1SD_UID_GET_STATE(3) sd_uid_get_state SD_UID_GET_STATE(3)
2
6 sd_uid_get_state, sd_uid_is_on_seat, sd_uid_get_sessions,
7 sd_uid_get_seats, sd_uid_get_display, sd_uid_get_login_time - Determine
8 login state of a specific Unix user ID
9
11 #include <systemd/sd-login.h>
12 int sd_uid_get_state(uid_t uid, char **state);
14 int sd_uid_is_on_seat(uid_t uid, int require_active, const char *seat);
16 int sd_uid_get_sessions(uid_t uid, int require_active,
18 char ***sessions);
19 int sd_uid_get_seats(uid_t uid, int require_active, char ***seats);
21 int sd_uid_get_display(uid_t uid, char **session);
23 int sd_uid_get_login_time(uid_t uid, uint64_t *usec);
25
27 sd_uid_get_state() may be used to determine the login state of a
28 specific Unix user identifier. The following states are currently
29 known: "offline" (user not logged in at all), "lingering" (user not
30 logged in, but some user services running), "online" (user logged in,
31 but not active, i.e. has no session in the foreground), "active" (user
32 logged in, and has at least one active session, i.e. one session in the
33 foreground), "closing" (user not logged in, and not lingering, but some
34 processes are still around). In the future additional states might be
35 defined, client code should be written to be robust in regards to
36 additional state strings being returned. The returned string needs to
37 be freed with the libc free(3) call after use.
38 sd_uid_is_on_seat() may be used to determine whether a specific user is
40 logged in or active on a specific seat. Accepts a Unix user identifier
41 and a seat identifier string as parameters. The require_active
42 parameter is a boolean value. If non-zero (true), this function will
43 test if the user is active (i.e. has a session that is in the
44 foreground and accepting user input) on the specified seat, otherwise
45 (false) only if the user is logged in (and possibly inactive) on the
46 specified seat.
47 sd_uid_get_sessions() may be used to determine the current sessions of
49 the specified user. Accepts a Unix user identifier as parameter. The
50 require_active parameter controls whether the returned list shall
51 consist of only those sessions where the user is currently active (>
52 0), where the user is currently online but possibly inactive (= 0), or
53 logged in but possibly closing the session (< 0). The call returns a
54 NULL terminated string array of session identifiers in sessions which
55 needs to be freed by the caller with the libc free(3) call after use,
56 including all the strings referenced. If the string array parameter is
57 passed as NULL, the array will not be filled in, but the return code
58 still indicates the number of current sessions. Note that instead of an
59 empty array NULL may be returned and should be considered equivalent to
60 an empty array.
61 Similarly, sd_uid_get_seats() may be used to determine the list of
63 seats on which the user currently has sessions. Similar semantics
64 apply, however note that the user may have multiple sessions on the
65 same seat as well as sessions with no attached seat and hence the
66 number of entries in the returned array may differ from the one
67 returned by sd_uid_get_sessions().
68 sd_uid_get_display() returns the name of the "primary" session of a
70 user. If the user has graphical sessions, it will be the oldest
71 graphical session. Otherwise, it will be the oldest open session.
72 sd_uid_get_login_time() may be used to determine the time the user's
74 service manager has been invoked, which is the time when the user's
75 first active session, since which they stayed logged in continuously,
76 began. The usec is in microseconds since the epoch (CLOCK_REALTIME).
77 This call will fail with -ENXIO if the user is not currently logged in.
78
80 On success, sd_uid_get_state() and sd_uid_get_login_time() returns 0 or
81 a positive integer. If the test succeeds, sd_uid_is_on_seat() returns a
82 positive integer; if it fails, 0. sd_uid_get_sessions() and
83 sd_uid_get_seats() return the number of entries in the returned arrays.
84 sd_uid_get_display() returns a non-negative code on success. On
85 failure, these calls return a negative errno-style error code.
86 Errors
88 Returned errors may indicate the following problems:
89 -ENODATA
91 The given field is not specified for the described user.
92 -ENXIO
94 The specified seat is unknown.
95 -EINVAL
97 An input parameter was invalid (out of range, or NULL, where that
98 is not accepted). This is also returned if the passed user ID is
99 0xFFFF or 0xFFFFFFFF, which are undefined on Linux.
100 -ENOMEM
102 Memory allocation failed.
103
105 Functions described here are available as a shared library, which can
106 be compiled against and linked to with the libsystemd pkg-config(1)
107 file.
108 The code described here uses getenv(3), which is declared to be not
110 multi-thread-safe. This means that the code calling the functions
111 described here must not call setenv(3) from a parallel thread. It is
112 recommended to only do calls to setenv() from an early phase of the
113 program when no other threads have been started.
114
116 systemd(1), sd-login(3), sd_pid_get_owner_uid(3)
117systemd 254 SD_UID_GET_STATE(3)