411 lines
12 KiB
Plaintext
411 lines
12 KiB
Plaintext
\input texinfo @c -*-texinfo-*-
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@c %**start of header
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@setfilename vsntp.info
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@include version.texi
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@settitle vsntp v@value{VERSION}
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@syncodeindex vr cp
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@syncodeindex pg cp
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@c %**end of header
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@copying
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This manual is for vsntp
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(version @value{VERSION}, @value{UPDATED}),
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a SNTP daemon for Virtual @acronym{PC}@.
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Copyright @copyright{} 2003-2007 imacat@.
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@quotation
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the @acronym{GNU} Free Documentation License, Version 1.2
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts@.
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A copy of the license is included in the section entitled ``@acronym{GNU}
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Free Documentation License''@.
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@end quotation
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@end copying
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@titlepage
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@title vsntp v@value{VERSION}
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@c The following two commands start the copyright page.
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@page
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@vskip 0pt plus 1filll
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@insertcopying
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Published by imacat@*
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@email{imacat@@mail.imacat.idv.tw}@*
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@uref{http://www.imacat.idv.tw/}@*
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@end titlepage
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@c Output the table of contents at the beginning.
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@contents
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@ifnottex
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@node Top
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@top Short Sample
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@insertcopying
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@end ifnottex
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@menu
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* Introduction::
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* Download the Newest Version: Download.
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* Compilation and Installation: Install.
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* Running and Stopping: Run.
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* Command Line Options: Options.
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* Supports and Bugs Report: Support.
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* References::
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* Copyright::
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* Index::
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@end menu
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@node Introduction
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@chapter Introduction
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@pindex Virtual PC
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@pindex Connectix Virtual PC
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@cindex RFC 1769 SNTP
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@cindex UDP
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@dfn{vsntp} is an @acronym{SNTP} client daemon for machines without a
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sane system time@. The word ``@dfn{vsntp}'' stands for
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``@dfn{@acronym{SNTP} for Virtual PC}''@. It was originally designed
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for my @acronym{GNU}/Linux server running on Connectix Virtual @acronym{PC}@.
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It runs according to @acronym{RFC} 1769 @acronym{SNTP}, connecting
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the @acronym{NTP} server on @acronym{UDP} port 123@. It was originally
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written for @acronym{GNU}/Linux@.
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Without Virtual @acronym{PC} Additions, the system time on Virtual @acronym{PC} is
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completely insane@. It's @acronym{RTC} (Real Time Clock, or
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@acronym{CMOS} time, or hardware clock) is software emulated, which
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does not seems to be running@. The @acronym{GNU}/Linux kernel hardly
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maintains a system time itself@. With smooth run it goes 4 seconds
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ahead per minute, which is nearly 1.5 hours per day@. That is
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insane@. You can even tell it with your eyes@.
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@pindex David L. Mills
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@pindex ntp
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@findex adjtimex()
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@uref{http://www.ntp.org/,David L. Mills' @command{ntp}} does not
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work here@. It uses a method that learns the clock frequency drift
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first, and adjust the kerenl clock with @code{adjtimex()} so that
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time adjustment goes smoothly, from the point of view of system and
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applications@. This assumes an existing fix-speed system clock@.
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But this is not the case of Virtual @acronym{PC}@. The system clock
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on Virtual @acronym{PC} is software emulated@. It can be faster or
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slower now and then, depending on the load of the hosting machine@.
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There is no fixed clock speed@. The frequency drift does not exist,
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then@. It dooms to fail to measure it@.
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@pindex sntp
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There is an @command{sntp} client that comes with David L. Mills'
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@command{ntp} package@. It is suggested to be run from
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@command{crontab}@. But @command{crontab} runs by minutes, and
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Virtual @acronym{PC} goes 4 seconds ahead per minute@. Rolling back
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4 seconds every minute is insane for most applications@. It also
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increases system load heavily to run one instance per minute@.
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@findex settimeofday()
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@command{vsntp} is a workaround on this@. It runs as a daemon to
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eliminates the additional system load on every synchronization@. It
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uses @code{settimeofday()} to synchronize the time@. It synchronizes
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the time with an arbitrary interval, so that time can be accurate
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within a second@.
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There are some defects@. Synchronizing the time too often introduces
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heavy network load@. It introduces heavy load on the target
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@acronym{NTP} server, too@. You should have a working
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@acronym{NTP} server nearby that is owned by you@. Also, since
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@code{settimeofday()} is called so often, high-accurate time
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operations like timer, @acronym{etc.}, may not run correctly@.
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@findex sleep()
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@findex alarm()
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@command{vsntp} uses @code{sleep()} as the synchronization scheduler.
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Reports show that on some systems @code{sleep()} may not function
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normally@. If you find @command{vsntp} stops synchronization after
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running for some time, that the @code{sleep()} is not functioning
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normally on your system, you may want to switch to the @code{alarm()}
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scheduler with the @option{-a} switch@.
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If you ever encounter any problem, you may check your syslog@.
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@command{vsntp} logs detailed debugging information to syslog in log
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level @code{LOG_DEBUG} with facility @code{LOG_DAEMON}@. You may turn
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it on in your @file{/etc/syslog.conf} with the following line:
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@example
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daemon.debug /var/log/debug
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@end example
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and check the @file{/var/log/debug} file for the debugging message@.
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Remember to remove this afterwards, for the amount of the debugging
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messages may be huge and may use up your harddisk in a very short
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time@. To the least it may slow down your system for frequent
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harddisk @acronym{I/O}@.
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@command{vsntp} was originally written for @acronym{GNU}/Linux@. It
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uses @acronym{POSIX} compatible system calls@. It should work on
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any @acronym{POSIX} compatible system@. But I have yet only tested
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it on @uref{http://www.cygwin.com/, Cygwin}@. Cygwin is known to
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work. I don't have others to test and run on. Please
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let me know (and submit the patch if needed) if you can port it to
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other systems@. I know it does not work on MSWin32, for the way it
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handles the @acronym{PID} file path@.
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Please tell me if you have successfully running @command{vsntp} on
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other virtual machines, like @uref{http://www.vmware.com/, VMWare}@.
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Generally, please tell me if you are using @command{vsntp}@. I
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would like to know that I am really doing some good for the world,
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*^_^* but not having fun myself@. :p
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@node Download
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@chapter Download the Newest Version
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@cindex website
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@cindex official website
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@cindex download
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@cindex SourceForge
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@cindex Tavern IMACAT's
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@command{vsntp}'s official website is at@dots{}
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@itemize
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@item
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@uref{https://sourceforge.net/,SourceForge}'s home site:
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@uref{http://vsntp.sourceforge.net/}
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@item
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@uref{https://sourceforge.net/,SourceForge}'s project page:
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@uref{https://sourceforge.net/projects/vsntp/}
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@item
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@uref{http://www.imacat.idv.tw/,Tavern IMACAT's} page:
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@uref{http://www.imacat.idv.tw/tech/vsntp.html}
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@end itemize
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You can always download the newest version of @command{vsntp}
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from@dots{}
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@itemize
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@item
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SourceForge:
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@uref{https://sourceforge.net/project/showfiles.php?group_id=99098}
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@item
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Tavern IMACAT's @acronym{FTP}:
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@uref{ftp://ftp.imacat.idv.tw/pub/vsntp/}
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@end itemize
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imacat's @acronym{PGP} public key is at@dots{}
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@itemize
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@item
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SourceForge:
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@uref{http://vsntp.sourceforge.net/pgpkey.asc}
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@item
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Tavern IMACAT's:
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@uref{http://www.imacat.idv.tw/me/pgpkey.asc}
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@end itemize
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@node Install
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@chapter Compilation and Installation
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@command{vsntp} uses standard @acronym{GNU} @command{autoconf} to
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compile and install:
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@enumerate
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@item
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Download, unzip and untar the @command{vsntp} package:
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@example
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% tar xzf vsntp-@value{VERSION}.tar.gz
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@end example
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@item
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Go into its directory:
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@example
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% cd vsntp-@value{VERSION}
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@end example
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@pindex configure
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@item
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Configure with @command{./configure}:
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@example
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% ./configure
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@end example
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@item
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Compile with @command{make}:
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@example
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% make
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@end example
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The resulted executable will be named @file{vsntp}@.
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@item
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You need to be @code{root} in order to install @command{vsntp}:
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@example
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% su
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Password:
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#
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@end example
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@item
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You can simply copy @command{vsntp} to the appropriate directory:
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@example
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# cp vsntp /usr/local/sbin
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@end example
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Or, you can run automatic install:
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@example
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# make install
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@end example
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You can reduce the size of the installed executable by stripping off
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debug symbols inside:
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@example
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# make install-strip
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@end example
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By default @command{vsntp} will be installed in
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@file{/usr/local/sbin}@.
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@end enumerate
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@node Run
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@chapter Running and Stopping
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You need to be @code{root} to run @command{vsntp}@. @command{vsntp}
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uses @code{settimeofday()} to set the system time@.
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@code{settimeofday()} requires @code{root} privilege@.
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To start @command{vsntp}, just specify your @acronym{NTP} server:
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@example
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# vsntp my.ntp.server.com
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@end example
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@command{vsntp} writes its @acronym{PID} in
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@file{/var/run/vsntp.pid}@. To stop @command{vsntp}, @command{kill}
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it by its @acronym{PID}:
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@example
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# kill `cat /var/run/vsntp.pid`
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@end example
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The @acronym{PID} file location can be changed with the @option{-p}
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switch.
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@node Options
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@chapter Command Line Options
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@defopt{-i,--interval} @var{n}
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Set the synchronization interval to @var{n} seconds@. Default is
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900@dmn{sec} (15@dmn{min})@.
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@end defopt
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@defopt{-p,--pidfile} @var{file}
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The @acronym{PID} file location@. Default to @file{/var/run/vsntp.pid}@.
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@end defopt
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@defopt{-s,--sleep}
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Use @code{sleep()} to schedule synchronization@. (default)
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@end defopt
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@defopt{-a,--alarm}
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Use @code{alarm()} to schedule synchronization@.
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@end defopt
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@defopt{-h,--help}
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Display the help message@.
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@end defopt
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@defopt{-v,--version}
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Display version information@.
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@end defopt
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@node Support
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@chapter Supports and Bugs Report
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@cindex SourceForge
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@cindex Tavern IMACAT's
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@command{vsntp} is hosted on
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@uref{https://sourceforge.net/,SourceForge} and
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@uref{http://www.imacat.idv.tw/,Tavern IMACAT's}@. For the latest
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infomation, see:
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@itemize
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@item
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@uref{http://vsntp.sourceforge.net/}
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@item
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@uref{https://sourceforge.net/projects/vsntp/}
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@item
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@uref{http://www.imacat.idv.tw/tech/vsntp.html}
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@end itemize
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@cindex mailing list
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@cindex Mailman
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@command{vsntp} has a mailing list hosted at
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@uref{https://sourceforge.net/,SourceForge}:
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@email{vsntp-users@@lists.sourceforge.net}@. Please submit your
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questions, suggestions or bug reports there@. It is a
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@uref{http://www.list.org/,Mailman} mailing list@. For more
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information, see:
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@uref{https://lists.sourceforge.net/lists/listinfo/vsntp-users}@.
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Alternatively, you can send a mail to:
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@email{vsntp-users-request@@lists.sourceforge.net}
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with the subject @code{help} for a list of available e-mail
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commands@.
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@node References
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@unnumbered References
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@findex settimeofday()
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@findex adjtimex()
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@pindex ntp
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@cindex RFC 1769 SNTP
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@cindex RFC 1305 NTP
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@itemize
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@item
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@inforef{High-Resolution Calendar, ,libc}, for settimeofday() and adjtimex().
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@inforef{Setting an Alarm, ,libc}, for alarm().
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@inforef{Sleeping, ,libc}, for sleep().
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@item
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@uref{http://www.ntp.org/,ntp}
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@item
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@uref{http://www.faqs.org/rfcs/rfc1769.html,@acronym{RFC} 1769 @acronym{SNTP}}.
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@item
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@uref{http://www.faqs.org/rfcs/rfc1305.html,@acronym{RFC} 1305 @acronym{NTP}}.
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@end itemize
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@node Copyright
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@unnumbered Copyright
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@quotation
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Copyright @copyright{} 2003-2007 imacat@.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the @cite{@acronym{GNU} General Public License}
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as published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version@.
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This program is distributed in the hope that it will be useful,
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but @emph{WITHOUT ANY WARRANTY}; without even the implied warranty of
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@emph{MERCHANTABILITY} or @emph{FITNESS FOR A PARTICULAR PURPOSE}@.
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See the @cite{@acronym{GNU} General Public License} for more details@.
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You should have received a copy of the @cite{@acronym{GNU} General
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Public License} along with this program@. If not, see
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<@uref{http://www.gnu.org/licenses/}>@.
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@end quotation
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@node Index
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@unnumbered Index
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@printindex cp
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@bye
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@bye
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