#From: damatex@CAM.ORG (Mario Boudreault)
#Newsgroups: comp.unix.shell
#Subject: JULIAN DATE CONVERSION SUB
#Date: 4 Aug 1995 10:23:28 -0400
#Message-ID: <3vtah0$jb3@ocean.CAM.ORG>
#For those using shells and who want to convert dates to a julian number
#here is a shell script (wihtout validation) that can be used as a base
#program for your shell scripts.
#Special thanks to Ed Ferguson@ti.com who sent me the algorithm to compute
#that date.
#
# MODIFIED BY CHET RAMEY TO CONVERT TO bash v2 SYNTAX
#
# cnvdate - Conversion de dates en julienne et vice et versa...
#
# Par : Mario Boudreault Damatex Inc Montreal, Canada
# Date: 2 Aout 1995
# Rev.: 2 Aout 1995
#
# Usage:
# cvdate [-j] YYYMMDD pour convertir en nbre de jours
# cvdate -d {julian number} pour convertir en AAAAMMJJ
#
jul_date()
{
#
# Separe ANNEE, MOIS et JOUR...
#
YEAR=`echo $DATE | awk ' { print substr($0,1,4) } '`
MONTH=`echo $DATE | awk ' { print substr($0,5,2) } '`
DAY=`echo $DATE | awk ' { print substr($0,7,2) } '`
#
# Execute la formule magique...
#
A=$(( $DAY - 32075 + 1461 * ( $YEAR + 4800 - ( 14 - $MONTH ) / 12 ) \
/ 4 + 367 * ( $MONTH - 2 + ( 14 - $MONTH ) / 12 * 12 ) / 12 - \
3 * ( ( $YEAR + 4900 - ( 14 - $MONTH ) / 12 ) / 100 ) / 4 ))
echo $A
}
day_date()
{
TEMP1=$(( $DATE + 68569 ))
TEMP2=$(( 4 * $TEMP1 / 146097 ))
TEMP1=$(( $TEMP1 - ( 146097 * $TEMP2 + 3 ) / 4 ))
Y=$(( 4000 * ( $TEMP1 + 1 ) / 1461001 ))
TEMP1=$(( $TEMP1 - 1461 * $Y / 4 + 31 ))
M=$(( 80 * $TEMP1 / 2447 ))
D=$(( $TEMP1 - 2447 * $M / 80 ))
TEMP1=$(( $M / 11 ))
M=$(( $M + 2 - 12 * $TEMP1 ))
Y=$(( 100 * ( $TEMP2 - 49 ) + $Y + $TEMP1 ))
M=`echo $M | awk ' { M=$0 ; if ( length($0) == 1 ) M="0"$0 } END { print M } '`
D=`echo $D | awk ' { D=$0 ; if ( length($0) == 1 ) D="0"$0 } END { print D } '`
echo $Y$M$D
}
# main()
if [ $# -eq 1 ]; then
DATE=$1
jul_date
elif [ "$1" = '-j' ]; then
DATE=$2
jul_date
elif [ "$1" = '-d' ]; then
DATE=$2
day_date
fi
#
# Termine
#
exit 0