sd_seat_get_active, sd_seat_get_sessions, sd_seat_can_multi_session, sd_seat_can_tty, sd_seat_can_graphical — Determine state of a specific seat
#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 ***sessions, | |
| uid_t **uid, | |
unsigned int *n_uids); |
int sd_seat_can_multi_session( | const char *seat); |
int sd_seat_can_tty( | const char *seat); |
int sd_seat_can_graphical( | const char *seat); |
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. The
two arrays and the latter parameter may be passed as
NULL in case these values need not to be
determined. 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_multi_session()
may be used to determine whether a specific seat is
capable of multi-session, i.e. allows multiple login
sessions in parallel (with only one being active at a
time).
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.
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_multi_session,
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.
The sd_seat_get_active(),
sd_seat_get_sessions(),
sd_seat_can_multi_session(),
sd_seat_can_tty() and
sd_seat_can_grapical() interfaces
are available as a shared library, which can be compiled
and linked to with the
libsystemd pkg-config(1)
file.