sd_get_seats(3) — Linux manual page


SD_GET_SEATS(3)               sd_get_seats               SD_GET_SEATS(3)

NAME         top

       sd_get_seats, sd_get_sessions, sd_get_uids, sd_get_machine_names
       - Determine available seats, sessions, logged in users and
       virtual machines/containers

SYNOPSIS         top

       #include <systemd/sd-login.h>

       int sd_get_seats(char ***seats);

       int sd_get_sessions(char ***sessions);

       int sd_get_uids(uid_t **users);

       int sd_get_machine_names(char ***machines);

DESCRIPTION         top

       sd_get_seats() may be used to determine all currently available
       local seats. Returns the number of seat identifiers and if the
       input pointer is non-NULL, a NULL-terminated array of seat
       identifiers is stored at the address. The returned array and all
       strings it references 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.

       Similarly, sd_get_sessions() may be used to determine all current
       login sessions.

       Similarly, sd_get_uids() may be used to determine all Unix users
       who currently have login sessions.

       Similarly, sd_get_machine_names() may be used to determine all
       current virtual machines and containers on the system.

       Note that the returned lists are not sorted and in an undefined

RETURN VALUE         top

       On success, sd_get_seats(), sd_get_sessions(), sd_get_uids() and
       sd_get_machine_names() return the number of entries in the
       arrays. On failure, these calls return a negative errno-style
       error code.

       Returned errors may indicate the following problems:

           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_get_machine_names() was added in version 203.

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
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       (which is not part of the original manual page), send a mail to

systemd 255                                              SD_GET_SEATS(3)

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