Imported from ../bash-2.02.tar.gz.

examples/functions/jdate.bash

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+#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