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AIO_CANCEL(2)               BSD System Calls Manual              AIO_CANCEL(2)

     aio_cancel -- cancel an outstanding asynchronous I/O operation (REALTIME)

     Standard C Library (libc, -lc)

     #include <aio.h>

     aio_cancel(int fildes, struct aiocb *aiocbp);

     The aio_cancel() system call cancels the outstanding asynchronous I/O request for the file descriptor
     specified in fildes.  If aiocbp is specified, only that specific asynchronous I/O request is cancelled.

     Normal asynchronous notification occurs for cancelled requests.  Requests complete with an error result
     of ECANCELED.

     The aio_cancel() system call does not cancel asynchronous I/O requests for raw disk devices.  The
     aio_cancel() system call will always return AIO_NOTCANCELED for file descriptors associated with raw
     disk devices.

     The aio_cancel() system call returns -1 to indicate an error, or one of the following:

                   All of the requests meeting the criteria have finished.

                   All outstanding requests meeting the criteria specified were cancelled.

                   Some requests were not cancelled, status for the requests should be checked with

     An error return from aio_cancel() indicates:

     [EBADF]            The fildes argument is not a valid file descriptor.

     aio_error(2), aio_read(2), aio_return(2), aio_suspend(2), aio_write(2), aio(4)

     The aio_cancel() system call is expected to conform to the IEEE Std 1003.1 (``POSIX.1'') standard.

     The aio_cancel() system call first appeared in FreeBSD 3.0.  The first functional implementation of
     aio_cancel() appeared in FreeBSD 4.0.

     This manual page was originally written by Wes Peters <>.  Christopher M Sedore
     <> updated it when aio_cancel() was implemented for FreeBSD 4.0.

BSD                            January 19, 2000                            BSD

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