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
29jul_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 $A
44}
45
46day_date()
47{
48	TEMP1=$(( $DATE + 68569 ))
49	TEMP2=$(( 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
65if [ $# -eq 1 ]; then
66	DATE=$1
67	jul_date
68elif [ "$1" = '-j' ]; then
69	DATE=$2
70	jul_date
71elif [ "$1" = '-d' ]; then
72	DATE=$2
73	day_date
74fi
75#
76# Termine
77#
78exit 0
79