Convert epoch time to Julian date

Shell Programming and Scripting
1

Need assistance in converting an epoch time to Julian date

To get epoch

perl -e 'use Time::Local; print timelocal(1,5,2,12,10,2008), "\n"'
2

Are the numbers in the timelocal function call from a Gregorian date?

Does that mean to want to take a Gregorian date to an Epoch, and now you want to convert it a Julian date?

(it seems like an unusual request, so I just wanted to make sure :))

3

Yes from Gregarian calender to Julian date

---------- Post updated at 04:39 PM ---------- Previous update was at 01:52 PM ----------

Found a way to get the julian date

use POSIX qw(strftime);
my $time = timegm($sec,$min,$hour,$day,$mon,$year);
print strftime "%j", gmtime($time);
1 Like
4

You may try

#!/bin/bash

# Usage : Julian STANDARD DAY MON YEAR HOUR MIN SEC
function Julian(){

                   std=$1    
                   Day=$2 ; Mon=$3 ; Year=$4
                   Hour=$5; Min=$6 ; Sec=$7

case "$std" in
    CNES )
                 # Cnes Julian days start at January 1st, 1950    
                 start="Jan 1 1950 12:00:00 AM";;
    NASA ) 
                 # Nasa Julian days are number of days since January 1st, 1958 
                 start="Jan 1 1958 12:00:00 AM";;
        *) 
                 echo "Invalid option" && exit;;
esac

               # Julian Day
                 jd=$(( ( $(date -d "$Year$Mon$Day" +%s) - $(date -d "$start" +%s) ) /(24 * 60 * 60 ) ))
                 ttime=$(echo $Hour $Min $Sec | awk '{print $2/24 +$3/(60*24)+ $4/(60*60*24)}')

               # Realtime Julian Day
                 rjul=$(echo $jd $ttime | awk '{printf "%5.3f\n", $1+$2}')

                  }

printf "\nCalendar Date  : 31-12-2013 10:10:10\n\n"

# CNES Standard
Julian CNES 31 12 2013 10 10 10
printf "CNES Standard\n\tJulian Day : $jd\n\tRealtime Julian Day : $rjul\n"

# NASA Standard
Julian NASA 31 12 2013 10 10 10
printf "NASA Standard\n\tJulian Day : $jd\n\tRealtime Julian Day : $rjul\n\n"

Resulting

$ ./Julian

Calendar Date  : 31-12-2013 10:10:10

CNES Standard
    Julian Day : 23375
    Realtime Julian Day : 23375.424
NASA Standard
    Julian Day : 20453
    Realtime Julian Day : 20453.424

following link may be useful to you
http://www.aviso.oceanobs.com/en/data/tools/calendar-days-or-julian-days.html

1 Like