i run the command " chmod -R 777 / " but after rebooting i cannot logged as root. when i login as ordinary user i cannot go to the x window, only in the console, how can i fixed this problem and how can i make the entire / directory permissions to default.... the distro i'm using is Fedora Core 2... pls help.

why make every single file executable?

I think you really messed it up.

it's easier to reinstall linux that recover from this.
Linux is not windowz!!!!!!!!
if you want to have full control of your system just always log-in as root which is NOT RECOMENDED.
respect the permissions!!!
use root only to configure or install something.

if u type
rm -fr /
as root the system will let you delete your whole read-write mounted paticions!!!(Linux is NOT WINDOwZ).
Better luck next time

hokagi_ninja - unfortunately, I would say there is no simple way to recover from the global "chmod 777" command without doing a reinstall.

Comments:

1. If you do reinstall, be sure to back up any important data you want to save from your /home directory.
2. As perfect_circle indicated, running as root is a very risky practice. You should only run as root when absolutely necessary (such as to install or upgrade software packages)
3. What problem were you trying to solve that prompted you to run the chmod 777 comnmand? -- J.W.

i use the knoppix live cd to change the permissions. i can now login as a root but still i cannot get to the x windows. Is there a way to change the permission of some file so that i can use the x windows?

You've made changes to your system that are not recoverable. J.W. has made a good suggestion with performing a reinstall to get back to a known state. The people that put together distributions make a lot of decisions about permissions and what goes into that distribution to make it work properly once installed. Using chmod like you did is rather reckless.

Now, lets look at your problem. It sounds like you were trying to get X windows up and running and thought that file permissions were the problem. Two things you should know, file permissions are rarely a problem on a new install. Secondly, when running as root permissions are essentially bypassed. Did you try executing the command startx at the command prompt? What happened? If that didn't work there is most likely a problem with the configuration of your xserver. Let us know what kind of a response your system gave and we can be more help.

You might also want to check out the file /etc/inittab to see if this was configured properly to boot into X windows. The line id:5:initdefault: should have a 5 after id:. If it has a 3 you will boot in command line or terminal mode.

Now, why did you boot up Knoppix to work on Fedora Core 2? Were you having login trouble with Fedora? If so you should use the boot disk you made during the install to boot the system in rescue mode. You can also boot from the CD to go into rescue mode. While it is possible to boot with Knoppix I feel it is better to work on your system with tools from the same distribution. Let us know how things go. I'm sure there are people here that can help.

Bill