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 - Determine login state of a
8 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
25 sd_uid_get_state() may be used to determine the login state of a
26 specific Unix user identifier. The following states are currently
27 known: "offline" (user not logged in at all), "lingering" (user not
28 logged in, but some user services running), "online" (user logged in,
29 but not active, i.e. has no session in the foreground), "active" (user
30 logged in, and has at least one active session, i.e. one session in the
31 foreground), "closing" (user not logged in, and not lingering, but some
32 processes are still around). In the future additional states might be
33 defined, client code should be written to be robust in regards to
34 additional state strings being returned. The returned string needs to
35 be freed with the libc free(3) call after use.
36 sd_uid_is_on_seat() may be used to determine whether a specific user is
38 logged in or active on a specific seat. Accepts a Unix user identifier
39 and a seat identifier string as parameters. The require_active
40 parameter is a boolean value. If non-zero (true), this function will
41 test if the user is active (i.e. has a session that is in the
42 foreground and accepting user input) on the specified seat, otherwise
43 (false) only if the user is logged in (and possibly inactive) on the
44 specified seat.
45 sd_uid_get_sessions() may be used to determine the current sessions of
47 the specified user. Accepts a Unix user identifier as parameter. The
48 require_active parameter controls whether the returned list shall
49 consist of only those sessions where the user is currently active (>
50 0), where the user is currently online but possibly inactive (= 0), or
51 logged in at all but possibly closing the session (< 0). The call
52 returns a NULL terminated string array of session identifiers in
53 sessions which needs to be freed by the caller with the libc free(3)
54 call after use, including all the strings referenced. If the string
55 array parameter is passed as NULL, the array will not be filled in, but
56 the return code still indicates the number of current sessions. Note
57 that instead of an empty array NULL may be returned and should be
58 considered equivalent to an empty array.
59 Similarly, sd_uid_get_seats() may be used to determine the list of
61 seats on which the user currently has sessions. Similar semantics
62 apply, however note that the user may have multiple sessions on the
63 same seat as well as sessions with no attached seat and hence the
64 number of entries in the returned array may differ from the one
65 returned by sd_uid_get_sessions().
66 sd_uid_get_display() returns the name of the "primary" session of a
68 user. If the user has graphical sessions, it will be the oldest
69 graphical session. Otherwise, it will be the oldest open session.
70
72 On success, sd_uid_get_state() returns 0 or a positive integer. If the
73 test succeeds, sd_uid_is_on_seat() returns a positive integer; if it
74 fails, 0. sd_uid_get_sessions() and sd_uid_get_seats() return the
75 number of entries in the returned arrays. sd_uid_get_display() returns
76 a non-negative code on success. On failure, these calls return a
77 negative errno-style error code.
78 Errors
80 Returned errors may indicate the following problems:
81 -ENODATA
83 The given field is not specified for the described user.
84 -ENXIO
86 The specified seat is unknown.
87 -EINVAL
89 An input parameter was invalid (out of range, or NULL, where that
90 is not accepted). This is also returned if the passed user ID is
91 0xFFFF or 0xFFFFFFFF, which are undefined on Linux.
92 -ENOMEM
94 Memory allocation failed.
95
97 These APIs are implemented as a shared library, which can be compiled
98 and linked to with the libsystemd pkg-config(1) file.
99
101 systemd(1), sd-login(3), sd_pid_get_owner_uid(3)
102systemd 248 SD_UID_GET_STATE(3)