I am runnin CentOS 5.4 on a machine wiht 2GB of ram. of that 2GB free -m shows that 1.8 is being used. I wanted to find out what was consumign the RAM. I came across .mozilla folder in every users home directory. I am thinkning, is this machine some kind of GUI that is consuming the ram?

I did ps aux | grep gnome and ps aux | grep kde but that came up with nothing.

rpm -qa | grep gnome showed lots of gnome python RPM's.

I am using ssh to connect to the machine and can not log in locally to see since it is at a remote location. Is there any way of finding out if a GUI is running, if so how would I uninstall it?

Use top or htop to show you what's actually using the RAM in real time.

To answer your subject line, no. A .mozilla folder in home directories does not mean any mozilla process is running, only that a mozilla application is installed and set up.

So are you sitting at this machine, or is this a remote server? Assuming the latter, since you would be able to easily see if a GUI is running on a local machine...

Running the command 'runlevel' might help. If the result is '5' you are probably running an X login, '3' it is probably in multi-user text mode, though a user can still run an X session. These numbers may be different for different distros though.

use following command to know what process is using the max ram:

ps -A -e -o pid,ppid,rss,args --sort=rss

Process consuming most of the ram will be in the last (third coloumn)

Note: rss does not tell the exact size of RAM used by a process (coz it does not include stack data in the process), but still it helps in getting the idea.