Origin of /var/run contents

[Jonathan de Boyne Pollard]

Gene Heskett:

Didn't anyone think of the stuff that runs as a user?
They did.  They gave you a /run/user/$UID directory owned by you, and an 
XDG_RUNTIME_DIR environment variable whose value points to it that you 
use so that its location is configurable.  They also gave you a manual 
entry.

* 
https://freedesktop.org/software/systemd/man/file-hierarchy.html#Runtime%20Data

* 
https://manpages.debian.org/wheezy/systemd/file-hierarchy.7.en.html#RUNTIME_DATA

* https://unix.stackexchange.com/questions/162900/

* http://jdebp.eu./Softwares/nosh/guide/gazetteer.html#user-runtime

* http://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s15.html

* https://wiki.debian.org/ReleaseGoals/RunDirectory

* https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=635131

* 
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/migration_planning_guide/sect-red_hat_enterprise_linux-migration_planning_guide-file_system_layout#sect-Red_Hat_Enterprise_Linux-Migration_Planning_Guide-File_System_Layout-Changes_to_the_run_directory