fchmod

SYNOPSIS
       #include <sys/stat.h>

       int chmod(const char *path, mode_t mode);
       int fchmod(int fd, mode_t mode);

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

       fchmod(): _BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION
       These  system calls change the permissions of a file.  They differ only
       in how the file is specified:

       * chmod() changes the permissions of the file specified whose  pathname
         is given in path, which is dereferenced if it is a symbolic link.

       * fchmod()  changes the permissions of the file referred to by the open
         file descriptor fd.

       The new file permissions are specified in mode, which  is  a  bit  mask
       created by ORing together zero or more of the following:

       S_ISUID  (04000)  set-user-ID   (set   process  effective  user  ID  on
                         execve(2))

       S_ISGID  (02000)  set-group-ID  (set  process  effective  group  ID  on
                         execve(2);   mandatory   locking,   as  described  in
                         fcntl(2); take a new file's group from parent  direc-
                         tory, as described in chown(2) and mkdir(2))

       S_ISVTX  (01000)  sticky bit (restricted deletion flag, as described in
                         unlink(2))

       S_IRUSR  (00400)  read by owner

       S_IWUSR  (00200)  write by owner

       S_IXUSR  (00100)  execute/search by owner ("search" applies for  direc-
                         tories,  and  means that entries within the directory
                         can be accessed)

       S_IRGRP  (00040)  read by group

       S_IWGRP  (00020)  write by group

       S_IXGRP  (00010)  execute/search by group

       S_IROTH  (00004)  read by others

       S_IWOTH  (00002)  write by others

       S_IXOTH  (00001)  execute/search by others
       and set-group-ID execution bits may be turned off if a file is written.
       (On Linux this  occurs  if  the  writing  process  does  not  have  the
       CAP_FSETID  capability.)   On some file systems, only the superuser can
       set the sticky bit, which may have a special meaning.  For  the  sticky
       bit,  and  for  set-user-ID  and  set-group-ID bits on directories, see
       stat(2).

       On NFS file  systems,  restricting  the  permissions  will  immediately
       influence already open files, because the access control is done on the
       server, but open files are maintained by the client.  Widening the per-
       missions  may  be  delayed  for  other  clients if attribute caching is
       enabled on them.

RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and  errno  is
       set appropriately.

ERRORS
       Depending  on  the file system, other errors can be returned.  The more
       general errors for chmod() are listed below:

       EACCES Search permission is denied on a component of the  path  prefix.
              (See also path_resolution(7).)

       EFAULT path points outside your accessible address space.

       EIO    An I/O error occurred.

       ELOOP  Too many symbolic links were encountered in resolving path.

       ENAMETOOLONG
              path is too long.

       ENOENT The file does not exist.

       ENOMEM Insufficient kernel memory was available.

       ENOTDIR
              A component of the path prefix is not a directory.

       EPERM  The  effective UID does not match the owner of the file, and the
              process  is  not  privileged  (Linux:  it  does  not  have   the
              CAP_FOWNER capability).

       EROFS  The named file resides on a read-only file system.

       The general errors for fchmod() are listed below:

       EBADF  The file descriptor fd is not valid.

       EIO    See above.

       EPERM  See above.




Linux                             2008-05-26                          CHMOD(2)