215 lines
5.5 KiB
Groff
215 lines
5.5 KiB
Groff
.\" $NetBSD: chown.2,v 1.30 2004/05/13 10:20:57 wiz Exp $
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.\"
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.\" Copyright (c) 1980, 1991, 1993, 1994
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)chown.2 8.4 (Berkeley) 4/19/94
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.\"
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.Dd April 19, 1994
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.Dt CHOWN 2
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.Os
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.Sh NAME
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.Nm chown ,
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.Nm lchown ,
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.Nm fchown
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.Nd change owner and group of a file
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft int
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.Fn chown "const char *path" "uid_t owner" "gid_t group"
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.Ft int
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.Fn lchown "const char *path" "uid_t owner" "gid_t group"
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.Ft int
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.Fn fchown "int fd" "uid_t owner" "gid_t group"
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.Sh DESCRIPTION
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The owner ID and group ID of the file
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named by
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.Fa path
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or referenced by
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.Fa fd
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is changed as specified by the arguments
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.Fa owner
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and
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.Fa group .
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The owner of a file may change the
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.Fa group
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to a group of which
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he or she is a member,
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but the change
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.Fa owner
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capability is restricted to the super-user.
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.Pp
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When called to change the owner of a file,
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.Fn chown ,
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.Fn lchown
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and
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.Fn fchown
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clear the set-user-id
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.Dv ( S_ISUID )
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bit on the file.
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When a called to change the group of a file,
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.Fn chown ,
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.Fn lchown
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and
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.Fn fchown
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clear the set-group-id
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.Dv ( S_ISGID )
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bit on the file.
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These actions are taken to prevent accidental or mischievous creation of
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set-user-id and set-group-id programs.
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.Pp
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.Fn lchown
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is like
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.Fn chown
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except in the case where the named file is a symbolic link,
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in which case
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.Fn lchown
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changes the owner and group of the link,
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while
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.Fn chown
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changes the owner and group of the file the link references.
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.Pp
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.Fn fchown
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is particularly useful when used in conjunction
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with the file locking primitives (see
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.Xr flock 2 ) .
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.Pp
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One of the owner or group id's
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may be left unchanged by specifying it as (uid_t)\-1 or (gid_t)\-1 respectively.
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.Sh RETURN VALUES
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Zero is returned if the operation was successful;
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\-1 is returned if an error occurs, with a more specific
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error code being placed in the global variable
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.Va errno .
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.Sh ERRORS
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.Fn chown
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and
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.Fn lchown
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will fail and the file will be unchanged if:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded
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.Dv {NAME_MAX}
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characters, or an entire path name exceeded
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.Dv {PATH_MAX}
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characters.
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.It Bq Er ENOENT
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The named file does not exist.
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er EPERM
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The effective user ID is not the super-user.
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.It Bq Er EROFS
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The named file resides on a read-only file system.
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.It Bq Er EFAULT
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.Fa path
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points outside the process's allocated address space.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.El
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.Pp
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.Fn fchown
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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.Fa fd
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does not refer to a valid descriptor.
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.It Bq Er EINVAL
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.Fa fd
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refers to a socket, not a file.
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.It Bq Er EPERM
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The effective user ID is not the super-user.
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.It Bq Er EROFS
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The named file resides on a read-only file system.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.El
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.Sh SEE ALSO
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.Xr chgrp 1 ,
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.Xr chmod 2 ,
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.Xr flock 2 ,
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.Xr symlink 7 ,
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.Xr chown 8
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.Sh STANDARDS
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The
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.Fn chown
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function deviates from the semantics defined in
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.St -p1003.1-90 ,
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which specifies that, unless the caller is the super-user, both the
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set-user-id and set-group-id bits on a file shall be cleared, regardless
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of the file attribute changed.
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The
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.Fn lchown
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and
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.Fn fchown
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functions, as defined by
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.St -xpg4.2 ,
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provide the same semantics.
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.Pp
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To retain conformance to these standards, compatibility interfaces
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are provided by the
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.Lb libposix
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as follows:
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.Bl -bullet -compact
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.It
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The
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.Fn chown
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function conforms to
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.St -p1003.1-90
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and
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.St -xpg4.2 .
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.It
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The
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.Fn lchown
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and
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.Fn fchown
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functions conform to
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.St -xpg4.2 .
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.El
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.Sh HISTORY
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The
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.Fn fchown
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function call appeared in
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.Bx 4.2 .
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.Pp
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The
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.Fn chown
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and
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.Fn fchown
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functions were changed to follow symbolic links in
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.Bx 4.4 .
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The
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.Fn lchown
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function call appeared in
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.Nx 1.3 .
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