Can I restart the KDE Plasma Desktop without logging out?

In KDE 4, you can do:

killall plasma-desktop #to stop it
kstart plasma-desktop #to restart it

In KDE 5 use:

killall plasmashell #to stop it
kstart plasmashell #to restart it

In KDE > 5.10 use:

kquitapp5 plasmashell
kstart5 plasmashell

Sometimes plasmashell is not responding so kquitapp5 fails after a timeout and you have to get back to killall. So in a nutshell, I would do :

# For KDE 4
killall plasma-desktop && kstart plasma-desktop

# For KDE 5 < 5.10
killall plasmashell && kstart plasma-desktop

# For KDE > 5.10
kquitapp5 plasmashell || killall plasmashell && kstart5 plasmashell

Remarks :

1. If you are not sure which KDE version your run, kinfocenter --version will tell you.
2. you can skip the kquitapp5 plasmashell || part if you don't want to be stuck in the timeout when plasmashell is not responding.

In KDE5 use "kstart plasmashell" to restart the plasmashell as a service instead of plasmashell &. If you use it that way it 's run as an independed service not connected to the current terminal session (meaning you can close the terminal without the process getting terminated). TLDR:

KDE5 (in Terminal):

killall plasmashell
kstart plasmashell

Well I didn't expect this to work (and it's not exactly what the question asks for) but pressing Alt+F2 and running:

kwin --replace

This reloads KDE's compositor and that seems to fix the flickering. I guess it's a factor into my particular issue.

The window manager kwin is responsible for moving around windows, etc. That can be restarted by this:

kstart kwin --replace

The kstart prefix is just to not run it as a subprocess in the current terminal, such that you can close the terminal afterwards.

plasmashell is responsible for the background and other shell things. Restarting that should work like this:

killall plasmashell
kstart plasmashell

Note that this did not bring back the menu for me.

Also, interestingly, this again breaks kwin for me, i.e. I'm not able to move windows around anymore. On console, I get sth like QXcbConnection: XCB error: 3 (BadWindow), sequence: ..., resource id: ..., major code: 15 (QueryTree), minor code: 0.

I looked this up because I had an issue where I couldn't open any KDE settings menus, but I didn't really want to reboot or log out. I found that the best way to do it (in KDE 5 at least) is by using krunner (Alt+F2) to killall plasmashell then immediately afterwards, plasmashell. I tried doing it in a Konsole window, using killall plasmashell and then plasmashell & and this worked, but as soon as I closed the Konsole window, plasma would close as well. Even though you seemed to resolve your issue, I figured I would post it for people coming along in the future needing to restart plasma.

In KDE 4, just replace plasmashell with plasma-desktop

I find I'm always having trouble with ksycoca5, and this seems to be the reason plasmashell gets in a strop, and also stops plasmashell restarting. To solve this I did:

$ mv ~/.cache/ksycoca5* /tmp
$ killall plasmashell buildksycoca5; kstart plasmashell

OK .. I am running OpenSuse Leap 15.1 running KDE5 Plasma. Periodically, my X environment is corrupted (after about 24 hours of leaving my machine running) and I get "KLauncher could not be reached via D-Bus. Error when calling start_service_by_desktop_path: Not connected to D-Bus server"

The result of this is that while my desktop still functions I can't launch any applications which use KLauncher -- very annoying. (NOTE: also my xwindows vncserver appears to launch 99 instances of display windows I could attach to -- which isnt right -- I havent corrected this yet but I will). However, I FOUND the answer to the above issue to restart KDE 5 Plasma in my environment without a reboot:

1) killall plasmashell 2) kstart5 plasmashell kwin

This restarts everything as if the system is freshly booted. Hope this helps

Thanks

In KDE4 I find the memory usage ramps up to around a gigglebite pretty rapidly because opening programs progressively uses more RAM, but closing them does not release it. This is in Mint 17.3 with KDE but seems to affect pretty well ALL KDE plasma 4 systems.

I got sick of logging in and out, or using ALT + F2 to kill and restart plasma. So now I just have a script (set as executable) sitting on the panel..

   
#!/bin/bash 
killall plasma-desktop 
plasma-desktop & 
   

Click on the icon and plasma does a close and restart over about 15 seconds or so. I can still use open programs on whichever virtual desktop I am currently using while plasma is restarting.

I also tried something like:

killall plasmashell; kstart plasmashell

Or even this:

killall plasmashell; kwin --replace && kstart plasmashell

But, for, unknown reasons, it didn't work.

Plasma desktop restarting began to work after I added sleeps among the commands:

killall plasmashell ; sleep 3 ; kwin --replace ; sleep 5 ; kstart plasmashell

Finally, I've noticed that, when type 'kwin|plasma' in KSysGuard filter field, it reports that after killing plasmashell, such *.so files are still present: desktop.so, file.so. We must kill them too. Otherwise, we'll have copies of that files after each restart.

So, the final plasma desktop restarting commands are:

killall plasmashell desktop.so file.so ; sleep 5 ; kwin --replace ; sleep 5 ; kstart plasmashell