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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_SEAT_GET_ACTIVE(3) sd_seat_get_active SD_SEAT_GET_ACTIVE(3)
sd_seat_get_active, sd_seat_get_sessions, 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 ***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);
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.
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.
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.
sd_seat_can_tty() and sd_seat_can_graphical() were added in
version 186.
systemd(1), sd-login(3), sd_session_get_seat(3)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SD_SEAT_GET_ACTIVE(3)
Pages that refer to this page: sd-login(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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