SD-LOGIN(3)                       sd-login                       SD-LOGIN(3)

NAME         top

       sd-login - APIs for tracking logins

SYNOPSIS         top

       #include <systemd/sd-login.h>

       pkg-config --cflags --libs libsystemd

DESCRIPTION         top

       sd-login.h provides APIs to introspect and monitor seat, login
       session and user status information on the local system.

       See Multi-Seat on Linux[1] for an introduction into multi-seat
       support on Linux, the background for this set of APIs.

       Note that these APIs only allow purely passive access and monitoring
       of seats, sessions and users. To actively make changes to the seat
       configuration, terminate login sessions, or switch session on a seat
       you need to utilize the D-Bus API of systemd-logind, instead.

       These functions synchronously access data in /proc, /sys/fs/cgroup
       and /run. All of these are virtual file systems, hence the runtime
       cost of the accesses is relatively cheap.

       It is possible (and often a very good choice) to mix calls to the
       synchronous interface of sd-login.h with the asynchronous D-Bus
       interface of systemd-logind. However, if this is done you need to
       think a bit about possible races since the stream of events from
       D-Bus and from sd-login.h interfaces such as the login monitor are
       asynchronous and not ordered against each other.

       If the functions return string arrays, these are generally NULL
       terminated and need to be freed by the caller with the libc free(3)
       call after use, including the strings referenced therein. Similarly,
       individual strings returned need to be freed, as well.

       As a special exception, instead of an empty string array NULL may be
       returned, which should be treated equivalent to an empty string

       See sd_pid_get_session(3), sd_uid_get_state(3),
       sd_session_is_active(3), sd_seat_get_active(3), sd_get_seats(3),
       sd_login_monitor_new(3) for more information about the functions

NOTES         top

       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

SEE ALSO         top

       systemd(1), sd_pid_get_session(3), sd_uid_get_state(3),
       sd_session_is_active(3), sd_seat_get_active(3), sd_get_seats(3),
       sd_login_monitor_new(3), sd-daemon(3), pkg-config(1)

NOTES         top

        1. Multi-Seat on Linux

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug
       report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2019-05-09.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2019-05-09.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
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       of the original manual page), send a mail to

systemd 234                                                      SD-LOGIN(3)

Pages that refer to this page: sd_get_seats(3)sd_login_monitor_new(3)sd_machine_get_class(3)sd_pid_get_session(3)sd_seat_get_active(3)sd_session_is_active(3)sd_uid_get_state(3)systemd.directives(7)systemd.index(7)