FCHMOD(3)                  POSIX Programmer's Manual                 FCHMOD(3)



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

NAME
       fchmod -- change mode of a file

SYNOPSIS
       #include <sys/stat.h>

       int fchmod(int fildes, mode_t mode);

DESCRIPTION
       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.

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

ERRORS
       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.

       The following sections are informative.

EXAMPLES
   Changing the Current Permissions for aa File
       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);

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

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

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

COPYRIGHT
       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(3)
