trusty (3) sd_uid_get_state.3.gz

NAME

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

SYNOPSIS

       #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);

DESCRIPTION

       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 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.

       Similar, 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().

RETURN VALUE

       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. On failure, these calls return a negative errno-style error
       code.

NOTES

       The sd_uid_get_state(), sd_uid_is_on_seat(), sd_uid_get_sessions(), and sd_uid_get_seats() interfaces are
       available as shared library, which can be compiled and linked to with the libsystemd-loginpkg-config(1)
       file.

SEE ALSO

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