-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sun, Jan 15, 2017 at 09:47:40PM -0500, kamaraju kusumanchi wrote: > How can I find out the display manager currently running on a machine > from the command line?
Hm. How do you know there aren't two running? Or fifteen? Yes, I know the question sounds at first a bit grumpy/wisecracky. Bear with me :-) - From some perspective (e.g. you are a shell script running in some X terminal) still the notion of "the" display manager might make sense: that would be the one which is y display manager *and* your ancestor. Have a look at this tree snippet from my machine, obtained by "ps wauxf" (I snipped most of the columns and shortened things a bit): | /usr/bin/xdm | \_ /usr/lib/xorg/Xorg :0 vt7 -nolisten tcp -auth /var/lib[...] | \_ -:0 | \_ x-window-manager -s | \_ /usr/bin/ssh-agent x-window-manager | \_ xterm -fg rgb:ffff/ffff/ffff -bg rgb:0000/0000/5050 | | \_ bash | | \_ emacs | | \_ mutt | \_ /usr/lib/fvwm/2.6.5/FvwmCommandS 8 5 /home/tomas/.fvwm/config 0 8 | \_ /usr/lib/fvwm/2.6.5/FvwmButtons 9 4 none 0 8 | \_ /usr/lib/fvwm/2.6.5/FvwmIconMan 11 4 none 0 8 | \_ /usr/lib/fvwm/2.6.5/FvwmAnimate 13 4 none 0 8 | \_ /usr/lib/fvwm/2.6.5/FvwmPager 17 4 none 0 8 FvwmPager-Single * * | \_ xbiff -geometry +5000+5000 -bg rgb:7070/8c8c/8c8c -fg rgb:0000/0000/0000 | \_ xclock -norender -geometry +5000+5000 -bg rgb:7070/8c8c/8c8c -fg rgb[...] | \_ xterm -class bat -bg black -fg white -geometry +5000+5000 -fn xft:DejaVu [...] | | \_ watch -tn 10 bat | \_ xload -geometry +5000+5000 -bg rgb:7070/8c8c/8c8c -fg rgb:0000/0000/0000[...] | \_ xterm -fg rgb:ffff/ffff/ffff -bg rgb:0000/0000/5050 | | \_ bash | | \_ xscreensaver | | \_ fetchmail -Nkd 30 | \_ xterm -fg rgb:ffff/ffff/ffff -bg rgb:0000/0000/5050 | | \_ bash | | \_ /bin/bash /home/tomas/bin/tun | | \_ socat [...] | | \_ socat [...] | \_ xterm -fg rgb:ffff/ffff/ffff -bg rgb:0000/0000/5050 | | \_ bash | \_ xterm -fg rgb:ffff/ffff/ffff -bg rgb:0000/0000/5050 | | \_ bash | | \_ ssh to...@tuxteam.tun | \_ xterm -fg rgb:ffff/ffff/ffff -bg rgb:0000/0000/5050 | \_ bash | \_ ps wauxf | \_ bash The display manager(s) are thus the root(s) of those process trees which contain an X session (unless there's no login at the moment). If you are interested in "your" display manager, you only have to ascend your process tree until you hit a program which "is" a display manager. If you have control on your whole environment, you can make your life easier and set up your session to export a shell variable (the session above is this process with the funny name "-:0", which parents everything running under X in my box). There are admin-settable things in the session machinery (mainly in /etc/X11/xinit/, as shell script snippets which are dot-included (remember? they want to be able to set env vars) at start, and branch out, as needed, to per-user script snippets. This is a pretty "classical" view. No idea how things work under systemd or Wayland. Regards - -- tomás -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlh8lW8ACgkQBcgs9XrR2kZ6bgCfSWliySpBB0zhlwj0eQnM7a7O VnAAn1uUUjFebyJpnX/IpOm9HqSgGO+k =R7MN -----END PGP SIGNATURE-----