NAME

       fchmodat - change permissions of a file relative to a directory file descriptor

SYNOPSIS

       #include <fcntl.h>           /* Definition of AT_* constants */
       #include <sys/stat.h>

       int fchmodat(int dirfd, const char *pathname, mode_t mode, int flags);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       fchmodat():
           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _ATFILE_SOURCE

DESCRIPTION

       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:

       AT_SYMLINK_NOFOLLOW
              If pathname is a symbolic link, do not dereference it: instead operate on the  link
              itself.  This flag is not currently implemented.

RETURN VALUE

       On  success,  fchmodat() returns 0.  On error, -1 is returned and errno is set to indicate
       the error.

ERRORS

       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.

       ENOTDIR
              pathname  is relative and dirfd is a file descriptor referring to a file other than
              a directory.

       ENOTSUP
              flags specified AT_SYMLINK_NOFOLLOW, which is not supported.

VERSIONS

       fchmodat() was added to Linux in kernel 2.6.16; library support  was  added  to  glibc  in
       version 2.4.

CONFORMING TO

       POSIX.1-2008.

NOTES

       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.

SEE ALSO

       chmod(2), openat(2), path_resolution(7), symlink(7)

COLOPHON

       This  page  is  part of release 3.54 of the Linux man-pages project.  A description of the
       project,    and    information    about    reporting    bugs,    can    be    found     at
       http://www.kernel.org/doc/man-pages/.