sd_uid_get_sessions(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 - 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);

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

       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 at all 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.

RETURN VALUE         top

       On success, sd_uid_get_state() 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 Linux.

           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.

SEE ALSO         top

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

COLOPHON         top

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       ⟨⟩.  This
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systemd 246                                              SD_UID_GET_STATE(3)

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