With the advent of systemd --user sessions, it's become very interesting to spawn X as a user unit, as well as accompanying processes that may have previously been in a .xinitrc/.xsession, or even just to replace a collection of XDG/GDM/KDM/etc session files with independent systemd --user units. The simplest case here would be to login on a tty, with the traditional /usr/sbin/login "login manager".
However, systemd --user (spawned by user@.service) is at the top level of the slice for the user, and does not inherit any environment variables from the login process. Given the number of common applications which rely on SHELL being set in the environment, it seems like the cleanest way to provide this variable is to set it to %s in the user@.service.
Ideally in the long-term, applications which rely on SHELL being set should be fixed to just grab it from getpwnam() or similar, but until that becomes more common, I propose this simple change to make user sessions a little bit nicer out of the box.
systemd-logind will start user@.service. user@.service unit uses
PAM with service name 'systemd-user' to perform account and session
managment tasks. Previously, the name was 'systemd-shared', it is
now changed to 'systemd-user'.
Most PAM installations use one common setup for different callers.
Based on a quick poll, distributions fall into two camps: those that
have system-auth (Redhat, Fedora, CentOS, Arch, Gentoo, Mageia,
Mandriva), and those that have common-auth (Debian, Ubuntu, OpenSUSE).
Distributions that have system-auth have just one configuration file
that contains auth, password, account, and session blocks, and
distributions that have common-auth also have common-session,
common-password, and common-account. It is thus impossible to use one
configuration file which would work for everybody. systemd-user now
refers to system-auth, because it seems that the approach with one
file is more popular and also easier, so let's follow that.
In order to prepare things for the single-writer cgroup scheme, let's
make logind use systemd's own primitives for cgroup management.
Every login user now gets his own private slice unit, in which his sessions
live in a scope unit each. Also, add user@$UID.service to the same
slice, and implicitly start it on first login.
While most folks will be using the derivative from user-session-units,
I'm updating this one to reflect some of the fixes and things to note
about user sessions:
- cgroup should be set with "%u" - username instead of %I
- set dbus path with %U explicitly too
- hint to folks that wish to use MEM_CG features in user sessions
- allow unit to be enabled for instances with systemctl enable
We finally got the OK from all contributors with non-trivial commits to
relicense systemd from GPL2+ to LGPL2.1+.
Some udev bits continue to be GPL2+ for now, but we are looking into
relicensing them too, to allow free copy/paste of all code within
systemd.
The bits that used to be MIT continue to be MIT.
The big benefit of the relicensing is that closed source code may now
link against libsystemd-login.so and friends.
