examples/functions/jdate.bash

   1 #From: damatex@CAM.ORG (Mario Boudreault)
   2 #Newsgroups: comp.unix.shell
   3 #Subject: JULIAN DATE CONVERSION SUB
   4 #Date: 4 Aug 1995 10:23:28 -0400
   5 #Message-ID: <3vtah0$jb3@ocean.CAM.ORG>
   6
   7 #For those using shells and who want to convert dates to a julian number
   8 #here is a shell script (wihtout validation) that can be used as a base
   9 #program for your shell scripts.
  10
  11 #Special thanks to Ed Ferguson@ti.com who sent me the algorithm to compute
  12 #that date.
  13
  14 #
  15 # MODIFIED BY CHET RAMEY TO CONVERT TO bash v2 SYNTAX
  16 #
  17
  18 # cnvdate - Conversion de dates en julienne et vice et versa...
  19 #
  20 # Par : Mario Boudreault       Damatex Inc   Montreal, Canada
  21 # Date: 2 Aout 1995
  22 # Rev.:  2 Aout 1995
  23 #
  24 # Usage:
  25 #          cvdate [-j] YYYMMDD          pour convertir en nbre de jours
  26 #          cvdate -d {julian number}    pour convertir en AAAAMMJJ
  27 #
  28
  29 jul_date()
  30 {
  31         #
  32         # Separe ANNEE, MOIS et JOUR...
  33         #
  34         YEAR=`echo $DATE | awk ' { print substr($0,1,4) } '`
  35         MONTH=`echo $DATE | awk ' { print substr($0,5,2) } '`
  36         DAY=`echo $DATE | awk ' { print substr($0,7,2) } '`
  37         #
  38         # Execute la formule magique...
  39         #
  40         A=$(( $DAY - 32075 + 1461 * ( $YEAR + 4800 - ( 14 - $MONTH ) / 12 ) \
  41                 / 4 + 367 * ( $MONTH - 2 + ( 14 - $MONTH ) / 12 * 12 ) / 12 - \
  42                 3 * ( ( $YEAR + 4900 - ( 14 - $MONTH ) / 12 ) / 100 ) / 4 ))
  43         echo $A
  44 }
  45
  46 day_date()
  47 {
  48         TEMP1=$(( $DATE + 68569 ))
  49         TEMP2=$(( 4 * $TEMP1 / 146097 ))
  50         TEMP1=$(( $TEMP1 - ( 146097 * $TEMP2 + 3 ) / 4 ))
  51         Y=$(( 4000 * ( $TEMP1 + 1 ) / 1461001 ))
  52         TEMP1=$(( $TEMP1 - 1461 * $Y / 4 + 31 ))
  53         M=$(( 80 * $TEMP1 / 2447 ))
  54         D=$(( $TEMP1 - 2447 * $M / 80 ))
  55         TEMP1=$(( $M / 11 ))
  56         M=$(( $M + 2 - 12 * $TEMP1 ))
  57         Y=$(( 100 * ( $TEMP2 - 49 ) + $Y + $TEMP1 ))
  58         M=`echo $M | awk ' { M=$0 ; if ( length($0) == 1 ) M="0"$0 } END { print M } '`
  59         D=`echo $D | awk ' { D=$0 ; if ( length($0) == 1 ) D="0"$0 } END { print D } '`
  60         echo $Y$M$D
  61 }
  62
  63 # main()
  64
  65 if [ $# -eq 1 ]; then
  66         DATE=$1
  67         jul_date
  68 elif [ "$1" = '-j' ]; then
  69         DATE=$2
  70         jul_date
  71 elif [ "$1" = '-d' ]; then
  72         DATE=$2
  73         day_date
  74 fi
  75 #
  76 # Termine
  77 #
  78 exit 0