Elogind User, Seat and Session Manager
Elogind is the systemd project's "logind", extracted out to be a
standalone daemon. It integrates with PAM to know the set of users
that are logged in to a system and whether they are logged in
graphically, on the console, or remotely. Elogind exposes this
information via the standard org.freedesktop.login1 D-Bus interface,
as well as through the file system using systemd's standard
/run/systemd layout. Elogind also provides "libelogind", which is a
subset of the facilities offered by "libsystemd". There is a
"libelogind.pc" pkg-config file as well.
All of the credit for elogind should go to the systemd developers.
For more on systemd, see
http://www.freedesktop.org/wiki/Software/systemd. All of the blame
should go to Andy Wingo, who extracted elogind from systemd.
Elogind was branched from systemd version 219, and preserves the git
history of the systemd project. The version of elogind is the
upstream systemd version, followed by the patchlevel of elogind. For
example version 219.12 is the twelfth elogind release, which aims to
provide a subset of the interfaces of systemd 219.
To contribute to elogind, fork the current source code from github:
Send a pull request for the changes you like.
To chat about elogind:
#guix on irc.freenode.org
Finally, bug reports:
Elogind has been developed for use in GuixSD, the OS distribution of
GNU Guix. See http://gnu.org/s/guix for more on Guix. GuixSD uses a
specific init manager (DMD), for reasons that are not relevant here,
but still aims to eventually be a full-featured distribution that can
run GNOME and other desktop environments. However, to run GNOME these
days means that you need to have support for the login1 D-Bus
interface, which is currently only provided by systemd. That is the
origin of this project: to take the excellent logind functionality
from systemd and provide it as a standalone package.
We like systemd. We realize that there are people out there that hate
it. You're welcome to use elogind for whatever purpose you like --
as-is, or as a jumping-off point for other things -- but please don't
use it as part of some anti-systemd vendetta. Systemd hackers are
smart folks that are trying to solve interesting problems on the free
desktop, and their large adoption is largely because they solve
problems that users and developers of user-focused applications care
about. We are appreciative of their logind effort and think that
everyone deserves to run it if they like, even if they use a different
Differences relative to systemd
The pkg-config file is called libelogind, not libsystemd or
The headers are in <elogind/...>, so like <elogind/sd-login.h> instead
Libelogind just implements login-related functionality. It also
provides the sd-bus API.
Unlike systemd, whose logind arranges to manage resources for user
sessions via RPC calls to systemd, in elogind there is no systemd so
there is no global cgroup-based resource management. This has a few
* Elogind does not create "slices" for users. Elogind will not
record that users are associated with slices.
* The /run/systemd/slices directory will always be empty.
* Elogind does not have the concept of a "scope", internally, as
it's the same as a session. Any API that refers to scopes will
always return an error code.
On the other hand, elogind does use a similar strategy to systemd in
that it places processes in a private cgroup for organizational
purposes, without installing any controllers (see
allows elogind to map arbitrary processes to sessions, even if the
process does the usual double-fork to be reparented to PID 1.
Elogind does not manage virtual terminals.
Elogind does monitor power button and the lid switch, like systemd,
but instead of doing RPC to systemd to suspend, poweroff, or restart
the machine, elogind just does this directly. For suspend, hibernate,
and hybrid-sleep, elogind uses the same code as systemd-sleep.
Instead of using a separate sleep.conf file to configure the sleep
behavior, this is included in the [Sleep] section of
/etc/elogind/login.conf. See the example login.conf for more. For
shutdown, reboot, and kexec, elogind shells out to "halt", "reboot",
and "kexec" binaries.
The loginctl command has the poweroff, reboot, sleep, hibernate, and
hybrid-sleep commands from systemd, as well as the --ignore-inhibitors
The PAM module is called pam_elogind.so, not pam_systemd.so.
Elogind and the running cgroup controller
While 'configure' runs, it will detect which controller is in place.
If no controller is in place, configure will determine, that elogind
should be its own controller, which will be a very limited one.
This approach should generally work, but if you just have no cgroup
controller in place, yet, or if you are currently switching to
another one, this approach will fail.
In this case you can do one of the two following things:
1) Boot your system with the target init system and cgroup
controller, before configuring and building elogind, or
2) Use the --with-cgroup-controller=name option.
Example: If you plan to use openrc, but openrc has not yet booted
the machine, you can use
to let elogind know that openrc will be the controller
However, if you set the controller at configure time to something
different than what is in place, elogind will not start until that
controller is actively used as the primary controller.
LGPLv2.1+ for all code
- except src/shared/MurmurHash2.c which is Public Domain
- except src/shared/siphash24.c which is CC0 Public Domain
- except src/journal/lookup3.c which is Public Domain
glibc >= 2.14
libmount >= 2.20 (from util-linux)
libseccomp >= 1.0.0 (optional)
libblkid >= 2.24 (from util-linux) (optional)
PAM >= 1.1.2 (optional)
make, gcc, and similar tools
During runtime, you need the following additional dependencies:
dbus >= 1.4.0 (strictly speaking optional, but recommended)
When building from git, you need the following additional