fchown(2)                      DG/UX R4.11MU05                     fchown(2)


NAME
       fchown - change user id and group id of a file

SYNOPSIS
       #include <unistd.h>

       int  fchown (fildes, user, group)
       int  fildes;
       int  user;
       int  group;

DESCRIPTION
       Use fchown to set the access of a file:

        fildes is a valid, active descriptor for an open file of type
               ordinary, directory, block special, block character, or
               symbolic link.  The file must reside on a file system device
               mounted read-write.

        user   is the new user id (st_uid) for the file. A value of -1
               leaves the user id unchanged.

        group  is the new group id (st_gid) for the file. A value of -1
               leaves the group id unchanged.

       If the call succeeds, the file's time of last attribute change
       (st_ctime) is set to the current time. If the call fails, the user
       id, group id, and attributes of the file remain unchanged.

ACCESS CONTROL
       The calling process must have appropriate privilege or the effective
       user id of the calling process must match the file's user id.  For
       systems supporting the DG/UX Capability Option, appropriate privilege
       is defined as having one or more specific capabilities enabled in the
       effective capability set of the calling process.  See cap_defaults(5)
       for the default capability for this system call.

       On systems without the DG/UX Capability Option, appropriate privilege
       means that the process has an effective UID of root.  See the
       appropriate_privilege(5) man page for more information.

       When customizing the DG/UX system, the installer or administrator may
       restrict access to any file. Use of fchown(2) with a restricted file
       is limited as follows: (1) only a user with the appropriate privilege
       can modify a restricted file's user id; (2) a process whose effective
       user ID matches the user ID of the file may change the group ID, but
       only to the process's effective group ID, or to one of the process's
       supplementary IDs.  To find out whether access to a file is
       restricted, use pathconf(2) with the _PC_CHOWN_RESTRICTED argument.

RETURN VALUE
       0      The user id and group id of the file were successfully
              changed.

       -1     An error occurred.  errno is set to indicate the error.

DIAGNOSTICS
       Errno may be set to one of the following error codes:

       EBADF     The descriptor does not refer to an open file.

       EINVAL    The descriptor refers to a pipe or an object that is not a
                 file.

       EPERM     Permission to change the file's user and group ids is
                 denied.

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

SEE ALSO
       chgrp(1), chmod(1), chown(1), chmod(2), chown(2), fchmod(2),
       appropriate_privilege(5).
       cap_defaults(5).


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