What to do if a system component crashes?

[unni]

Hi,
Eventhough the need for this hasn't occured except may be once, I would like to know what to do if one of the following component crashes so that I can resume work without rebooting the pc. Also, please mention how to kill that component so that I can restart it again.

1. KDE
2. GNOME
3. X
4. Sound
5. Network (I am using ADSL)
6. Firewall
7. Keyboard & Mouse
8. Force a system wide refresh/update so that new settings will get reflected (both in KDE & GNOME)
9. Force a hardware re-detection

I know that a few of them can be achieved by "service name restart". But I am not confident of using them until I hear it from you guys:D. Also, if you know any other component, please mention them also. I want to ensure a reboot free life:p.

[mehulved]

1. KDE
2. GNOME
3. X
ctrl + alt + bkspace

4. Sound
never seen that happen.

5. Network (I am using ADSL)
no clue as I haven't used these types of connections

6. Firewall If I am not wrong iptables is built into kernel so no way it can fail unless it's a problem with kernel. But, would like to know more on this one.

7. Keyboard & Mouse


8. Force a system wide refresh/update so that new settings will get reflected (both in KDE & GNOME)
Isn't it applied instantaneously or just by logging out and logging back in?

9. Force a hardware re-detection
Why? New hardware is monitored for all the time.

I know that a few of them can be achieved by "service name restart". this is only for FC not for linux in general.

[freebird]

for refreshing the X use xrefresh -white command.
and u know that most of the services can be restarted..
For GNOME,it got a gnome-panel applet "force-quit" just add it to the panel and press it and press the failing gui app for killing the app sudden.
Redhat fedora uses lokkit for cofiguring iptables,even ubuntu debian too.u can set it easy.
For HW detection,kudzu for RH based distros and " discover --enable-all" for Debian based distros.
For sound u can restart alsa,use alsactl -d store to save volume control.
keyboard and mouse?

[unni]

Does Ctrl+Alt+Backspace restart X? While testing different settings in some games, if the game crashes, desktop won't regain its native 1024x768 resolution. In such situations, the only method I know is to reboot.

never seen that happen. After installing Kubuntu, I had to change my default sound card from the onboard one to the PCI one. For that I had to edit a file, after which if I knew how to restart sound system, I could have avoided a restart.
If I am not wrong iptables is built into kernel so no way it can fail unless it's a problem with kernel. But, would like to know more on this one. What I was actually thinking was to enforce a firewall policy change. Now I understand that Guarddog and Firestarter can do it easily.

for refreshing the X use xrefresh -white command.
For GNOME,it got a gnome-panel applet "force-quit" just add it to the panel and press it and press the failing gui app for killing the app sudden.
For sound u can restart alsa,use alsactl -d store to save volume control.
Doesn't xkill do the same as force-quit?
Did you mean "alsactl restore" when you typed alsactl -d? I haven't tried any of these yet.

About the keyboard redetection: I have been experiencing a strange problem with my Kubuntu for the past 3 days. While I am typing something, suddenly, the keyboard response becomes too slow. For example, if earlier the key repetition rate was 5 characters per second, now it becomes 1 per 10 second. I experienced this problem only when I am posting something here using Firefox. At first I thought it was because of my Microsoft USB keyboard. So I attached my PS2 keyboard also. But still the problem occurs. Reconnecting to another port won't help either. In the past 3 days, it has happened 7 times. Once it happens, I have to reboot. Everything else including mouse functions normally. So, I was thinking if I could make Kubuntu redetect the keyboard, may be I could avoid a reboot. (I was actually thinking about posting this as a different thread soon, after testing in Mandriva.)

Anyway, thank you guys for replying so soon. Sorry for the delay from my part. I was looking for the remaining methods.

[eddie]

Install htop from your software manager and keep it running in a terminal window. Now, when this keyboard sluggishness happens, look at htop window and see whether your CPU usage is very high or not. If it is...look which application is eating away the CPU cycles. I have seen this happen with Beagle running on my Gentoo system. Since then I keep beagle disabled.