F_GETFL(2const) — Linux manual page

F_GETFL(2const)                                           F_GETFL(2const)

NAME         top

       F_GETFL, F_SETFL - get/set file status flags

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <fcntl.h>

       int fcntl(int fd, F_GETFL);
       int fcntl(int fd, F_SETFL, int arg);

DESCRIPTION         top

       Each open file description has certain associated status flags,
       initialized by open(2) and possibly modified by fcntl(2).
       Duplicated file descriptors (made with dup(2), F_DUPFD(2const),
       fork(2), etc.) refer to the same open file description, and thus
       share the same file status flags.

       The file status flags and their semantics are described in
       open(2).

       F_GETFL
              Return (as the function result) the file access mode and
              the file status flags; arg is ignored.

       F_SETFL
              Set the file status flags to the value specified by arg.
              File access mode (O_RDONLY, O_WRONLY, O_RDWR) and file
              creation flags (i.e., O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC)
              in arg are ignored.  On Linux, this operation can change
              only the O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME, and
              O_NONBLOCK flags.  It is not possible to change the O_DSYNC
              and O_SYNC flags; see BUGS, below.

RETURN VALUE         top

       F_GETFL
              Value of file status flags.

       F_SETFL
              Zero.

       On error, -1 is returned, and errno is set to indicate the error.

ERRORS         top

       See fcntl(2).

       EPERM  Attempted to clear the O_APPEND flag on a file that has the
              append-only attribute set.

STANDARDS         top

       POSIX.1-2008.

HISTORY         top

       SVr4, 4.3BSD, POSIX.1-2001.

BUGS         top

   F_SETFL
       It is not possible to use F_SETFL to change the state of the
       O_DSYNC and O_SYNC flags.  Attempts to change the state of these
       flags are silently ignored.

SEE ALSO         top

       fcntl(2), open(2)

COLOPHON         top

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Linux man-pages 6.15            2025-07-20                F_GETFL(2const)

Pages that refer to this page: fcntl(2),  F_GETSIG(2const)

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