sigevent

<html> <head> <title>sigevent</title> <META NAME="KEYWORDS" CONTENT="sigevent"> </head> <body BGCOLOR="#ffffff" LINK="#0000ff" VLINK="#0000ff" ALINK="#0000ff" TEXT="#000000"> <center> <h1>sigevent</h1></center> <PRE> <A HREF="/man7/SIGEVENT">SIGEVENT(7)</A> Linux Programmer's Manual <A HREF="/man7/SIGEVENT">SIGEVENT(7)</A> NAME sigevent - structure for notification from asynchronous routines SYNOPSIS #include <signal.h> union sigval { /* Data passed with notification */ int sival_int; /* Integer value */ void *sival_ptr; /* Pointer value */ }; struct sigevent { int sigev_notify; /* Notification method */ int sigev_signo; /* Notification signal */ union sigval sigev_value; /* Data passed with notification */ void (*sigev_notify_function) (union sigval); /* Function used for thread notification (SIGEV_THREAD) */ void *sigev_notify_attributes; /* Attributes for notification thread (SIGEV_THREAD) */ pid_t sigev_notify_thread_id; /* ID of thread to signal (SIGEV_THREAD_ID) */ }; DESCRIPTION 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 asyn- chronous 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 regis- tered using the <A HREF="/man2/sigaction">sigaction(2)</A> SA_SIGINFO flag, then the follow- ing 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 sig- info_t structure. The same information is also available if the signal is ac- cepted using <A HREF="/man2/sigwaitinfo">sigwaitinfo(2)</A>. SIGEV_THREAD Notify the process by invoking sigev_notify_function "as if" it were the start function of a new thread. (Among the implemen- tation 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_no- tify_attributes is not NULL, it should point to a pthread_attr_t structure that defines attributes for the new thread (see <A HREF="/man3/pthread_attr_init">pthread_attr_init(3)</A>). SIGEV_THREAD_ID (Linux-specific) Currently used only by POSIX timers; see <A HREF="/man2/timer_create">timer_create(2)</A>. SEE ALSO <A HREF="/man2/timer_create">timer_create(2)</A>, <A HREF="/man3/aio_fsync">aio_fsync(3)</A>, <A HREF="/man3/aio_read">aio_read(3)</A>, <A HREF="/man3/aio_write">aio_write(3)</A>, getad- <A HREF="/man3/drinfo_a">drinfo_a(3)</A>, <A HREF="/man3/lio_listio">lio_listio(3)</A>, <A HREF="/man3/mq_notify">mq_notify(3)</A>, <A HREF="/man7/aio">aio(7)</A>, <A HREF="/man7/pthreads">pthreads(7)</A> COLOPHON This page is part of release 5.05 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. GNU 2017-07-13 <A HREF="/man7/SIGEVENT">SIGEVENT(7)</A></PRE> <center> <h6>Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2025 <a href="http://www.he.net">Hurricane Electric</a>. All Rights Reserved.</h6></center> </body> </html>

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