sd-login(3)

NAME

   sd-login - APIs for tracking logins

SYNOPSIS

   #include <systemd/sd-login.h>

   pkg-config --cflags --libs libsystemd

DESCRIPTION

   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 array.

   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
   implemented.

NOTES

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

SEE ALSO

   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

    1. Multi-Seat on Linux
       http://www.freedesktop.org/wiki/Software/systemd/multiseat

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