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+.\" Copyright (c) 1980, 1991, 1993, 1994
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)chown.2	8.4 (Berkeley) 4/19/94
+.\" $FreeBSD$
+.\"
+.Dd April 10, 2008
+.Dt CHOWN 2
+.Os
+.Sh NAME
+.Nm chown ,
+.Nm fchown ,
+.Nm lchown ,
+.Nm fchownat
+.Nd change owner and group of a file
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In unistd.h
+.Ft int
+.Fn chown "const char *path" "uid_t owner" "gid_t group"
+.Ft int
+.Fn fchown "int fd" "uid_t owner" "gid_t group"
+.Ft int
+.Fn lchown "const char *path" "uid_t owner" "gid_t group"
+.Ft int
+.Fn fchownat "int fd" "const char *path" "uid_t owner" "gid_t group" "int flag"
+.Sh DESCRIPTION
+The owner ID and group ID of the file
+named by
+.Fa path
+or referenced by
+.Fa fd
+is changed as specified by the arguments
+.Fa owner
+and
+.Fa group .
+The owner of a file may change the
+.Fa group
+to a group of which
+he or she is a member,
+but the change
+.Fa owner
+capability is restricted to the super-user.
+.Pp
+The
+.Fn chown
+system call
+clears the set-user-id and set-group-id bits
+on the file
+to prevent accidental or mischievous creation of
+set-user-id and set-group-id programs if not executed
+by the super-user.
+The
+.Fn chown
+system call
+follows symbolic links to operate on the target of the link
+rather than the link itself.
+.Pp
+The
+.Fn fchown
+system call
+is particularly useful when used in conjunction
+with the file locking primitives (see
+.Xr flock 2 ) .
+.Pp
+The
+.Fn lchown
+system call is similar to
+.Fn chown
+but does not follow symbolic links.
+.Pp
+The
+.Fn fchownat
+system call is equivalent to the
+.Fn chown
+and
+.Fn lchown
+except in the case where
+.Fa path
+specifies a relative path.
+In this case the file to be changed is determined relative to the directory
+associated with the file descriptor
+.Fa fd
+instead of the current working directory.
+.Pp
+Values for
+.Fa flag
+are constructed by a bitwise-inclusive OR of flags from the following
+list, defined in
+.In fcntl.h :
+.Bl -tag -width indent
+.It Dv AT_SYMLINK_NOFOLLOW
+If
+.Fa path
+names a symbolic link, ownership of the symbolic link is changed.
+.El
+.Pp
+If
+.Fn fchownat
+is passed the special value
+.Dv AT_FDCWD
+in the
+.Fa fd
+parameter, the current working directory is used and the behavior is identical
+to a call to
+.Fn chown
+or
+.Fn lchown
+respectively, depending on whether or not the
+.Dv AT_SYMLINK_NOFOLLOW
+bit is set in the
+.Fa flag
+argument.
+.Pp
+One of the owner or group id's
+may be left unchanged by specifying it as -1.
+.Sh RETURN VALUES
+.Rv -std
+.Sh ERRORS
+The
+.Fn chown
+and
+.Fn lchown
+will fail and the file will be unchanged if:
+.Bl -tag -width Er
+.It Bq Er ENOTDIR
+A component of the path prefix is not a directory.
+.It Bq Er ENAMETOOLONG
+A component of a pathname exceeded 255 characters,
+or an entire path name exceeded 1023 characters.
+.It Bq Er ENOENT
+The named file does not exist.
+.It Bq Er EACCES
+Search permission is denied for a component of the path prefix.
+.It Bq Er ELOOP
+Too many symbolic links were encountered in translating the pathname.
+.It Bq Er EPERM
+The operation would change the ownership, but the effective user ID is not the
+super-user.
+.It Bq Er EPERM
+The named file has its immutable or append-only flag set, see the
+.Xr chflags 2
+manual page for more information.
+.It Bq Er EROFS
+The named file resides on a read-only file system.
+.It Bq Er EFAULT
+The
+.Fa path
+argument
+points outside the process's allocated address space.
+.It Bq Er EIO
+An I/O error occurred while reading from or writing to the file system.
+.El
+.Pp
+The
+.Fn fchown
+system call will fail if:
+.Bl -tag -width Er
+.It Bq Er EBADF
+The
+.Fa fd
+argument
+does not refer to a valid descriptor.
+.It Bq Er EINVAL
+The
+.Fa fd
+argument
+refers to a socket, not a file.
+.It Bq Er EPERM
+The effective user ID is not the super-user.
+.It Bq Er EROFS
+The named file resides on a read-only file system.
+.It Bq Er EIO
+An I/O error occurred while reading from or writing to the file system.
+.El
+.Pp
+In addition to the errors specified for
+.Fn chown
+and
+.Fn lchown ,
+the
+.Fn fchownat
+system call may fail if:
+.Bl -tag -width Er
+.It Bq Er EBADF
+The
+.Fa path
+argument does not specify an absolute path and the
+.Fa fd
+argument is neither
+.Dv AT_FDCWD
+nor a valid file descriptor open for searching.
+.It Bq Er EINVAL
+The value of the
+.Fa flag
+argument is not valid.
+.It Bq Er ENOTDIR
+The
+.Fa path
+argument is not an absolute path and
+.Fa fd
+is neither
+.Dv AT_FDCWD
+nor a file descriptor associated with a directory.
+.El
+.Sh SEE ALSO
+.Xr chgrp 1 ,
+.Xr chflags 2 ,
+.Xr chmod 2 ,
+.Xr flock 2 ,
+.Xr chown 8
+.Sh STANDARDS
+The
+.Fn chown
+system call is expected to conform to
+.St -p1003.1-90 .
+The
+.Fn fchownat
+system call follows The Open Group Extended API Set 2 specification.
+.Sh HISTORY
+The
+.Fn chown
+function appeared in
+.At v7 .
+The
+.Fn fchown
+system call appeared in
+.Bx 4.2 .
+.Pp
+The
+.Fn chown
+system call was changed to follow symbolic links in
+.Bx 4.4 .
+The
+.Fn lchown
+system call was added in
+.Fx 3.0
+to compensate for the loss of functionality.
+.Pp
+The
+.Fn fchownat
+system call appeared in
+.Fx 8.0 .