Yu Watanabe
0922f62126
- fix many links and drop unreachable links, - always use https rather than http if supported,
50 lines
3.9 KiB
Markdown
50 lines
3.9 KiB
Markdown
---
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title: Writing Desktop Environments
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category: Documentation for Developers
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layout: default
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SPDX-License-Identifier: LGPL-2.1-or-later
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---
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# Writing Desktop Environments
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_Or: how to hook up your favorite desktop environment with logind_
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systemd's logind service obsoletes ConsoleKit which was previously widely used on Linux distributions.
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This provides a number of new features, but also requires updating of the Desktop Environment running on it, in a few ways.
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This document should be read together with [Writing Display Managers](/WRITING_DISPLAY_MANAGERS) which focuses on the porting work necessary for display managers.
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If required it is possible to implement ConsoleKit and systemd-logind support in the same desktop environment code, detecting at runtime which interface is needed.
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The [sd_booted()](https://www.freedesktop.org/software/systemd/man/latest/sd_booted.html) call may be used to determine at runtime whether systemd is used.
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To a certain level ConsoleKit and systemd-logind may be used side-by-side, but a number of features are not available if ConsoleKit is used.
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Please have a look at the [Bus API of logind](https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.login1.html) and the C API as documented in [sd-login(7)](https://www.freedesktop.org/software/systemd/man/latest/sd-login.html). (Also see below)
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Here are the suggested changes:
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- Your session manager should listen to "Lock" and "Unlock" messages that are emitted from the session object logind exposes for your DE session, on the system bus.
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If "Lock" is received the screen lock should be activated, if "Unlock" is received it should be deactivated.
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This can easily be tested with "loginctl lock-sessions".
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See the [Bus API of logind](https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.login1.html) for further details.
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- Whenever the session gets idle the DE should invoke the SetIdleHint(True) call on the respective session object on the session bus.
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This is necessary for the system to implement auto-suspend when all sessions are idle.
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If the session gets used again it should call SetIdleHint(False).
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A session should be considered idle if it didn't receive user input (mouse movements, keyboard) in a while.
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See the [Bus API of logind](https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.login1.html) for further details.
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- To reboot/power-off/suspend/hibernate the machine from the DE use logind's bus calls Reboot(), PowerOff(), Suspend(), Hibernate(), HybridSleep().
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For further details see [Bus API of logind](https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.login1.html).
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- If your session manager handles the special power, suspend, hibernate hardware keys or the laptop lid switch on its own it is welcome to do so,
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but needs to disable logind's built-in handling of these events.
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Take one or more of the _handle-power-key_, _handle-suspend-key_, _handle-hibernate-key_, _handle-lid-switch_ inhibitor locks for that.
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See [Inhibitor Locks](/INHIBITOR_LOCKS) for further details on this.
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- Before rebooting/powering-off/suspending/hibernating and when the operation is triggered by the user by clicking on some UI elements
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(or suchlike) it is recommended to show the list of currently active inhibitors for the operation, and ask the user to acknowledge the operation.
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Note that PK often allows the user to execute the operation ignoring the inhibitors.
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Use logind's ListInhibitors() call to get a list of these inhibitors. See [Inhibitor Locks](/INHIBITOR_LOCKS) for further details on this.
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- If your DE contains a process viewer of some kind ("system monitor") it's a good idea to show session, service and seat information for each process.
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Use sd_pid_get_session(), sd_pid_get_unit(), sd_session_get_seat() to determine these.
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For details see [sd-login(7)](https://www.freedesktop.org/software/systemd/man/latest/sd-login.html).
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And that's all! Thank you!
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