1SIGEVENT(7)                Linux Programmer's Manual               SIGEVENT(7)
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NAME

6       sigevent - structure for notification from asynchronous routines
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SYNOPSIS

9       #include <signal.h>
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11       union sigval {          /* Data passed with notification */
12           int     sival_int;         /* Integer value */
13           void   *sival_ptr;         /* Pointer value */
14       };
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16       struct sigevent {
17           int          sigev_notify; /* Notification method */
18           int          sigev_signo;  /* Notification signal */
19           union sigval sigev_value;  /* Data passed with
20                                         notification */
21           void       (*sigev_notify_function) (union sigval);
22                            /* Function used for thread
23                               notification (SIGEV_THREAD) */
24           void        *sigev_notify_attributes;
25                            /* Attributes for notification thread
26                               (SIGEV_THREAD) */
27           pid_t        sigev_notify_thread_id;
28                            /* ID of thread to signal (SIGEV_THREAD_ID) */
29       };
30

DESCRIPTION

32       The  sigevent  structure  is used by various APIs to describe the way a
33       process is to be notified about an event (e.g., completion of an  asyn‐
34       chronous request, expiration of a timer, or the arrival of a message).
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36       The definition shown in the SYNOPSIS is approximate: some of the fields
37       in the sigevent structure may be defined as part of a union.   Programs
38       should  employ  only  those  fields  relevant to the value specified in
39       sigev_notify.
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41       The sigev_notify field specifies how notification is to  be  performed.
42       This field can have one of the following values:
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44       SIGEV_NONE
45               A "null" notification: don't do anything when the event occurs.
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47       SIGEV_SIGNAL
48               Notify   the   process  by  sending  the  signal  specified  in
49               sigev_signo.
50
51               If the signal is caught with a signal handler that  was  regis‐
52               tered  using the sigaction(2) SA_SIGINFO flag, then the follow‐
53               ing fields are set in the siginfo_t structure that is passed as
54               the second argument of the handler:
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56               si_code   This  field is set to a value that depends on the API
57                         delivering the notification.
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59               si_signo  This field is set to the  signal  number  (i.e.,  the
60                         same value as in sigev_signo).
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62               si_value  This   field   is  set  to  the  value  specified  in
63                         sigev_value.
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65               Depending on the API, other fields may also be set in the  sig‐
66               info_t structure.
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68               The  same  information  is  also  available  if  the  signal is
69               accepted using sigwaitinfo(2).
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71       SIGEV_THREAD
72               Notify the process by invoking sigev_notify_function "as if" it
73               were  the start function of a new thread.  (Among the implemen‐
74               tation possibilities here  are  that  each  timer  notification
75               could  result in the creation of a new thread, or that a single
76               thread is created to receive all notifications.)  The  function
77               is   invoked   with  sigev_value  as  its  sole  argument.   If
78               sigev_notify_attributes is not  NULL,  it  should  point  to  a
79               pthread_attr_t  structure  that  defines attributes for the new
80               thread (see pthread_attr_init(3)).
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82       SIGEV_THREAD_ID (Linux-specific)
83               Currently used only by POSIX timers; see timer_create(2).
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SEE ALSO

86       timer_create(2),  aio_fsync(3),   aio_read(3),   aio_write(3),   getad‐
87       drinfo_a(3), lio_listio(3), mq_notify(3), aio(7), pthreads(7)
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COLOPHON

90       This  page  is  part of release 4.16 of the Linux man-pages project.  A
91       description of the project, information about reporting bugs,  and  the
92       latest     version     of     this    page,    can    be    found    at
93       https://www.kernel.org/doc/man-pages/.
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97GNU                               2017-07-13                       SIGEVENT(7)
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