In a unix shell, how to get yesterday's date into a variable?

Question

I\'ve got a shell script which does the following to store the current day\'s date in a variable \'dt\':

date \"+%a %d/%m/%Y\" | read dt
echo ${dt}
         


        

Answer 1

If you have access to python, this is a helper that will get the yyyy-mm-dd date value for any arbitrary n days ago:

function get_n_days_ago {
  local days=$1
  python -c "import datetime; print (datetime.date.today() - datetime.timedelta(${days})).isoformat()"
}

# today is 2014-08-24

$ get_n_days_ago 1
2014-08-23

$ get_n_days_ago 2
2014-08-22