I want to know how to calculate date-n where date is systems current date and N is number of days i want to add or subtract.
I am able to do get yesterday's date but dont know how to add or subtract no of days to get desired date :
date_dir=`date +%Y-%m-%d -d yesterday` echo "$date_dir" Thanks
You can supply an argument '-N days' to the -d option:
$ date +%Y-%m-%d -d '-42 days' # This would subtract 42 days from the current date 2013-10-30 $ date +%Y-%m-%d -d '+42 days' # This would add 42 days to the current date 2014-01-22 and assign the result to a variable:
$ date_dir=$(date +%Y-%m-%d -d '-42 days') $ echo $date_dir 2013-10-30 
date +%Y-%m-%d -d '42 days ago'. It's worth nothing that all these examples are with the GNU implementation of date. In BSD and UNIX this typically doesn't work, but sometimes the GNU version is also installed as gdate`.
linux, it seemed safe to assume that GNU date was being used.var=`date +%s`; date=`date --date=@$var +%Y-%m-%d` echo $date you can add/subtract no of days you need. just remember it is in seconds
From man pages:
%s seconds since 1970-01-01 00:00:00 UTC
Convert seconds since the epoch (1970-01-01 UTC) to a date
$ date --date='@2147483647'
edit: devNull provided better answer
