F_GETFL(2const)                                                F_GETFL(2const)

NAME
       F_GETFL, F_SETFL - get/set file status flags

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <fcntl.h>

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

DESCRIPTION
       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
       F_GETFL
              Value of file status flags.

       F_SETFL
              Zero.

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

ERRORS
       See fcntl(2).

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

STANDARDS
       POSIX.1-2008.

HISTORY
       SVr4, 4.3BSD, POSIX.1-2001.

BUGS
   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
       fcntl(2), open(2)

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