I have added a tip to the date faq entry. It hasn't been an faq but but seemed useful just the same.
http://www.gnu.org/software/coreutils/faq/#The-date-command-is-not-working-right_002e Tip: GNU date itself doesn't include any direct support for finding days between dates. But it can be used as part of a script to find this information. The technique is to convert each date to an integer value such as a Julian Day Number or seconds since the Unix epoch 1970-01-01 00:00:00 UTC and then do take the difference and then convert the seconds to days. Use Unix seconds is very convenient due to the %s format. Here is an example. date1="2008-01-01" date2="2010-06-21" date1seconds=$(date -d "$date1 12:00" +%s) date2seconds=$(date -d "$date2 12:00" +%s) totalseconds=$(( $date2seconds - $date1seconds )) secondsperday=86400 days=$(( $totalseconds / $secondsperday )) echo "There were $days days between $date1 and $date2" And of course that can be considerably compacted by applying the constructs inline but this is not as illustrative and so was expanded out in the above example. Here is a compact version. $ echo Days between dates: $(( ( $(date -d "2010-06-21 12:00" +%s) - $(date -d "2008-01-01 12:00" +%s) ) / 86400 )) Bob
