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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | STANDARDS | HISTORY | BUGS | SEE ALSO | COLOPHON |
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io_getevents(2) System Calls Manual io_getevents(2)
io_getevents - read asynchronous I/O events from the completion
queue
Standard C library (libc, -lc)
Alternatively, Asynchronous I/O library (libaio, -laio); see
VERSIONS.
#include <linux/aio_abi.h> /* Definition of *io_* types */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
int syscall(SYS_io_getevents, aio_context_t ctx_id,
long min_nr, long nr, struct io_event *events,
struct timespec *timeout);
Note: glibc provides no wrapper for io_getevents(), necessitating
the use of syscall(2).
Note: this page describes the raw Linux system call interface.
The wrapper function provided by libaio uses a different type for
the ctx_id argument. See VERSIONS.
The io_getevents() system call attempts to read at least min_nr
events and up to nr events from the completion queue of the AIO
context specified by ctx_id.
The timeout argument specifies the amount of time to wait for
events, and is specified as a relative timeout in a timespec(3)
structure.
The specified time will be rounded up to the system clock
granularity and is guaranteed not to expire early.
Specifying timeout as NULL means block indefinitely until at least
min_nr events have been obtained.
On success, io_getevents() returns the number of events read.
This may be 0, or a value less than min_nr, if the timeout
expired. It may also be a nonzero value less than min_nr, if the
call was interrupted by a signal handler.
For the failure return, see VERSIONS.
EFAULT Either events or timeout is an invalid pointer.
EINTR Interrupted by a signal handler; see signal(7).
EINVAL ctx_id is invalid. min_nr is out of range or nr is out of
range.
ENOSYS io_getevents() is not implemented on this architecture.
You probably want to use the io_getevents() wrapper function
provided by libaio.
Note that the libaio wrapper function uses a different type
(io_context_t) for the ctx_id argument. Note also that the libaio
wrapper does not follow the usual C library conventions for
indicating errors: on error it returns a negated error number (the
negative of one of the values listed in ERRORS). If the system
call is invoked via syscall(2), then the return value follows the
usual conventions for indicating an error: -1, with errno set to a
(positive) value that indicates the error.
Linux.
Linux 2.5.
An invalid ctx_id may cause a segmentation fault instead of
generating the error EINVAL.
io_cancel(2), io_destroy(2), io_setup(2), io_submit(2),
timespec(3), aio(7), time(7)
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-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 io_getevents(2)
Pages that refer to this page: io_cancel(2), io_destroy(2), io_setup(2), io_submit(2), syscalls(2), aio(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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