SD-LOGIN(3)sd-loginSD-LOGIN(3)NAMEsd-login - APIs for tracking logins
SYNOPSIS
#include <systemd/sd-login.h>
pkg-config --cflags --libs libsystemd-login
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-login pkg-config(1) file.
SEE ALSOsystemd(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), sd-readahead(3), pkg-config(1)NOTES
1. Multi-Seat on Linux
http://www.freedesktop.org/wiki/Software/systemd/multiseat
systemd 208SD-LOGIN(3)