Loop from start date to end date in Mac OS X shell

问题:

The date function on OS X (Snow Leopard) does not have the --date option like the GNU version and I am not able to figure out how to get the equivalent of the following on OS X:

startdate=2010-01-01
enddate=2010-01-31
foldate="$startdate"

until [ "$foldate" == "$enddate" ]
do
    # do something with the date here - like pass it as a parameter to a command
    foldate=`/bin/date --date "$foldate 1 day" +%Y-%m-%d`
done

SOLVED with answers from SiegeX:

startdate=2010-01-01
enddate=2010-01-31

sDateTs=`date -j -f "%Y-%m-%d" $startdate "+%s"`
eDateTs=`date -j -f "%Y-%m-%d" $enddate "+%s"`
dateTs=$sDateTs
offset=86400

while [ "$dateTs" -le "$eDateTs" ]
do
  date=`date -j -f "%s" $dateTs "+%Y-%m-%d"`
  printf '%s\n' $date
  dateTs=$(($dateTs+$offset))
done

回答1:

Read your date's manpage by running man date and look at the -v option. Here is an excerpt:

-v Adjust (i.e., take the current date and display the result of the adjustment; not actually set the date) the second, minute, hour, month day, week day, month or year according to val. If val is preceded with a plus or minus sign, the date is adjusted forwards or backwards according to the remaining string, otherwise the relevant part of the date is set. The date can be adjusted as many times as required using these flags. Flags are processed in the order given.