[root@testPCr97 ~]# journalctl -f -g gdm


### User switch from user test into gdm  (gdm)

Jun 16 09:34:43 testPCr97 systemd-logind[1072]: New session c3 of user gdm.
Jun 16 09:34:43 testPCr97 systemd[5428]: pam_unix(systemd-user:session): session opened for user gdm(uid=42) by gdm(uid=0)
Jun 16 09:34:43 testPCr97 systemd[1]: Started Session c3 of User gdm.
Jun 16 09:34:43 testPCr97 gdm-launch-environment][5423]: pam_unix(gdm-launch-environment:session): session opened for user gdm(uid=42) by (uid=0)
Jun 16 09:34:44 testPCr97 gnome-shell[5467]: Registering session with GDM


### loging in as user

Jun 16 09:34:51 testPCr97 gdm-password][5849]: pam_unix(gdm-password:session): session opened for user user(uid=1000) by user(uid=0)
Jun 16 09:34:53 testPCr97 gsd-color[1601]: failed to connect to device: Failed to connect to missing device /org/freedesktop/ColorManager/devices/xrandr_NEC_Corporation_E231W_23300189NB_gdm_42
Jun 16 09:34:53 testPCr97 gsd-color[6140]: failed to connect to device: Failed to connect to missing device /org/freedesktop/ColorManager/devices/xrandr_NEC_Corporation_E231W_23300189NB_gdm_42
Jun 16 09:34:54 testPCr97 gnome-shell[5949]: Registering session with GDM
Jun 16 09:34:58 testPCr97 gdm[1303]: Gdm: GdmCommon: process (pid:5423, command 'gdm-session-worker [pam/gdm-launch-environment]') isn't dying after 5 seconds, now ignoring it.
Jun 16 09:34:58 testPCr97 gdm-launch-environment][5423]: pam_unix(gdm-launch-environment:session): session closed for user gdm


#logging out from user  (no gdm 

Jun 16 09:35:10 testPCr97 gdm-password][5849]: pam_unix(gdm-password:session): session closed for user user


## swtiched back to test and logged out from  (gdm)

Jun 16 09:35:41 testPCr97 gdm-autologin][1315]: pam_unix(gdm-autologin:session): session closed for user test
Jun 16 09:35:41 testPCr97 systemd-logind[1072]: New session c4 of user gdm.
Jun 16 09:35:41 testPCr97 systemd[6728]: pam_unix(systemd-user:session): session opened for user gdm(uid=42) by gdm(uid=0)
Jun 16 09:35:41 testPCr97 systemd[1]: Started Session c4 of User gdm.
Jun 16 09:35:41 testPCr97 gdm-launch-environment][6722]: pam_unix(gdm-launch-environment:session): session opened for user gdm(uid=42) by (uid=0)
Jun 16 09:35:43 testPCr97 gnome-shell[6759]: Registering session with GDM



[root@testPCr97 ~]# rpm -qa | grep gdm 
gdm-40.1-31.el9.x86_64