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fchmodat - change permissions of a file relative to a directory file
#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 interpreted 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
On success, fchmodat() returns 0. On error, -1 is returned and errno
is set to indicate the error.
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 a directory.
flags specified AT_SYMLINK_NOFOLLOW, which is not supported.
fchmodat() was added to Linux in kernel 2.6.16.
See openat(2) for an explanation of the need for fchmodat().
chmod(2), openat(2), path_resolution(7), symlink(7)
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