mdw@git.distorted.org.uk Git - rsync-backup/blob - lib.sh.in

   1 ### -*-bash-*-
   2 ###
   3 ### Common utilities for rsync-backup scripts
   4 ###
   5 ### (c) 2014 Mark Wooding
   6 ###
   7
   8 ###----- Licensing notice ---------------------------------------------------
   9 ###
  10 ### This file is part of the `rsync-backup' program.
  11 ###
  12 ### rsync-backup is free software; you can redistribute it and/or modify
  13 ### it under the terms of the GNU General Public License as published by
  14 ### the Free Software Foundation; either version 2 of the License, or
  15 ### (at your option) any later version.
  16 ###
  17 ### rsync-backup is distributed in the hope that it will be useful,
  18 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ### GNU General Public License for more details.
  21 ###
  22 ### You should have received a copy of the GNU General Public License
  23 ### along with rsync-backup; if not, write to the Free Software Foundation,
  24 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25
  26 ###--------------------------------------------------------------------------
  27 ### Configuration.
  28
  29 VERSION=@VERSION@
  30 pkgdatadir=@pkgdatadir@
  31 mntbkpdir=@mntbkpdir@
  32 logdir=@logdir@
  33 fshashdir=@fshashdir@
  34 conf=@sysconfdir@/rsync-backup.conf
  35
  36 INDEXDB=@pkglocalstatedir@/index.db
  37
  38 SNAPDIR=$mntbkpdir/snap
  39 STOREDIR=$mntbkpdir/store
  40 METADIR=$mntbkpdir/meta
  41
  42 config () {
  43   echo
  44   cat <<EOF
  45 conf = $conf
  46 mntbkpdir = $mntbkpdir
  47 fshashdir = $fshashdir
  48 logdir = $logdir
  49 EOF
  50 }
  51
  52 ###--------------------------------------------------------------------------
  53 ### Date hacking.
  54
  55 parsedate () {
  56   date=$1
  57   ## Parse an ISO8601 DATE, and set YEAR, MONTH, DAY appropriately (and
  58   ## without leading zeros).
  59
  60   ## Extract the components of the date and trim leading zeros (which will
  61   ## cause things to be interpreted as octal and fail).
  62   year=${date%%-*} rest=${date#*-}; month=${rest%%-*} day=${rest#*-}
  63   year=${year#0} month=${month#0} day=${day#0}
  64 }
  65
  66 julian () {
  67   date=$1
  68   ## Convert an ISO8601 DATE to a Julian Day Number.
  69
  70   parsedate $date
  71
  72   ## The actual calculation: convert a (proleptic) Gregorian calendar date
  73   ## into a Julian day number.  This is taken from Wikipedia's page
  74   ## http://en.wikipedia.org/wiki/Julian_day#Calculation but the commentary
  75   ## is mine.  The epoch is 4713BC-01-01 (proleptic) Julian, or 4714BC-11-24
  76   ## proleptic Gregorian.
  77
  78   ## If the MONTH is January or February then set a = 1, otherwise set a = 0.
  79   a=$(( (14 - $month)/12 ))
  80
  81   ## Compute a year offset relative to 4799BC-03-01.  This puts the leap day
  82   ## as the very last day in a year, which is very convenient.  The offset
  83   ## here is sufficient to make all y values positive (within the range of
  84   ## the JDN calendar), and is a multiple of 400, which is the Gregorian
  85   ## cycle length.
  86   y=$(( $year + 4800 - $a ))
  87
  88   ## Compute the offset month number in that year.  These months count from
  89   ## zero, not one.
  90   m=$(( $month + 12*$a - 3 ))
  91
  92   ## Now for the main event.  The (153 m + 2)/5 term is a surprising but
  93   ## correct trick for obtaining the number of days in the first m months of
  94   ## the (shifted) year).  The magic offset 32045 is what you get when you
  95   ## plug the proper JDN epoch (year = -4713, month = 11, day = 24) into the
  96   ## above machinery.
  97   jdn=$(( $day + (153*$m + 2)/5 + 365*$y + $y/4 - $y/100 + $y/400 - 32045 ))
  98
  99   echo $jdn
 100 }
 101
 102 ###----- That's all, folks --------------------------------------------------