SD_UID_GET_STATE(3) sd_uid_get_state SD_UID_GET_STATE(3)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);
DESCRIPTIONsd_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.
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().
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 a shared library, which
can be compiled and linked to with the libsystemd pkg-config(1) file.
SEE ALSOsystemd(1), sd-login(3), sd_pid_get_owner_uid(3)systemd 212SD_UID_GET_STATE(3)
