SD_LOGIN_MONITOR_NEW(3) sd_login_monitor_new SD_LOGIN_MONITOR_NEW(3)NAME
sd_login_monitor_new, sd_login_monitor_unref, sd_login_monitor_flush,
sd_login_monitor_get_fd - Monitor login sessions, seats and users
SYNOPSIS
#include <systemd/sd-login.h>
int sd_login_monitor_new(const char* category, sd_login_monitor** ret);
sd_login_monitor* sd_login_monitor_unref(sd_login_monitor* m);
int sd_login_monitor_flush(sd_login_monitor* m);
int sd_login_monitor_get_fd(sd_login_monitor* m);
DESCRIPTIONsd_login_monitor_new() may be used to monitor login session, users and
seats. Via a monitor object a file descriptor can be integrated into an
application defined event loop which is woken up each time a user logs
in, logs out or a seat is added or removed, or a session, user, or seat
changes state otherwise. The first parameter takes a string which can
be either seat (to get only notifications about seats being added,
removed or changed), session (to get only notifications about sessions
being created or removed or changed) or uid (to get only notifications
when a user changes state in respect to logins). If notifications shall
be generated in all these conditions, NULL may be passed. Note that in
future additional categories may be defined. The second parameter
returns a monitor object and needs to be freed with the
sd_login_monitor_unref() call after use.
sd_login_monitor_unref() may be used to destroy a monitor object. Note
that this will invalidate any file descriptor returned by
sd_login_monitor_get_fd().
sd_login_monitor_flush() may be used to reset the wakeup state of the
monitor object. Whenever an event causes the monitor to wake up the
event loop via the file descriptor this function needs to be called to
reset the wake-up state. If this call is not invoked the file
descriptor will immediately wake up the event loop again.
sd_login_monitor_get_fd() may be used to retrieve the file descriptor
of the monitor object that may be integrated in an application defined
event loop, based around poll(2) or a similar interface. The
application should include the returned file descriptor as wake up
source for POLLIN events. Whenever a wake-up is triggered the file
descriptor needs to be reset via sd_login_monitor_flush(). An
application needs to reread the login state with a function like
sd_get_seats(3) or similar to determine what changed.
RETURN VALUE
On success sd_login_monitor_new() and sd_login_monitor_flush() return 0
or a positive integer. On success sd_login_monitor_get_fd() returns a
Unix file descriptor. On failure, these calls return a negative
errno-style error code.
sd_login_monitor_unref() always returns NULL.
NOTES
The sd_login_monitor_new(), sd_login_monitor_unref(),
sd_login_monitor_flush() and sd_login_monitor_get_fd() interfaces are
available as shared library, which can be compiled and linked to with
the libsystemd-login pkg-config(1) file.
SEE ALSOsystemd(1), sd-login(7), sd_get_seats(3)AUTHOR
Lennart Poettering <lennart@poettering.net>
Developer
systemd 05/23/2012 SD_LOGIN_MONITOR_NEW(3)
