sd_seat_get_active(3) — Linux manual page


SD_SEAT_GET_ACTIVE(3)      sd_seat_get_active      SD_SEAT_GET_ACTIVE(3)

NAME         top

       sd_seat_get_active, sd_seat_get_sessions, sd_seat_can_tty,
       sd_seat_can_graphical - Determine state of a specific seat

SYNOPSIS         top

       #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         top

       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

       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         top

       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.

       Returned errors may indicate the following problems:

           The given field is not specified for the described seat.

           The specified seat is unknown.

           An input parameter was invalid (out of range, or NULL, where
           that is not accepted).

           Memory allocation failed.

NOTES         top

       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

HISTORY         top

       sd_seat_can_tty() and sd_seat_can_graphical() were added in
       version 186.

SEE ALSO         top

       systemd(1), sd-login(3), sd_session_get_seat(3)

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨⟩.  If you have
       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-22.)  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

systemd 255                                        SD_SEAT_GET_ACTIVE(3)

Pages that refer to this page: sd-login(3)systemd.directives(7)systemd.index(7)