38065bce20
high-order bit set", as this error is obsolete. Eventually we may want to add code to some of the "optional" filesystems (msdosfs, etc.) that checks for illegal characters. At that time it would be appropriate to reintroduce this error with appropriate text. Perhaps "The pathname contains a character that is not valid for filesystem type".
187 lines
5.8 KiB
Groff
187 lines
5.8 KiB
Groff
.\" Copyright (c) 1980, 1991 Regents of the University of California.
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.\" 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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. 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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.\" from: @(#)chmod.2 6.6 (Berkeley) 3/10/91
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.\" $Id: chmod.2,v 1.6 1994/04/22 00:13:29 jtc Exp $
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.\"
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.Dd March 10, 1991
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.Dt CHMOD 2
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.Os BSD 4
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.Sh NAME
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.Nm chmod ,
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.Nm fchmod
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.Nd change mode of file
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/stat.h>
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.Ft int
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.Fn chmod "const char *path" "mode_t mode"
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.Ft int
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.Fn fchmod "int fd" "mode_t mode"
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.Sh DESCRIPTION
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The function
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.Fn chmod
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sets the file permission bits
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of the file
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specified by the pathname
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.Fa path
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to
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.Fa mode .
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.Fn Fchmod
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sets the permission bits of the specified
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file descriptor
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.Fa fd .
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.Fn Chmod
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verifies that the process owner (user) either owns
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the file specified by
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.Fa path
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(or
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.Fa fd ) ,
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or
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is the super-user.
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A mode is created from
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.Em or Ap d
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permission bit masks
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defined in
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.Aq Pa sys/stat.h :
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.Bd -literal -offset indent -compact
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#define S_IRWXU 0000700 /* RWX mask for owner */
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#define S_IRUSR 0000400 /* R for owner */
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#define S_IWUSR 0000200 /* W for owner */
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#define S_IXUSR 0000100 /* X for owner */
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#define S_IRWXG 0000070 /* RWX mask for group */
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#define S_IRGRP 0000040 /* R for group */
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#define S_IWGRP 0000020 /* W for group */
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#define S_IXGRP 0000010 /* X for group */
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#define S_IRWXO 0000007 /* RWX mask for other */
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#define S_IROTH 0000004 /* R for other */
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#define S_IWOTH 0000002 /* W for other */
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#define S_IXOTH 0000001 /* X for other */
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#define S_ISUID 0004000 /* set user id on execution */
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#define S_ISGID 0002000 /* set group id on execution */
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#define S_ISVTX 0001000 /* save swapped text even after use */
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.Ed
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.Pp
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The
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.Dv ISVTX
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(the
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.Em sticky bit )
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indicates to the system which executable files are shareable (the
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default) and the system maintains the program text of the files
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in the swap area. The sticky bit may only be set by the super user
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on shareable executable files.
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.Pp
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If mode
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.Dv ISVTX
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(the `sticky bit') is set on a directory,
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an unprivileged user may not delete or rename
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files of other users in that directory. The sticky bit may be
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set by any user on a directory which the user owns or has appropriate
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permissions.
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For more details of the properties of the sticky bit, see
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.Xr sticky 8 .
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.Pp
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Writing or changing the owner of a file
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turns off the set-user-id and set-group-id bits
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unless the user is the super-user.
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This makes the system somewhat more secure
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by protecting set-user-id (set-group-id) files
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from remaining set-user-id (set-group-id) if they are modified,
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at the expense of a degree of compatibility.
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.Sh RETURN VALUES
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Upon successful completion, a value of 0 is returned.
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Otherwise, a value of -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Fn Chmod
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will fail and the file mode 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 does not match the owner of the file and
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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 Fchmod
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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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The descriptor is not valid.
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.It Bq Er EINVAL
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.Fa Fd
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refers to a socket, not to a file.
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.It Bq Er EROFS
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The 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 chmod 1 ,
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.Xr open 2 ,
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.Xr chown 2 ,
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.Xr stat 2 ,
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.Xr sticky 8
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.Sh STANDARDS
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The
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.Fn chmod
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function is expected to conform to
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.St -p1003.1-88 .
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.Sh HISTORY
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The
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.Fn fchmod
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function call
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appeared in
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.Bx 4.2 .
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