reldate

A small command line utility which returns the relative date in YYYY-MM-DD format. This is helpful when scripting various time relationships.

Example

If today was 2014-08-03 and you wanted the date three days in the past try–

    reldate 3 days

The output would be

    2014-08-06

Time units

Supported time units are

day(s)
week(s)
year(s)

Specifying a date to calucate from

reldate handles dates in the YYYY-MM-DD format (e.g. March 1, 2014 would be 2014-03-01). By default reldate uses today as the date to calculate relative time from. If you use the –from option you can it will calculate the relative date from that specific date.

    reldate --from=2014-08-03 3 days

Will yield

    2014-08-06

Negative increments

Command line arguments traditionally start with a dash which we also use to denote a nagative number. To tell the command line process that to not treat negative numbers as an “option” preceed your time increment and time unit with a double dash.

   reldate --from=2014-08-03 -- -3 days

Will yield

    2014-07-31

Relative week days

You can calculate a date from a weekday name (e.g. Saturday, Monday, Tuesday) knowning a day (e.g. 2015-02-10 or the current date of the week) occuring in a week. A common case would be wanting to figure out the Monday date of a week containing 2015-02-10. The week is presumed to start on Sunday (i.e. 0) and finish with Saturday (e.g. 6).

    reldate --from=2015-02-10 Monday

will yeild

    2015-02-09

As that is the Monday of the week containing 2015-02-10. Weekday names case insensitive and can be the first three letters of the English names or full English names (e.g. Monday, monday, Mon, mon).

Installation

reldate can be installed with the go get command.

    go get github.com/rsdoiel/reldate/...

reldate - generate relative dates in YYYY-MM-DD format