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a different file than the a.out hints, namely, "/var/run/ld-elf.so.hints".
These hints consist only of the directory search path. There is
no hash table as in the a.out hints, because ELF doesn't have to
search for the file with the highest minor version number. (It
doesn't have minor version numbers at all.)
A single run of ldconfig updates either the a.out hints or the ELF
hints, but not both. The set of hints to process is selected in
the usual way, via /etc/objformat, or ${OBJFORMAT}, or the "-aout"
or "-elf" command line option. The rationale is that you probably
want to search different directories for ELF than for a.out.
"ldconfig -r" is faked up to produce output like we are used to,
except that for ELF there are no minor version numbers. This should
enable "ldconfig -r" to be used for checking LIB_DEPENDS in ports
even for ELF.
I implemented the ELF functionality in a new source file, with an
eye toward eliminating the a.out code entirely at some point in
the future.
180 lines
6.0 KiB
Groff
180 lines
6.0 KiB
Groff
.\"
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.\" Copyright (c) 1993 Paul Kranenburg
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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 Paul Kranenburg.
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.\" 3. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $Id: ldconfig.8,v 1.15 1998/01/01 02:31:47 alex Exp $
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.\"
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.Dd October 3, 1993
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.Dt LDCONFIG 8
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.Os FreeBSD
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.Sh NAME
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.Nm ldconfig
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.Nd configure the shared library cache
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.Sh SYNOPSIS
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.Nm ldconfig
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.Op Fl aout | Fl elf
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.Op Fl Rmrsv
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.Op Fl f Ar hints_file
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.Op Ar directory | file Ar ...
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.Sh DESCRIPTION
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.Nm
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is used to prepare a set of
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.Dq hints
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for use by the dynamic linker
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to facilitate quick lookup of shared libraries available in multiple
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directories. It scans a set of built-in system directories and any
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.Ar directories
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specified on the command line (in the given order) looking for
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shared libraries and stores the results in a system file to forestall
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the overhead that would otherwise result from the directory search
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operations the dynamic linker would have to perform to load the
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required shared libraries.
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.Pp
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Files named on the command line are expected to contain directories
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to scan for shared libraries. Each directory's pathname must start on a new
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line. Blank lines and lines starting with the comment character
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.Ql \&#
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are ignored.
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.Pp
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The shared libraries so found will be automatically available for loading
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if needed by the program being prepared for execution. This obviates the need
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for storing search paths within the executable.
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.Pp
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The
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.Ev LD_LIBRARY_PATH
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environment variable can be used to override the use of
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directories (or the order thereof) from the cache or to specify additional
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directories where shared libraries might be found.
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.Ev LD_LIBRARY_PATH
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is a
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.Sq \:
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separated list of directory paths which are searched by
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the dynamic linker
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when it needs to load a shared library. It can be viewed as the run-time
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equivalent of the
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.Fl L
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switch of
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.Xr ld 1 .
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.Pp
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.Nm Ldconfig
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is typically run as part of the boot sequence.
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.Pp
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The following options recognized by
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.Nm ldconfig:
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.Bl -tag -width indent
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.It Fl aout
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Generate the hints for a.out format shared libraries.
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.It Fl elf
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Generate the hints for ELF format shared libraries.
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.It Fl R
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Rescan the previously configured directories. This opens the previous hints
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file and fetches the directory list from the header. Any additional pathnames
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on the command line are also processed.
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.It Fl f Ar hints_file
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Read and/or update the specified hints file, instead of the standard file.
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This option is provided primarily for testing.
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.It Fl m
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Instead of replacing the contents of the hints file
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with those found in the directories specified,
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.Dq merge
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in new entries.
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Directories recorded in the hints file by previous runs of
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.Nm
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are also rescanned for new shared libraries.
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.It Fl r
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List the current contents of the hints file
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on the standard output. The hints file is not modified. The list of
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directories stored in the hints file is included.
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.It Fl s
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Do not scan the built-in system directory
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.Pq Dq /usr/lib
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for shared libraries.
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.It Fl v
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Switch on verbose mode.
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.Sh Security
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Special care must be taken when loading shared libraries into the address
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space of
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.Ev set-user-Id
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programs. Whenever such a program is run,
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the dynamic linker
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will only load shared libraries from the hints
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file. In particular, the
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.Ev LD_LIBRARY_PATH
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is not used to search for libraries. Thus, the role of ldconfig is dual. In
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addition to building a set of hints for quick lookup, it also serves to
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specify the trusted collection of directories from which shared objects can
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be safely loaded. It is presumed that the set of directories specified to
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.Nm ldconfig
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are under control of the system's administrator.
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.Sh ENVIRONMENT
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.Bl -tag -width OBJFORMATxxx -compact
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.It Ev OBJFORMAT
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Overrides
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.Pa /etc/objformat
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(see below) to determine whether
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.Fl aout
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or
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.Fl elf
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is the default. If set, its value should be either
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.Ql aout
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or
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.Ql elf .
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.El
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.Sh FILES
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.Bl -tag -width /var/run/ld-elf.so.hintsxxx -compact
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.It Pa /var/run/ld.so.hints
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Standard hints file for the a.out dynamic linker.
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.It Pa /var/run/ld-elf.so.hints
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Standard hints file for the ELF dynamic linker.
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.It Pa /etc/ld.so.conf
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Conventional configuration file containing directory names for
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invocations with
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.Fl aout .
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.It Pa /etc/ld-elf.so.conf
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Conventional configuration file containing directory names for
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invocations with
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.Fl elf .
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.It Pa /etc/objformat
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Determines whether
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.Fl aout
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or
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.Fl elf
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is the default. If present, it must consist of a single line
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containing either
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.Ql OBJFORMAT=aout
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or
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.Ql OBJFORMAT=elf .
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.Sh SEE ALSO
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.Xr ld 1 ,
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.Xr link 5
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.Sh HISTORY
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A
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.Nm
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utility first appeared in SunOS 4.0, it appeared in its current form
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in FreeBSD 1.1.
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