gdm also, I just want to run startx.
It includes the following packages:
It includes gdm which is arguably part of a basic desktop but does not include Firefox, Thunderbird, etc. If you still want less, you'll want to pick the packages out of the above list you want and do a yum install on the specific ones you for your desired desktop.
The stuff you are talking about won't amount to much on disk, maybe 1/2 GB or so at most. If your space is so that tight this is a concern, then you will need to find a minimal install sans X and build up from there. If you want to end up with anything involving GNOME at all though, this probably won't make much difference, and it is a hassle.
That said, I notice this remark here under "CentOS 6 Releases":
With regard to booting to console and using startx, this is just a matter of setting the default runlevel. CentOS still uses a SysV style init system. Look in
There are probably some comments that go with it. Change the 5 to a 3 and you will no longer boot straight into X.
Installing gnome without gdm will be impossible, but that does not mean you have to use it.