This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE  and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                        FCHMOD(3POSIX)

       The  fchmod()  function shall be equivalent to chmod() except that the file whose permissions are changed
       is specified by the file descriptor fildes.

       If fildes references a shared memory object, the fchmod() function need only affect the S_IRUSR, S_IWUSR,
       S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH file permission bits.

       If fildes references a typed memory object, the behavior of fchmod() is unspecified.

       If fildes refers to a socket, the behavior of fchmod() is unspecified.

       If fildes refers to a STREAM (which is fattach()-ed into the file system name  space)  the  call  returns
       successfully, doing nothing.

       The fchmod() function shall fail if:

       EBADF  The fildes argument is not an open file descriptor.

       EPERM  The effective user ID does not match the  owner  of  the  file  and  the  process  does  not  have
              appropriate privileges.

       EROFS  The file referred to by fildes resides on a read-only file system.

       The fchmod() function may fail if:

       EINTR  The fchmod() function was interrupted by a signal.

       EINVAL The value of the mode argument is invalid.

       EINVAL The  fildes  argument refers to a pipe and the implementation disallows execution of fchmod() on a
              pipe.

       Thefollowingsectionsareinformative.

ChangingtheCurrentPermissionsforaFile
       The following example shows how to change the permissions for a file named  /home/cnd/mod1  so  that  the
       owner and group have read/write/execute permissions, but the world only has read/write permissions.

           #include <sys/stat.h>
           #include <fcntl.h>

           mode_t mode;
           int    fildes;
           ...
           fildes = open("/home/cnd/mod1", O_RDWR);
           fchmod(fildes, S_IRWXU | S_IRWXG | S_IROTH | S_IWOTH);

       None.

       fchmod — change mode of a file

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       None.

       Upon  successful  completion,  fchmod()  shall  return  0. Otherwise, it shall return -1 and set errno to
       indicate the error.

chmod(), chown(), creat(), fcntl(), fstatat(), fstatvfs(), mknod(), open(), read(), write()

       The Base Definitions volume of POSIX.1‐2017, <sys_stat.h>

       #include <sys/stat.h>

       int fchmod(int fildes, mode_t mode);