Apply changes or restart Unity dash/launcher/... without reboot or logout

Question

I was in the situation that an application I had was not available in the Unity applications lens after I removed a custom .desktop launcher file in my home directory that had overridden the system-wide one.

My problem was that I needed to apply those changes and update in this case the database of installed .desktop files, but other similar scenarios are also imaginable.

So what could I have done (and do the next time) instead of rebooting or logging out and back in to update the Unity configuration and force it to reload and reinitialize all of its stuff?

I am on 15.10, so unity --reset & does not work because it's deprecated.

I then tried unity --replace & instead, but that crashed my desktop and rendered my TTY7 unusable. It first flashed dark and looked like it was restarting Unity and restoring the desktop, but then it did not react to anything any more. Switching to TTY1 and back left me with a black screen plus mouse cursor. After rebooting via TTY1 login and reboot, it worked again and Unity even recognized my application now.

But if I would have been in a situation where a reboot or logout was no option, what would have been my way to go?

Solution 1

Press Alt+F2 type unity and press Enter.

Solution 2

• Unity is just a Compiz plugin, you can reload it using:

  compiz --replace
  

  Or to let you close terminal

  compiz --replace & disown
  

  To confirm, you can check:

  $ file `which unity`
  /usr/bin/unity: Python script, ASCII text executable
  
  $ more /usr/bin/unity
  

• Another way, light reload only the plugin (very quick)

  1. Create the compiz_plugin_reloader script

     Source: iXce’s blog: Compiz plugin reloader

     #!/usr/bin/env python
     
     '''Compiz plugin reloader (through compizconfig)
     Copyright (c) 2007 Guillaume Seguin <[email protected]>
     Licensed under GNU GPLv2'''
     
     import compizconfig
     from sys import argv, exit
     from time import sleep
     
     if __name__ == "__main__":
         if len (argv) < 2:
             print "Usage : %s plugin1 [plugin2 ... pluginN]" % argv[0]
             exit (2)
         plugins = argv[1:]
         context = compizconfig.Context (basic_metadata = True)
         print "Unloading " + " ".join (plugins)
         for plugin in plugins:
             if plugin not in context.Plugins:
                 print "Warning : %s plugin not found" % plugin
                 plugins.remove (plugin)
                 continue
             context.Plugins[plugin].Enabled = False
         if len (plugins) == 0:
             print "Error : no plugin found"
             exit (1)
         context.Write ()
         print "Waiting for settings update"
         sleep (2)
         print "Loading " + " ".join (plugins)
         for plugin in plugins:
             context.Plugins[plugin].Enabled = True
         context.Write ()
     

  2. Fix permissions

     chmod +x compiz_plugin_reloader
     

  3. Run as:

     ./compiz_plugin_reloader unityshell
     

Comments

[doug]

you can try setsid unity, it will 'refresh' unity. On one of my installs it does so, the other it results in a log out. Others seem to say it resets back to defaults, does not here in either case.

[Byte Commander]

Simple but genial. I have no idea why nobody thought of this earlier. I don't know how much of Unity gets restarted, but it's definitely enough to recognize overridden .desktop files. Thank you! I'll award you the bounty in a few days, waiting for further responses.

[Byte Commander]

Congratulations to your first bounty @padlyuck! :D

[George D]

Can you please elaborate on this ? What exactly does it do?

[padlyuck]

I found this solution here askubuntu.com/questions/495997/how-to-properly-restart-unity . I can not say for sure what makes this command. It decided my problem with no side effects, so I suggested it as a solution to this issue.

[davidA]

Beware - I did this on 14.04 and it shut down X (and all apps) and I had to log in again.