
                         p]wPǽTq
                                       
@: Ron Bean, [1]rbean@execpc.com
Ķ: Da-Wei Chiang, [2]dawei@sinica.edu.tw

   v, December 1996 ½Ķ: 2-16 July 1998
     _________________________________________________________________
   
   p]wPǽTq.
     _________________________________________________________________
   
1. 

2. ϥ``clock''{

     * 2.1 ˬdA@~t
     * 2.2 qtv
     * 2.3 
       
3. xntpd ²
     _________________________________________________________________
   
1. 

   ӤHq(ƦܩQu@)DOWҨϥΪ real-time-clock 
   TOҬҪƱ. M Linux @~tδѤF@²檺kӮեoӤ
   ǽTq, ϱoqNOʿ~ծɷ]iHF *۷*
   ǽTaB. OGjhƤH٤DoӤk, ]pU:
   
    1. b@ ``p]w linux @~t'' 󤤨åzγoӤk, ӥBb
       w˧@~tήɫ۰ʦa]w (OzפWäOi઺, pGA
       @xƾھ).
    2. YAϥ``man clock''Ӭdݳ]w, Ai|oDw
       clock(3) e. (յۨϥ``man 8 clock'').
    3. GjhƤHäbN{bTɨOh.
    4. ǤּƦbNH|ĥ louie.udel.edu ҴѪ xntpd {HK
       P~ծɷ, ҦpծɦAεLuqH, oPB.
       
   pGU糧zC]wk۷ת, ڱjPĳU
   Ǯɶs [3]http://www.eecis.udel.edu/~ntp/ , oӺ
   UAҷP쪺e,Ҧp xntpd TH NIST P USNO 
   xWs. (ڦb᭱] xntpd @Fǳ\².)
   
   `N
          pGAbP@xW]hӧ@~t, Aӥu䤤@Өӭs]w
          CMOS , pפ|ۤvTӾɭPV. ϧA`bP@x
          W] Linux M Windows Gا@~t, ӷAnM@Ǧ@ɪ
          ɵ{KɥiH Windows @~tΪ (ѦҫeһW
          s).
          
2. ϥ``clock''{

   ҦAnDeb clock(8) , ӥNaU짹ӳ]
   w{.
   
   `N
          n``clock''άO䥦|vTtήɶM CMOS {, A
          ֦ root v.
          
2.1 ˬdA@~t

   ˬdA@~tΪ}ɤO_``clock -a'' ``clock -ua''R
   O. oөROib /etc/rc.local , /etc/rc.d/rc.sysinit , Ψ䥦
   a, onݧAw˪O@M Linux @~t.
   
   pG쪺ROO ``clock -s''  ``clock -us'' , бN ``s'' 令
   ``a'' , ˬdݬݬO_ /etc/adjtime oɮ, ɮתeu@
   ݰ_ӹOo:
   
0.000000 842214901 0.000000

   oǼƦŗǬOե]l (CѰt), W@եɶ ( Jan
   1, 1970 }l_⪺), W@եҦ. pGA䤣oɮ,
   ХH root ͦɮ, 䤺eu@ݰ_ӹOo (Os):
   
0.0 0 0.0

   MzL shell ʰ ``clock -a''  ``clock -ua'' HKsĤGӼ
   r (pGAQ]wհڮɶӤOaɶ Aoϥ ``u''oӰ
   ).
   
2.2 qtv

   AoD{b쩳OXI :-). AaɶiOǽT. ڳ
   wkOqܨ WWV  (303)499-7111 qܳɥx (oOӥIOq).
   pGAPծɦAsWu, A]iHϥ xntpd {ҴѪ
   ntpdate {Ӯծ (ϥ -b ﶵHקKtΧ˶ CMOS ). Ϊ̨ϥ
   ``date -s hh:mm:ss'' Hʤ覡]wtή, ר@ؤk᳣̫oϥ
   ``clock -w'' NtήɶgJ CMOS . AOo̫@]w
   , ҥHAoNӤgUөb|򥢪a. pGAϥΪO ntpdate {
   ,  ``date +%s'' MgU۱q Jan 1,1970 _ӵ{檺.
   
   MᵥݴXѩδXӬPᤧA^Ӭݬݮ쩳tFh֮ɶ. pGAH
   ʪ覡]w, ĳܤֱoݤGӬP, AӭptvNi
   oͪ .1 sec/day G. XӤ뤧᰾tvӷ|ͪ .01 sec/day (
   ǤHźӧǽT, OڭӤHOdA). pGAϥ ntpdate {
   ]wAiणݤӤ[ɶ, MӤרϥΨؤ覡᳣oǷL
   u@.
   
   AiHϥ cron b@wɶP ``clock -a'' HKtήɶP
   (եL) CMOSɶ@P. bAC}ɭԳ|q}ɨ
   oөRO, Mӥun``WoӰʧ@NiHFAǽTɶ
   .
   
   `NpGtήɶץ@WL@άOɶ^ץ, ǨtΪ clock {
   i|Lk. pGAo譱D, hiHϥ xntpd  ntpdate {
    ӳvBaץɶ.
   
2.3 

  ]wɶ
  
   ñJtΨæ root. qܦ (303)499-7111 (y), Ӳťɪe.
   MϥLXUXӦr:
   
date -s hh:mm:ss

   @ͪ@n׫U enter . (pGbBϥ ``ntpdate'' {, hA
   iHٲqܪʧ@) oӨBJb]w ``tήɶ''. ۰:
   
clock -w

   oӨBJNtήɶg^ CMOS G̮ɶ@P. ۰:
   
date +%j

   (pGbeϥ ``ntpdate'' {Ao ``date +%s'') N檺GO
   U.
   
  s]wɶPˬdtv
  
   XAWgUӤ. ñJtΨæ root. M:
   
clock -a

   oӨBJN CMOS ɶgJtήG̮ɶ@P. qܦ (303)499-7111
   (y), Ӳťɪe. ۨϥLXUXӦr:
   
date

   @ͪ@n׫U enter , OAݪɭ, gUɪe, 
   B٤nWq. oӰʧ@OADثeuɶOXI, Ӧɬ۹A
   WɶOXI. {bϥLXUXӦr:
   
date -s hh:mm:00

   䤤wҳ]wƦrNOثeɤe *᪺* U@, @
   @n׫U enter  ({biHWqܤF).  hh hϥξa
   ɰwƦrYi. oӨBJb]w ``tήɶ''. M:
   
clock -w

   Ns (եL) tήɶg^ CMOS . M:
   
date +%j

   (άO ``date +%s'' )
   
   A{bWTӼƦr (GӮեΤ@ӥTɶ) OAiH}lpⰾ
   tvF.
   
  pե]l
  
   AbY@ ``date'' {, AaɶOC٬O֩O? pG
   O֤F, ANh@ǬƥHŦXTɶ, ҥHAӼgU@ӭt
   tƭ. pGOCF,AN[W@ǬƥHŦXTɶ, ҥHAӼgU
   @ӥtƭ.
   
   {bNGӮե۴. pGeAϥΪO ``date +%j'', hƭȩҥNN
   q@~ĴX (1-365,  1-366 pGO|~). pG۱qAW@]w
   {bgL1 1 AٶnNĤGӮե[ 365 ( 366) pGeA
   ΪO ``date +%s'' hƭȪ쬰, ANH 86400 HKo
   .
   
   pGAɮ /etc/adjtime wgե]l, ANewեL
   Ҽ{i, pGAեL, oӮե]ltNPAq찾tƭȬ
   ; pGAեhG̥tۦP. Nªե]lH, M[Ws
   ot (-- pGG̥tۦP, ANo@Ӹjtƭ,
   pGG̥tۤ, ANo@Ӹptƭ).
   
   ۱No`tưHƥHKosե]l, MNɮ
   /etc/adjtime ªե]lNs. ̫gUsե (HƩΤ
   Ƭ) HKUϥ.
   
   o̬Oڪ /etc/adjtime ɮפe:
   
-9.600000 845082716 -0.250655

   (`NC 9.6 h@ӤN 5 t!)
   
3. xntpd ²

   AtιڤWGӮ-- @ӬOt~ϥιqqOpɥ\
    ``real time clock'' (]NOҿת ``CMOS '', ``w'', 
   ``RTC'') ӥt@ӬO ``kernel clock'' (ɺ٬ ``n''  ``tή
   '') tήʬOHpɾ_HǨæb}ɱqCMOS B
   Jl. oGӮPɶtv, ҥHGӮWɶ|va
   Ͱt, ӥB]|P ``u''ɶͰt.
   
   b xntpd 󤤩ҭzΪ ``the clock'' NO ``kernel clock''. A
   xntpd  timed { (άOLϥΨ adjtimex tΩIs{) linux @
   ~tη|wtή CMOS ǽT, ӥB|b}Cj 11 s]
   w@ CMOS ɶ (@쭫}). oN ``clock'' {ADW
   @s]w CMOS Tɶ, ҥHAiHϥɮ /etc/adjtime 
   ե]l. AiHb}ɤWϥ ntpdate { HKb즸 xntpd
   {ePծɦA. pGAb}ɭԤ@LksWǽTծɷ,
   oi|A{@ǧx-- ڤW xntpd OQ]pӦbرpU
   Ϊ.
   
   Xntpd ]tF\hLuqXʵ{, åB]iHQ]wb@wP
   qܦ NIST qܼqծɪA (A]wnqܼP̦n
   p@Uqܱb檺O). bPLծɷhp@qɶoӤ覡]
   ണѨtή@Ӯե]l.
   
   jLuqjnO $3-4K, LAiHĥθKy ``gadget
   box''  (ڤWO@ 300 baud ƾھ) LQbAqP@xui
   Luq WDզ Canada  CHU ծɵLuqx (Ѩ}
   [4]ftp://ftp.udel.edu/pub/ntp/gadget.tar.Z). Heathkit WWV  (``
   ̷ǽT'') MR (O@ծM), jnO $4-500. 
   eGPS T̤M]tծɪT, ӥB GPS iHWq
   C. b̪񪺥ӳoi|C쪺ѨM.
   
   zפW, @HiHۤvg{Өϥ NIST qܼqծɪAȥHK۰
   p CMOS Ptήtv. MڤDO_W{F
   oӥت, Oj{XӥiHɥΦ xntpd {.

References

   1. mailto:rbean@execpc.com
   2. mailto:dawei@sinica.edu.tw
   3. http://www.eecis.udel.edu/~ntp/
   4. ftp://ftp.udel.edu/pub/ntp/gadget.tar.Z
