256 lines
7.9 KiB
Text
256 lines
7.9 KiB
Text
This is the README for chrony.
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What is chrony?
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===============
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Chrony is a pair of programs for maintaining the accuracy of computer
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clocks.
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chronyd is a (background) daemon program that can be started at boot
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time. This does most of the work.
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chronyc is a command-line interface program which can be used to
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monitor chronyd's performance and to change various operating
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parateters whilst it is running.
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chronyd's main function is to obtain measurements of the true (UTC)
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time from one of several sources, and correct the system clock
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accordingly. It also works out the rate at which the system clock
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gains or loses time and uses this information to keep it accurate
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between measurements from the reference.
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The reference time can be derived from Network Time Protocol (NTP)
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servers, reference clocks, or wristwatch-and-keyboard (via chronyc).
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The main source of information about the Network Time Protocol is
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http://www.eecis.udel.edu/~ntp.
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It is designed so that it can work on computers which only have
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intermittent access to reference sources, for example computers which
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use a dial-up account to access the Internet. Of course, it will work
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on computers with permanent connections too.
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In addition, on Linux it can monitor the system's real time clock
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performance, so the system can maintain accurate time even across
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reboots.
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Typical accuracies available between 2 machines are
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On an ethernet LAN : 100-200 microseconds, often much better
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On a V32bis dial-up modem connection : 10's of milliseconds (from one
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session to the next)
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With a good reference clock the accuracy can reach one microsecond.
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chronyd can also operate as an RFC1305-compatible NTP server and peer.
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What will chrony run on?
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========================
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Chrony can be successfully built and run on
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1. Linux v1.2.13, v2.0.x, 2.1.x (partially), 2.2.x, 2.3.x, 2.4.x, 2.6.x.
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Real time clock support is limited to 2.0.32 onwards and to 2.2, 2.3,
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2.4 and 2.6 series only. i386, x86_64, PowerPC are known to be
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supported.
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2. Solaris 2.5/2.5.1/2.6/2.7/2.8 (various platforms)
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3. SunOS 4.1.4 (Sparc 2 and Sparc 20)
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4. BSD/386 v1.1 has been reported to work using the SunOS 4.1 driver.
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5. NetBSD.
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Any other system will require a porting exercise. You would need to
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start from one of the existing system-specific drivers and look into
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the quirks of certain system calls and the kernel on your target
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system. (This is described in the manual).
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How do I set it up?
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===================
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The file INSTALL gives instructions. On supported systems the
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compilation process should be automatic.
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You will need an ANSI C compiler -- gcc is recommended.
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The manual (in texinfo and text formats) describes how to set the
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software up for the less straightforward cases.
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What documentation is there?
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============================
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A manual is supplied in Texinfo format (chrony.texi) and
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ready-formatted plain text (chrony.txt) in the distribution.
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There is also information available on the chrony web pages, accessible
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through the URL
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http://chrony.tuxfamily.org/
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What can chrony not do?
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=======================
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Compared to the `reference' RFC1305 implementation xntpd, chronyd does
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not support broadcast modes.
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Where are new versions announced?
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=================================
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There is a low volume mailing list where new versions and other
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important news relating to chrony is announced. You can join this list
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by sending mail with the subject "subscribe" to
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chrony-announce-request@chrony.tuxfamily.org
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These messages will be copied to chrony-users (see below). New versions
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are announced also on Freshmeat (http://freshmeat.net/).
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How can I get support for chrony?
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and where can I discuss new features, possible bugs etc?
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========================================================
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There are 3 mailing lists relating to chrony. chrony-announce was
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mentioned above. chrony-users is a users' discussion list, e.g. for
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general questions and answers about using chrony. chrony-dev is a more
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technical list, e.g. for discussing how new features should be
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implemented, exchange of information between developers etc. To
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subscribe to either of these lists, send a message with the subject
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"subscribe" to
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chrony-users-request@chrony.tuxfamily.org
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or
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chrony-dev-request@chrony.tuxfamily.org
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as applicable.
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Author
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======
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Richard P. Curnow <rc@rc0.org.uk>
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Maintainers
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===========
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John Hasler <john@dhh.gt.org>
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Miroslav Lichvar <mlichvar@redhat.com>
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Acknowledgements
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================
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The following people have provided patches and other major contributions
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to the program :
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Benny Lyne Amorsen <benny@amorsen.dk>
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Patch to add minstratum option
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Andrew Bishop <amb@gedanken.demon.co.uk>
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Fixes for bugs in logging when in daemon mode
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Fixes for compiler warnings
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Robustness improvements for drift file
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Improve installation (directory checking etc)
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Entries in contrib directory
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Improvements to 'sources' and 'sourcestats' output from chronyc
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Improvements to documentation
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Investigation of required dosynctodr behaviour for various Solaris
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versions.
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Stephan I. Boettcher <stephan@nevis1.columbia.edu>
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Entries in contrib directory
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Erik Bryer <ebryer@spots.ab.ca>
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Entries in contrib directory
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Juliusz Chroboczek <jch@pps.jussieu.fr>
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Fix install rule in Makefile if chronyd file is in use.
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Paul Elliott <pelliott@io.com>
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DNSchrony (in contrib directory), a tool for handling NTP servers
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with variable IP addresses.
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Mike Fleetwood <mike@rockover.demon.co.uk>
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Fixes for compiler warnings
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Alexander Gretencord <arutha@gmx.de>
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Changes to installation directory system to make it easier for
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package builders.
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Walter Haidinger <walter.haidinger@gmx.at>
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Providing me with login access to a Linux installation where v1.12
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wouldn't compile, so I could develop the fixes for v1.13. Also, for
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providing the disc space so I can keep an independent backup of the
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sources.
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Juergen Hannken-Illjes <hannken@eis.cs.tu-bs.de>
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Port to NetBSD
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John Hasler <john@dhh.gt.org>
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Changes to support 64 bit machines (i.e. those where
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sizeof(unsigned long) > 4)
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Bug fix to initstepslew directive
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Fix to remove potential buffer overrun errors.
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Memory locking and real-time scheduler support
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Fix fault where chronyd enters an endless loop
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Liam Hatton <me@liamhatton.com>
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Advice on configuring for Linux on PPC
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Jachym Holecek <jakym@volny.cz>
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Patch to make Linux real time clock work with devfs
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Håkan Johansson <f96hajo@chalmers.se>
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Patch to avoid large values in sources and sourcestats output
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Jim Knoble <jmknoble@pobox.com>
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Fixes for compiler warnings
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Antti Jrvinen <costello@iki.fi>
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Advice on configuring for BSD/386
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Miroslav Lichvar <mlichvar@redhat.com>
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Reference clock support
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IPv6 support
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Linux capabilities support
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Leap second support
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Improved source selection
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Improved sample history trimming
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Improved polling interval adjustment
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Improved stability with temporary asymmetric delays
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Temperature compensation
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Many other bug fixes and improvements
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Victor Moroz <vim@prv.adlum.ru>
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Patch to support Linux with HZ!=100
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Kalle Olavi Niemitalo <tosi@stekt.oulu.fi>
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acquisitionport support
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Frank Otto <sandwichmacher@web.de>
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Handling arbitrary HZ values
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Andreas Piesk <apiesk@virbus.de>
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Patch to make chronyc use the readline library if available
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Timo Teras <timo.teras@iki.fi>
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Patch to reply correctly on multihomed hosts
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Wolfgang Weisselberg <weissel@netcologne.de>
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Entries in contrib directory
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Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
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Many robustness and security improvements
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Ulrich Windl <ulrich.windl@rz.uni-regensburg.de> for the
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Providing me with information about the Linux 2.2 kernel
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functionality compared to 2.0.
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Doug Woodward <dougw@whistler.com>
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Advice on configuring for Solaris 2.8 on x86
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Many other people have contributed bug reports and suggestions. I'm
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sorry I can't identify all of you individually.
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vim:tw=72
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