sd_uid_get_state(3) — Linux manual page


SD_UID_GET_STATE(3)         sd_uid_get_state         SD_UID_GET_STATE(3)

NAME         top

       sd_uid_get_state, sd_uid_is_on_seat, sd_uid_get_sessions,
       sd_uid_get_seats, sd_uid_get_display, sd_uid_get_login_time -
       Determine login state of a specific Unix user ID

SYNOPSIS         top

       #include <systemd/sd-login.h>

       int sd_uid_get_state(uid_t uid, char **state);

       int sd_uid_is_on_seat(uid_t uid, int require_active,
                             const char *seat);

       int sd_uid_get_sessions(uid_t uid, int require_active,
                               char ***sessions);

       int sd_uid_get_seats(uid_t uid, int require_active,
                            char ***seats);

       int sd_uid_get_display(uid_t uid, char **session);

       int sd_uid_get_login_time(uid_t uid, uint64_t *usec);

DESCRIPTION         top

       sd_uid_get_state() may be used to determine the login state of a
       specific Unix user identifier. The following states are currently
       known: "offline" (user not logged in at all), "lingering" (user
       not logged in, but some user services running), "online" (user
       logged in, but not active, i.e. has no session in the
       foreground), "active" (user logged in, and has at least one
       active session, i.e. one session in the foreground), "closing"
       (user not logged in, and not lingering, but some processes are
       still around). In the future additional states might be defined,
       client code should be written to be robust in regards to
       additional state strings being returned. The returned string
       needs to be freed with the libc free(3) call after use.

       sd_uid_is_on_seat() may be used to determine whether a specific
       user is logged in or active on a specific seat. Accepts a Unix
       user identifier and a seat identifier string as parameters. The
       require_active parameter is a boolean value. If non-zero (true),
       this function will test if the user is active (i.e. has a session
       that is in the foreground and accepting user input) on the
       specified seat, otherwise (false) only if the user is logged in
       (and possibly inactive) on the specified seat.

       sd_uid_get_sessions() may be used to determine the current
       sessions of the specified user. Accepts a Unix user identifier as
       parameter. The require_active parameter controls whether the
       returned list shall consist of only those sessions where the user
       is currently active (> 0), where the user is currently online but
       possibly inactive (= 0), or logged in but possibly closing the
       session (< 0). The call returns a NULL terminated string array of
       session identifiers in sessions which needs to be freed by the
       caller with the libc free(3) call after use, including all the
       strings referenced. If the string array parameter is passed as
       NULL, the array will not be filled in, but the return code still
       indicates the number of current sessions. Note that instead of an
       empty array NULL may be returned and should be considered
       equivalent to an empty array.

       Similarly, sd_uid_get_seats() may be used to determine the list
       of seats on which the user currently has sessions. Similar
       semantics apply, however note that the user may have multiple
       sessions on the same seat as well as sessions with no attached
       seat and hence the number of entries in the returned array may
       differ from the one returned by sd_uid_get_sessions().

       sd_uid_get_display() returns the name of the "primary" session of
       a user. If the user has graphical sessions, it will be the oldest
       graphical session. Otherwise, it will be the oldest open session.

       sd_uid_get_login_time() may be used to determine the time the
       user's service manager has been invoked, which is the time when
       the user's first active session, since which they stayed logged
       in continuously, began. The usec is in microseconds since the
       epoch (CLOCK_REALTIME). This call will fail with -ENXIO if the
       user is not currently logged in.

RETURN VALUE         top

       On success, sd_uid_get_state() and sd_uid_get_login_time()
       returns 0 or a positive integer. If the test succeeds,
       sd_uid_is_on_seat() returns a positive integer; if it fails, 0.
       sd_uid_get_sessions() and sd_uid_get_seats() return the number of
       entries in the returned arrays.  sd_uid_get_display() returns a
       non-negative code on success. 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 user.

           The specified seat is unknown.

           An input parameter was invalid (out of range, or NULL, where
           that is not accepted). This is also returned if the passed
           user ID is 0xFFFF or 0xFFFFFFFF, which are undefined on

           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_uid_get_display() was added in version 213.

       sd_uid_get_login_time() was added in version 254.

SEE ALSO         top

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

COLOPHON         top

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       This page was obtained from the project's upstream Git repository
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systemd 255                                          SD_UID_GET_STATE(3)

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