date manipulation in shell script

[Paolo Gilli]

Hi,
I, i need to write a shell script where is possible assign to a variable the 'date' value of +n or -n days starting from current date
In other words:
I have:
SYS_DATE="$( date '+%Y%m%d' )"

how can I do something like:
YESTERDAY_DATE= "$( date '+%Y%m%d' )" -1
or
TOMORROW_DATE= "$( date '+%Y%m%d' )" +1

avoid writing date calculation routines?

any ideas?
Tahnkyou

[Patrick Wallek · Accepted solution]

Use a date calc routine that already written. Search for A. Clay Stephensons caljd.sh or caljd.pl script. It should be easy to find in the forums. His script will do exactly what you want.

[Patrick Wallek]

You can download caljd.sh or caljd.pl from here:

http://www.cmve.net/~merijn/#Contrib

It is at the bottom of the page.

[A. Clay Stephenson]

I'll make it easy for you and this is the latest version of caljd.sh.

YESTERDAY_DATE=$(caljd.sh -s -y $(caljd.sh -p 1))
echo "Yesterday = ${YESTERDAY_DATE}"
TOMORROW_DATE=$(caljd.sh -s -y $(caljd.sh -n 1))
echo "Tomorrow = ${TOMORROW_DATE}"

Invoke as caljd.sh -u for full usage and many examples (like previous date plus skip over weekends).

[Arturo Galbiati]

I'm using the mktime SW and it's great!
http://members.rogers.com/weirdways/technogeek/source/mktime/

Art

[Paolo Gilli]

SUPER!!!
Thankyou
Regards
Paolo

[Paolo Gilli]

An other great help by Art!
Thakyou!