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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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FUTEX_FD(2const) FUTEX_FD(2const)
FUTEX_FD - create a file descriptor associated with a futex
Standard C library (libc, -lc)
#include <linux/futex.h> /* Definition of FUTEX_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
[[deprecated]]
long syscall(SYS_futex, uint32_t *uaddr, FUTEX_FD, uint32_t val);
This operation creates a file descriptor that is associated with
the futex at uaddr. The caller must close the returned file
descriptor after use.
When another process or thread performs a FUTEX_WAKE(2const) on
the futex word, the file descriptor indicates as being readable
with select(2), poll(2), and epoll(7)
The file descriptor can be used to obtain asynchronous
notifications: if val is nonzero, then, when another process or
thread executes a FUTEX_WAKE(2const), the caller will receive the
signal number that was passed in val.
On error, -1 is returned, and errno is set to indicate the error.
On success, FUTEX_FD Returns the new file descriptor associated
with the futex.
See futex(2).
EINVAL The signal number supplied in val is invalid.
ENFILE The system-wide limit on the total number of open files has
been reached.
Linux.
From Linux 2.6.0 up to and including Linux 2.6.25.
Because it was inherently racy, FUTEX_FD has been removed from
Linux 2.6.26 onward.
futex(2)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
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⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
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2025-08-11. If you discover any rendering problems in this HTML
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Linux man-pages 6.15 2025-05-30 FUTEX_FD(2const)
Pages that refer to this page: futex(2)
Copyright and license for this manual page
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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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