Shell Programming and Scripting

Hi All,
Thanks in Advance.

I want a function/script which returns the weekday of the given date.
the input to the function/script is the date with format MM/DD/YYYY, it should return the weekday as 1 for sunday, 2 for monday .......7 for saturday.

ex: if the function called like this date_func 12/15/2005
it should return 5 (thursday)


your help will be greatly appreciated


Regards,
Rinku

Look at datecalc

one more way,

not thoroughly tested

Code:

>cat weekday
# !/usr/bin/bash

weekday=$1

month=`echo ${weekday:0:2}`
day=`echo ${weekday:3:2}`
year=`echo ${weekday:6:4}`
weekday=1

for dayval in `cal $month $year | grep $day`
do
 if [ $day -ne $dayval ]
 then
   weekday=$(($weekday + 1))
 else
   break
 fi
done

echo "weekday is $weekday"

exit 0

hi,

just saw the datecalc...was checking the julian day option for the same.If i want to find todays julian day using "date" command the output is:

$date +%j
$350

but if i use datecalc for calculating todays julian day:

$datecalc -j 2005 12 16
$53720

just wondering what the output means here

would be great if someone can throw some light on the same

regards,
Bhups

http://en.wikipedia.org/wiki/Julian_day

First of all,

"The Julian day or Julian day number (JDN) is the number of days that have elapsed since 12 noon Greenwich Mean Time (UT or TT) on Monday, January 1, 4713 BC in the proleptic Julian calendar."

datecalc is using the modified julian day number:

"The Modified Julian Day (MJD), introduced by the Smithsonian Astrophysical Observatory in 1957 to record the orbit of Sputnik, is defined in terms of the Julian day as follows: MJD = JD - 2400000.5 The offset of 0.5 means that MJD started at midnight at the beginning of November 17, 1858, and that every Modified Julian Day begins and ends at midnight UT or TT."

The author of the date program you are using has confused day-of-year with julian day:

"The use of Julian date to refer to the day-of-year (ordinal date) is usually considered to be incorrect."

hi Perderabo,

thanks for the info ...i really use to think that julian day refer to (what you say) day-of-year...

so my next obvious question is how to get day-of-year from datecalc??

in my scripts i always come across this prob of converting julain date (CCYY DDD) to the MM DD YY format, so it would be a great help if i could use datecalc for the same purpose

thanks in advance...

regards,
Bhups.

Should Jan 1 be a zero or a one? Both schemes are in use.

Compute the mjd of January 1 for the year. (Should Jan 1 be 1? If so subtract one.) Subtract the result from the mjd of the date to get day-of-year.