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NAME | SYNOPSIS | DESCRIPTION | CONTROLLING RESOURCES FOR LOGGED-IN USERS | EXAMPLES | SEE ALSO | COLOPHON |
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USER@.SERVICE(5) user@.service USER@.SERVICE(5)
user@.service, user-runtime-dir@.service, systemd-user-runtime-dir
- System units to start the user manager
user@UID.service
user-runtime-dir@UID.service
/usr/lib/systemd/systemd-user-runtime-dir
user-UID.slice
The systemd(1) system manager (PID 1) starts user manager
instances as user@UID.service, with the user's numerical UID used
as the instance identifier. These instances use the same
executable as the system manager, but running in a mode where it
starts a different set of units. Each systemd --user instance
manages a hierarchy of units specific to that user. See systemd(1)
for a discussion of units and systemd.special(7) for a list of
units that form the basis of the unit hierarchies of system and
user units.
user@UID.service is accompanied by the system unit
user-runtime-dir@UID.service, which creates the user's runtime
directory /run/user/UID when started, and removes it when it is
stopped. It also might apply runtime quota settings on /tmp/
and/or /dev/shm/ for the user. user-runtime-dir@UID.service
executes the systemd-user-runtime-dir binary to do the actual
work.
User processes may be started by the user@.service instance, in
which case they will be part of that unit in the system hierarchy.
They may also be started elsewhere, for example by sshd(8) or a
display manager like gdm, in which case they form a .scope unit
(see systemd.scope(5)). Both user@UID.service and the scope units
are collected under the user-UID.slice.
Individual user-UID.slice slices are collected under user.slice,
see systemd.special(7).
Options that control resources available to logged-in users can be
configured at a few different levels. As described in the previous
section, user.slice contains processes of all users, so any
resource limits on that slice apply to all users together. The
usual way to configure them would be through drop-ins, e.g.
/etc/systemd/system/user.slice.d/resources.conf.
The processes of a single user are collected under user-UID.slice.
Resource limits for that user can be configured through drop-ins
for that unit, e.g.
/etc/systemd/system/user-1000.slice.d/resources.conf. If the
limits should apply to all users instead, they may be configured
through drop-ins for the truncated unit name, user-.slice. For
example, configuration in
/etc/systemd/system/user-.slice.d/resources.conf is included in
all user-UID.slice units, see systemd.unit(5) for a discussion of
the drop-in mechanism.
When a user logs in and a .scope unit is created for the session
(see previous section), the creation of the scope may be managed
through pam_systemd(8). This PAM module communicates with
systemd-logind(8) to create the session scope and provide access
to hardware resources. Resource limits for the scope may be
configured through the PAM module configuration, see
pam_systemd(8). Configuring them through the normal unit
configuration is also possible, but since the name of the slice
unit is generally unpredictable, this is less useful.
In general any resources that apply to units may be set for
user@UID.service and the slice units discussed above, see
systemd.resource-control(5) for an overview.
Example 1. Hierarchy of control groups with two logged in users
$ systemd-cgls
Control group /:
-.slice
├─user.slice
│ ├─user-1000.slice
│ │ ├─user@1000.service
│ │ │ ├─pulseaudio.service
│ │ │ │ └─2386 /usr/bin/pulseaudio --daemonize=no
│ │ │ └─gnome-terminal-server.service
│ │ │ └─init.scope
│ │ │ ├─ 4127 /usr/libexec/gnome-terminal-server
│ │ │ └─ 4198 zsh
│ │ ...
│ │ └─session-4.scope
│ │ ├─ 1264 gdm-session-worker [pam/gdm-password]
│ │ ├─ 2339 /usr/bin/gnome-shell
│ │ ...
│ │ ├─session-19.scope
│ │ ├─6497 sshd: zbyszek [priv]
│ │ ├─6502 sshd: zbyszek@pts/6
│ │ ├─6509 -zsh
│ │ └─6602 systemd-cgls --no-pager
│ ...
│ └─user-1001.slice
│ ├─session-20.scope
│ │ ├─6675 sshd: guest [priv]
│ │ ├─6708 sshd: guest@pts/6
│ │ └─6717 -bash
│ └─user@1001.service
│ ├─init.scope
│ │ ├─6680 /usr/lib/systemd/systemd --user
│ │ └─6688 (sd-pam)
│ └─sleep.service
│ └─6706 /usr/bin/sleep 30
...
User with UID 1000 is logged in using gdm (session-4.scope) and
ssh(1) (session-19.scope), and also has a user manager instance
running (user@1000.service). User with UID 1001 is logged in using
ssh (session-20.scope) and also has a user manager instance
running (user@1001.service). Those are all (leaf) system units,
and form part of the slice hierarchy, with user-1000.slice and
user-1001.slice below user.slice. User units are visible below the
user@.service instances (pulseaudio.service,
gnome-terminal-server.service, init.scope, sleep.service).
Example 2. Default user resource limits
$ systemctl cat user-1000.slice
# /usr/lib/systemd/system/user-.slice.d/10-defaults.conf
# ...
[Unit]
Description=User Slice of UID %j
After=systemd-user-sessions.service
[Slice]
TasksMax=33%
The user-UID.slice units by default do not have a unit file. The
resource limits are set through a drop-in, which can be easily
replaced or extended following standard drop-in mechanisms
discussed in the first section.
systemd(1), systemd.service(5), systemd.slice(5),
systemd.resource-control(5), systemd.exec(5), systemd.special(7),
capsule@.service(5), pam(8)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-02-02. (At that
time, the date of the most recent commit that was found in the
repository was 2025-02-02.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~devel USER@.SERVICE(5)
Pages that refer to this page: systemd(1), capsule@.service(5), systemd.directives(7), systemd.index(7), systemd.special(7), pam_systemd(8)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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