sd_seat_can_tty(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 console.

       sd_seat_can_graphical() may be used to determine whether a specific
       seat provides graphics functionality, i.e. is useful as a graphics

       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

       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

HISTORY         top

       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         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 
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       report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-11-01.  (At that
       time, the date of the most recent commit that was found in the repos‐
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systemd 247                                            SD_SEAT_GET_ACTIVE(3)

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