FCHMODAT(2) Linux Programmer's Manual FCHMODAT(2)
fchmodat - change permissions of a file relative to a directory file descriptor
#include <fcntl.h> /* Definition of AT_* constants */
int fchmodat(int dirfd, const char *pathname, mode_t mode, int flags);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.10:
_XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
The fchmodat() system call operates in exactly the same way as chmod(2), except for the
differences described in this manual page.
If the pathname given in pathname is relative, then it is interpreted relative to the
directory referred to by the file descriptor dirfd (rather than relative to the current
working directory of the calling process, as is done by chmod(2) for a relative pathname).
If pathname is relative and dirfd is the special value AT_FDCWD, then pathname is inter-
preted relative to the current working directory of the calling process (like chmod(2)).
If pathname is absolute, then dirfd is ignored.
flags can either be 0, or include the following flag:
If pathname is a symbolic link, do not dereference it: instead operate on the link
itself. This flag is not currently implemented.
On success, fchmodat() returns 0. On error, -1 is returned and errno is set to indicate
The same errors that occur for chmod(2) can also occur for fchmodat(). The following
additional errors can occur for fchmodat():
EBADF dirfd is not a valid file descriptor.
EINVAL Invalid flag specified in flags.
pathname is relative and dirfd is a file descriptor referring to a file other than
flags specified AT_SYMLINK_NOFOLLOW, which is not supported.
fchmodat() was added to Linux in kernel 2.6.16; library support was added to glibc in ver-
See openat(2) for an explanation of the need for fchmodat().
The GNU C library wrapper function implements the POSIX-specified interface described in
this page. This interface differs from the underlying Linux system call, which does not
have a flags argument.
chmod(2), openat(2), path_resolution(7), symlink(7)
This page is part of release 3.53 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
Linux 2012-05-22 FCHMODAT(2)