x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_SEAT_GET_ACTIVE(3) sd_seat_get_active SD_SEAT_GET_ACTIVE(3)
NAME
sd_seat_get_active, sd_seat_get_sessions, sd_seat_can_tty,
sd_seat_can_graphical - Determine state of a specific seat
SYNOPSIS
#include <systemd/sd-login.h>
int sd_seat_get_active(const char *seat, char **session, uid_t *uid);
int sd_seat_get_sessions(const char *seat, char ***ret_sessions,
uid_t **ret_uids, unsigned int *ret_n_uids);
int sd_seat_can_tty(const char *seat);
int sd_seat_can_graphical(const char *seat);
DESCRIPTION
sd_seat_get_active() may be used to determine which session is
currently active on a seat, if there is any. Returns the session
identifier and the user identifier of the Unix user the session is
belonging to. Either the session or the user identifier parameter can
be passed NULL, in case only one of the parameters shall be queried.
The returned string needs to be freed with the libc free(3) call after
use.
sd_seat_get_sessions() may be used to determine all sessions on the
specified seat. Returns two arrays, one (NULL terminated) with the
session identifiers of the sessions and one with the user identifiers
of the Unix users the sessions belong to. An additional parameter may
be used to return the number of entries in the latter array. This value
is the same as the return value if the return value is nonnegative. The
output parameters may be passed as NULL in case these output values are
not needed. The arrays and the strings referenced by them need to be
freed with the libc free(3) call after use. Note that instead of an
empty array NULL may be returned and should be considered equivalent to
an empty array.
sd_seat_can_tty() may be used to determine whether a specific seat
provides TTY functionality, i.e. is useful as a text console.
sd_seat_can_graphical() may be used to determine whether a specific
seat provides graphics functionality, i.e. is useful as a graphics
display.
If the seat parameter of any of these functions is passed as NULL, the
operation is executed for the seat of the session of the calling
process, if there is any.
RETURN VALUE
On success, sd_seat_get_active() returns 0 or a positive integer. On
success, sd_seat_get_sessions() returns the number of entries in the
session identifier array. If the test succeeds, sd_seat_can_tty() and
sd_seat_can_graphical() return a positive integer, if it fails 0. On
failure, these calls return a negative errno-style error code.
Errors
Returned errors may indicate the following problems:
-ENODATA
The given field is not specified for the described seat.
-ENXIO
The specified seat is unknown.
-EINVAL
An input parameter was invalid (out of range, or NULL, where that
is not accepted).
-ENOMEM
Memory allocation failed.
NOTES
Functions described here are available as a shared library, which can
be compiled against and linked to with the libsystemd pkg-config(1)
file.
The code described here uses getenv(3), which is declared to be not
multi-thread-safe. This means that the code calling the functions
described here must not call setenv(3) from a parallel thread. It is
recommended to only do calls to setenv() from an early phase of the
program when no other threads have been started.
HISTORY
In the past, sd_seat_can_multi_session() was used to check whether the
seat supports multiple sessions. All seats support that now, so that
function has been deprecated and always returns true.
SEE ALSO
systemd(1), sd-login(3), sd_session_get_seat(3)
systemd 254 SD_SEAT_GET_ACTIVE(3)
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