Why is "xfwm4 --replace" running?

[vasa1]

I'm trying out Xubuntu 16.04 as guest OS in a virtual machine with Kubuntu 16.04 as host.

I notice that xfwm4 --replace seems to be running continuously. If it's not an artifact of running in a VM, why should xfwm4 --replace be running at all?

Edit: in top the same process appears simply as xfwm4 which seems logical :???:


vasa1@vasa1-xubu:~$ ps axjf | grep -i xfwm4
1119 1323 1302 1302 ? -1 S 1000 0:02 \_ xfwm4 --replace
1604 1869 1868 1604 pts/1 1868 S+ 1000 0:00 | \_ grep --color=auto -i xfwm4
vasa1@vasa1-xubu:~$

[ajgreeny]

I get the same output on my hard metal install of Xubuntu 16.04

user@XubuntuXenial:~$ ps axjf | grep -i xfwm4
138: 3447 3620 3596 3596 ? -1 S 1000 1:21 \_ xfwm4 --replace
153:18617 18637 18636 18617 pts/1 18636 S+ 1000 0:00 | \_ grep -n --color -i xfwm4
user@XubuntuXenial:~$
so I don't think it has anything to do with yours being a VM.

I will have a look shortly at my 18.04 virtual installation in VBox to see if the same is true of that.

EDIT:
Yes, it's the same in 18.04 as well.
Interesting find but I'm not sure what to make of it; I wonder if all the Ubuntu OS DE versions have the same or similar output for whichever WM is used by them.

I have VMs of Ubuntu 18.04 and Lubuntu 18.04 so will check them when I get spare time and report back.

[VMC]

Same with my 17.10 xubuntu:

1 844 720 720 ? -1 S 1000 0:00 xfwm4 --replace
1304 1317 1316 1304 pts/0 1316 S+ 1000 0:00 \_ grep --color=auto -i xfwm4
but with my manjaro xfce I don't get "--replace". Its only on ubuntu . Interesting.

xubuntu 17.10

$ xfwm4 --version
This is xfwm4 version 4.12.4 (revision 7844952) for Xfce 4.12
Released under the terms of the GNU General Public License.
Compiled against GTK+-2.24.31, using GTK+-2.24.31.


Build configuration and supported features:
- Startup notification support: Yes
- XSync support: Yes
- Render support: Yes
- Xrandr support: Yes
- Embedded compositor: Yes
- KDE systray proxy (deprecated): No

[vasa1]

...
Yes, it's the same in 18.04 as well.
Interesting find but I'm not sure what to make of it; I wonder if all the Ubuntu OS DE versions have the same or similar output for whichever WM is used by them.

I have VMs of Ubuntu 18.04 and Lubuntu 18.04 so will check them when I get spare time and report back.
I feel it should just be xfwm4.

If I understand correctly, the "--replace" is used to switch window managers during a session. So if I installed Openbox in Xubuntu and wished to make Openbox handle window management in a current session instead of xfwm4, I'd run openbox --replace.

https://unix.stackexchange.com/questions/298093/switch-window-manager-while-running
https://askubuntu.com/questions/159505/how-to-switch-windows-manager-on-the-fly

[VMC]

I think its just how it processed and executed the program. Notice the 'S' (sleep) besides 'xfwm4 --replace'

718 ? S 0:04 xfwm4 --replace 723 ? Sl 0:00 xfce4-panel
725 ? S 0:00 Thunar --daemon
727 ? Sl 0:01 xfdesktop
728 ? S 0:00 sh -c sleep 13;plank

Also notice the sleep I but on 'plank' from the Autostart. That has come and gone and now sleeping 'S'

[VMC]

Here's something strange. I booting non-graphical as stated here:
https://unix.stackexchange.com/questions/164005/non-graphical-boot-with-systemd/164028#164028

Then executed 'startx'. After boot-up I now have 'xf4wm4' without '--replace'


746 tty1 S+ 0:00 /bin/sh /usr/bin/startx
768 tty1 S+ 0:00 xinit /etc/X11/xinit/xinitrc -- /etc/X11/xinit/xserve
769 tty1 Sl 0:01 /usr/lib/xorg/Xorg -nolisten tcp :0 vt1 -keeptty -aut
774 tty1 S 0:00 /bin/sh /etc/xdg/xfce4/xinitrc -- /etc/X11/xinit/xser
784 ? Ss 0:00 /usr/bin/dbus-daemon --session --address=systemd: --n
812 ? Ss 0:00 /usr/bin/ssh-agent /usr/bin/im-launch x-session-manag
830 tty1 Sl 0:00 xfce4-session
834 ? S 0:00 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd
838 ? Ss 0:00 /usr/bin/gpg-agent --sh --daemon --write-env-file /ho
840 tty1 S 0:00 xfwm4
844 tty1 Sl 0:00 xfce4-panel
846 tty1 S 0:00 Thunar --daemon
848 tty1 Sl 0:00 xfdesktop
849 tty1 S 0:00 sh -c sleep 13;plank

[vasa1]

I've don't understand the intricacies of `ps` but

vasa1@vasa1-xubu:~$ ppp | grep -Ei "(PPID|xfwm4|firefox)" | cut -c -120
PPID PID PGID SID TTY TPGID STAT UID TIME COMMAND
1363 1567 1546 1546 ? -1 S 1000 0:08 \_ xfwm4 --replace
4107 4427 4426 4107 pts/2 4426 S+ 1000 0:00 | \_ grep --color=auto -Ei (PPID|xfwm4|firefox)
1363 4210 1579 1579 ? -1 Sl 1000 0:28 \_ /usr/lib/firefox/firefox
4210 4263 1579 1579 ? -1 Sl 1000 0:51 \_ /usr/lib/firefox/firefox -contentproc -childID
4210 4327 1579 1579 ? -1 Sl 1000 0:00 \_ /usr/lib/firefox/firefox -contentproc -childID
vasa1@vasa1-xubu:~$ while Firefox was playing a YouTube video.

And re. other desktop environments,
$ pgrep -a kwin
1775 kwin_x11
$