Is there an equivalent command for doing things like 147 days from today or days...

spiffytech · on Sept 29, 2021

WolframAlpha works well for those types of calculations.

bewuethr · on Sept 29, 2021

With GNU date (but not the BSD-based macOS date, I believe), and not all that convenient for "days since":

  $ date -d 'today + 147 days' +%F
  2022-02-23
  
  $ echo $(( ($(date +%s) - $(date -d '2021-06-21' +%s)) / 86400 ))
  100
  
  $ date -d '2021-08-15 + 88 days' +%F
  2021-11-11

pajko · on Sept 29, 2021

https://www.timeanddate.com/date/dateadded.html

dhosek · on Sept 29, 2021

To clarify, I was thinking a quick command line thing. Right now, I do it in a browser (both DuckDuckGo and Google produce the answer easily enough).

zadwang · on Sept 29, 2021

The unix date command does this.

randomswede · on Sept 30, 2021

Well, GNU date does, BSD date may or may not.

Linux box:

  $ date -d 'now + 4711 days ago'
  Thu Nov  6 06:57:20 UTC 2008
  $ date --version
  date (GNU coreutils) 8.30
  Copyright (C) 2018 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later 
  <https://gnu.org/licenses/gpl.html>.
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.

  Written by David MacKenzie.

Mac:

  % date -d 'now + 4711 days ago'
  usage: date [-jnRu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ... 
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

I also seem to be unable to pull a version out of the Mac's date command.

mark-r · on Sept 29, 2021

I use the Python datetime module for stuff like that. Excel can be useful too, since it treats dates as a number of days.