1SD_SEAT_GET_ACTIVE(3) sd_seat_get_active SD_SEAT_GET_ACTIVE(3)
2
6 sd_seat_get_active, sd_seat_get_sessions, sd_seat_can_tty,
7 sd_seat_can_graphical - Determine state of a specific seat
8
10 #include <systemd/sd-login.h>
11 int sd_seat_get_active(const char *seat, char **session, uid_t *uid);
13 int sd_seat_get_sessions(const char *seat, char ***ret_sessions,
15 uid_t **ret_uids, unsigned int *ret_n_uids);
16 int sd_seat_can_tty(const char *seat);
18 int sd_seat_can_graphical(const char *seat);
20
22 sd_seat_get_active() may be used to determine which session is
23 currently active on a seat, if there is any. Returns the session
24 identifier and the user identifier of the Unix user the session is
25 belonging to. Either the session or the user identifier parameter can
26 be passed NULL, in case only one of the parameters shall be queried.
27 The returned string needs to be freed with the libc free(3) call after
28 use.
29 sd_seat_get_sessions() may be used to determine all sessions on the
31 specified seat. Returns two arrays, one (NULL terminated) with the
32 session identifiers of the sessions and one with the user identifiers
33 of the Unix users the sessions belong to. An additional parameter may
34 be used to return the number of entries in the latter array. This value
35 is the same as the return value if the return value is nonnegative. The
36 output parameters may be passed as NULL in case these output values are
37 not needed. The arrays and the strings referenced by them need to be
38 freed with the libc free(3) call after use. Note that instead of an
39 empty array NULL may be returned and should be considered equivalent to
40 an empty array.
41 sd_seat_can_tty() may be used to determine whether a specific seat
43 provides TTY functionality, i.e. is useful as a text console.
44 sd_seat_can_graphical() may be used to determine whether a specific
46 seat provides graphics functionality, i.e. is useful as a graphics
47 display.
48 If the seat parameter of any of these functions is passed as NULL, the
50 operation is executed for the seat of the session of the calling
51 process, if there is any.
52
54 On success, sd_seat_get_active() returns 0 or a positive integer. On
55 success, sd_seat_get_sessions() returns the number of entries in the
56 session identifier array. If the test succeeds, sd_seat_can_tty() and
57 sd_seat_can_graphical() return a positive integer, if it fails 0. On
58 failure, these calls return a negative errno-style error code.
59 Errors
61 Returned errors may indicate the following problems:
62 -ENODATA
64 The given field is not specified for the described seat.
65 -ENXIO
67 The specified seat is unknown.
68 -EINVAL
70 An input parameter was invalid (out of range, or NULL, where that
71 is not accepted).
72 -ENOMEM
74 Memory allocation failed.
75
77 Functions described here are available as a shared library, which can
78 be compiled against and linked to with the libsystemd pkg-config(1)
79 file.
80 The code described here uses getenv(3), which is declared to be not
82 multi-thread-safe. This means that the code calling the functions
83 described here must not call setenv(3) from a parallel thread. It is
84 recommended to only do calls to setenv() from an early phase of the
85 program when no other threads have been started.
86
88 In the past, sd_seat_can_multi_session() was used to check whether the
89 seat supports multiple sessions. All seats support that now, so that
90 function has been deprecated and always returns true.
91
93 systemd(1), sd-login(3), sd_session_get_seat(3)
94systemd 254 SD_SEAT_GET_ACTIVE(3)