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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |NOTES |HISTORY |SEE ALSO |COLOPHON | |
SD_SEAT_GET_ACTIVE(3) sd_seat_get_activeSD_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 passedNULL, in case only one of the parameters shall be queried. The returned string needs to be freed with the libcfree(3) call after use.sd_seat_get_sessions()may be used to determine all sessions on the specified seat. Returns two arrays, one (NULLterminated) 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 asNULLin case these output values are not needed. The arrays and the strings referenced by them need to be freed with the libcfree(3) call after use. Note that instead of an empty arrayNULLmay 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 theseat parameter of any of these functions is passed asNULL, 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()andsd_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, orNULL, 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 thelibsystemd pkg-config(1) file. The code described here usesgetenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not callsetenv(3) from a parallel thread. It is recommended to only do calls tosetenv()from an early phase of the program when no other threads have been started.
sd_seat_can_tty()andsd_seat_can_graphical()were added in version 186.
systemd(1),sd-login(3),sd_session_get_seat(3)
This page is part of thesystemd (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 isnot part of the original manual page), send a mail to man-pages@man7.orgsystemd 258~rc2SD_SEAT_GET_ACTIVE(3)Pages that refer to this page:sd-login(3), systemd.directives(7), systemd.index(7)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |