.TH CHOWN 2
.CT 2 file_inq_creat dirs secur
.SH NAME
chown, fchown \(mi change owner and group of a file
.SH SYNOPSIS
.nf
.B int chown(name, owner, group)
.B char *name;
.PP
.B int fchown(fd, owner, group)
.fi
.SH DESCRIPTION
.I Chown
changes the
.I owner
and
.I group
of the file specified by the null-terminated string
.IR name .
.I Fchown
changes the owner and group of an open file
specified by file descriptor.
Only the super-user may
change the userid of a file.
The owner of a file
may change its groupid
to match the current effective groupid;
any other changes
are restricted to the super-user.
If the file has either
set-userid or set-groupid permission (see
.IR stat (2))
neither the userid or groupid may be changed.
.SH EXAMPLES
The following sequence, executed by a superuser process with
.BR T_NOCHK 
and
.B T_SETPRIV
capabilities, will change the owner of any file, regardless of
privileges and set-id modes
(less Herculean methods usually suffice).
The sequence is illustrative only: it ignores the
possiblility of the file being altered by a hostile superuser
while the file is unprivileged.
Sound security procedures might require the various steps to be done by
different persons, with interspersed vetting similar to that described in
.IR setpriv (8).
.IP
.EX
getflab(file, &savlab);
setflab(file, &nopriv);
stat(file, &savmod);
chmod(file, 0);
chown(file, uid, gid);
chmod(file, savmod.s_mode);
setflab(file, &savlab);
.EE
.SH "SEE ALSO"
.IR chown (8), 
.IR chmod (2), 
.IR passwd (5)
.SH DIAGNOSTICS
.BR EACCES ,
.BR EBADF ,
.BR EFAULT ,
.BR EIO ,
.BR ELAB ,
.BR ELOOP ,
.BR ENOENT ,
.BR ENOTDIR ,
.BR EPERM