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F_GETPIPE_SZ(2const) — Linux manual page

F_GETPIPE_SZ(2const)F_GETPIPE_SZ(2const)

NAME        top

       F_GETPIPE_SZ, F_SETPIPE_SZ - get/set the capacity of a pipe

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#define _GNU_SOURCE#include <fcntl.h>int fcntl(intfd, F_SETPIPE_SZ, intarg);int fcntl(intfd, F_GETPIPE_SZ);

DESCRIPTION        top

F_SETPIPE_SZ              Change the capacity of the pipe referred to byfd to be at              leastarg bytes.  An unprivileged process can adjust the              pipe capacity to any value between the system page size and              the limit defined in/proc/sys/fs/pipe-max-size (seeproc_sys_fs(5)).  Attempts to set the pipe capacity below              the page size are silently rounded up to the page size.              Attempts by an unprivileged process to set the pipe              capacity above the limit in/proc/sys/fs/pipe-max-size              yield the errorEPERM; a privileged process              (CAP_SYS_RESOURCE) can override the limit.              When allocating the buffer for the pipe, the kernel may use              a capacity larger thanarg, if that is convenient for the              implementation.  (In the current implementation, the              allocation is the next higher power-of-two page-size              multiple of the requested size.)  The actual capacity (in              bytes) that is set is returned as the function result.              Attempting to set the pipe capacity smaller than the amount              of buffer space currently used to store data produces the              errorEBUSY.              Note that because of the way the pages of the pipe buffer              are employed when data is written to the pipe, the number              of bytes that can be written may be less than the nominal              size, depending on the size of the writes.F_GETPIPE_SZ              Return (as the function result) the capacity of the pipe              referred to byfd.

RETURN VALUE        top

       The pipe capacity.       On error, -1 is returned, anderrno is set to indicate the error.

ERRORS        top

       Seefcntl(2).EBUSYop isF_SETPIPE_SZand the new pipe capacity specified inarg is smaller than the amount of buffer space currently              used to store data in the pipe.EPERMop isF_SETPIPE_SZand the soft or hard user pipe limit has              been reached; seepipe(7).

STANDARDS        top

       Linux.

HISTORY        top

       Linux 2.6.35.

SEE ALSO        top

fcntl(2)

COLOPHON        top

       This page is part of theman-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 isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-07-20F_GETPIPE_SZ(2const)

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