Is there a way (in the Korn Shell) to accurately increment a date ?



Say for example that I awk out the following "start_date" and "end_date" (in the format below) from a file:

start_date = 10/25/2004

end_date = 11/12/2004

How do I increment from the start_date to the end_date ?
(also note the change in months for the dates it is also possible that the years could be different)

I wuz given an example like this though :

(The above seem to work but I don't really understand it)

For my purposes I could very well work with this "solution"....except for the little problem that the dates that I would be feeding the script would look like :


10/26/2004 NOT Tue Oct 26 20:53:08 EST 2004


Is there a way to convert 10/26/2004 TO Tue Oct 26 20:53:08 EST 2004

Hi,
may be this can help.
http://www.dbforums.com/t1004206.html

Try...
...and you aren't subtracting 24 hours from the date, you are setting theTimeZone to be "EST-24" which is interpreted as 24 hours after EST.

btw This isn't a particularly portable, so don't be surprised if it doesn;t work in every shell you use!

################################################## ###################
# Example for your application
# start_date = 10/25/2004
# end_date = 11/12/2004
################################################## ###################

######## example to use idate.sc ####################################
######## Remember it is the german Format // Day / Month / Year // ##

start_date="25.10.2004"
end___date="12.11.2004"

echo "Start with "$start_date" and end with "$end___date
echo "--------------------------------------------------"

INF_start_date=`idate.sc $start_date`
INF_end___date=`idate.sc $end___date`
days_between_s_e=`expr $INF_end___date - $INF_start_date`

echo "INFORMIX Start_Date "$INF_start_date
echo "INFORMIX End_Date "$INF_end___date
echo "Days between Start and End "$days_between_s_e

echo "------- and now the way back ---------------------"
echo "--------------------------------------------------"

x=`expr $INF_end___date - 18`
start_date=`idate.sc $x`
y=`expr $INF_start_date + 18`
end_date=`idate.sc $y`

echo "Start_Date "$start_date
echo "End_Date "$end_date

##### And this will be the output ###################
##### for this example ###################
#
#Start with 25.10.2004 and end with 12.11.2004
#--------------------------------------------------
#INFORMIX Start_Date 38284
#INFORMIX End_Date 38302
#Days between Start and End 18
#------- and now the way back -----------------
#----------------------------------------------
#Start_Date 25.10.2004
#End_Date 12.11.2004

More informations to idate.sc

My english ist not so good. So I want to explain the handling again.

idate.sc have one parameter.

STEP1
If you use an integer value like this "idate.sc 38284" you get back the date in this format "25.10.2004" (dd.mm.yyyy)

If you use a date value like this "idate.sc 25.10.2004" (dd.mm.yyyy) you get back an integer value in this format "38284" . Now you can add or subtract this value and give it back to STEP1 to get the date you have manipulate.

Bye

I jus would like to say thanx for all the suggestions thus far.