1SD_UID_GET_STATE(3)            sd_uid_get_state            SD_UID_GET_STATE(3)
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NAME

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
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SYNOPSIS

11       #include <systemd/sd-login.h>
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13       int sd_uid_get_state(uid_t uid, char **state);
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15       int sd_uid_is_on_seat(uid_t uid, int require_active, const char *seat);
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17       int sd_uid_get_sessions(uid_t uid, int require_active,
18                               char ***sessions);
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20       int sd_uid_get_seats(uid_t uid, int require_active, char ***seats);
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22       int sd_uid_get_display(uid_t uid, char **session);
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DESCRIPTION

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.
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37       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.
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46       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.
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60       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().
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67       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.
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RETURN VALUE

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.
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ERRORS

80       Returned errors may indicate the following problems:
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82       -ENODATA
83           The given field is not specified for the described user.
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85       -ENXIO
86           The specified seat is unknown.
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88       -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
93       -ENOMEM
94           Memory allocation failed.
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NOTES

97       These APIs are implemented as a shared library, which can be compiled
98       and linked to with the libsystemd pkg-config(1) file.
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SEE ALSO

101       systemd(1), sd-login(3), sd_pid_get_owner_uid(3)
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105systemd 239                                                SD_UID_GET_STATE(3)
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