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NAME | SYNOPSIS | DESCRIPTION | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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sigevent(3type) sigevent(3type)
sigevent, sigval - structure for notification from asynchronous
routines
#include <signal.h>
struct sigevent {
int sigev_notify; /* Notification type */
int sigev_signo; /* Signal number */
union sigval sigev_value; /* Data passed with notification */
typeof(void (union sigval)) *sigev_notify_function;
/* Notification function
(SIGEV_THREAD) */
pthread_attr_t *sigev_notify_attributes;
/* Notification attributes */
/* Linux only: */
pid_t sigev_notify_thread_id;
/* ID of thread to signal
(SIGEV_THREAD_ID) */
};
union sigval { /* Data passed with notification */
int sival_int; /* Integer value */
void *sival_ptr; /* Pointer value */
};
sigevent
The sigevent structure is used by various APIs to describe the way
a process is to be notified about an event (e.g., completion of an
asynchronous request, expiration of a timer, or the arrival of a
message).
The definition shown in the SYNOPSIS is approximate: some of the
fields in the sigevent structure may be defined as part of a
union. Programs should employ only those fields relevant to the
value specified in sigev_notify.
The sigev_notify field specifies how notification is to be
performed. This field can have one of the following values:
SIGEV_NONE
A "null" notification: don't do anything when the event
occurs.
SIGEV_SIGNAL
Notify the process by sending the signal specified in
sigev_signo.
If the signal is caught with a signal handler that was
registered using the sigaction(2) SA_SIGINFO flag, then the
following fields are set in the siginfo_t structure that is
passed as the second argument of the handler:
si_code
This field is set to a value that depends on the API
delivering the notification.
si_signo
This field is set to the signal number (i.e., the
same value as in sigev_signo).
si_value
This field is set to the value specified in
sigev_value.
Depending on the API, other fields may also be set in the
siginfo_t structure.
The same information is also available if the signal is
accepted using sigwaitinfo(2).
SIGEV_THREAD
Notify the process by invoking sigev_notify_function "as
if" it were the start function of a new thread. (Among the
implementation possibilities here are that each timer
notification could result in the creation of a new thread,
or that a single thread is created to receive all
notifications.) The function is invoked with sigev_value
as its sole argument. If sigev_notify_attributes is not
NULL, it should point to a pthread_attr_t structure that
defines attributes for the new thread (see
pthread_attr_init(3)).
SIGEV_THREAD_ID (Linux-specific)
Currently used only by POSIX timers; see timer_create(2).
sigval
Data passed with a signal.
POSIX.1-2008.
POSIX.1-2001.
<aio.h> and <time.h> define sigevent since POSIX.1-2008.
The following headers also provide sigevent: <aio.h>, <mqueue.h>,
and <time.h>.
timer_create(2), getaddrinfo_a(3), lio_listio(3), mq_notify(3),
pthread_sigqueue(3), sigqueue(3), aiocb(3type), siginfo_t(3type)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 sigevent(3type)
Pages that refer to this page: timer_create(2), aio_cancel(3), aio_fsync(3), aio_read(3), aio_write(3), getaddrinfo_a(3), lio_listio(3), mq_notify(3), aio(7), pthreads(7), signal(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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