Playing with dates

[dUbbsNIX]

I have a date in the format YYMMDD, I wish to know such things as what day of the week is it, or what is it in Julian format, are you aware of any date conversion routines out there, or do I have to start from scratch ?

 

[markus38]

Have you tried man date perhaps?

 

[vgersh99]

something like this for Julinan<->Gregorian

#!/bin/ksh
#-----------------------------------------------------------------------------
# Date manipulation routines - convering to Julian and back
#
# Julian Day Number from calendar date
date2julian() #  day month year
{
  typeset year=$1;  typeset month=$2;  typeset day=$3
  tmpmonth=$((12 * year + month - 3))
  tmpyear=$((tmpmonth / 12))
  print $(( (734 * tmpmonth + 15) / 24 -  2 * tmpyear +     tmpyear/4 - tmpyear/100 + tmpyear/400 + day + 1721119 ))
}

# Calendar date from Julian Day Number
julian2date() # julianday
{
  #set -x
  typeset tmpday=$(($1 - 1721119))
  typeset centuries=$(( (4 * tmpday - 1) / 146097))
  tmpday=$((tmpday + centuries - centuries/4))
  typeset year=$(( (4 * tmpday - 1) / 1461))
  tmpday=$((tmpday - (1461 * year) / 4))
  typeset month=$(( (10 * tmpday - 5) / 306))
  day=$((tmpday - (306 * month + 5) / 10))
  month=$((month + 2))
  year=$((year + month/12))
  month=$((month % 12 + 1))
  printf "%s %02d %02d" $year $month $day
}

# Day of week, Monday=1...Sunday=7
dow() # year month day
{
  print $(( $(date2julian $1 $2 $3) % 7 + 1))
}

vlad
+----------------------------+
| #include<disclaimer.h> |
+----------------------------+

 

[dUbbsNIX]

Thanks for this vlad. I'll add some error checking to your script and probabley use it. As for doing a man on date(1), I don't really have any comment.

thanks again,

Dubbs.