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For example, I have date: 4 August 1993 and I want to add 348 days to it, how can I do it in bash?

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up vote 24 down vote accepted

Just use the date command with -d option:

$ date -d "1983-08-04 348 days"
Tue Jul 17 00:00:00 BST 1984

You can change the output format if you want:

$ date -d "1983-08-04 2 days" +%Y-%m-%d
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You can use the OP's date format, too: date -d "4 August 1993 348 days" +"%d %B %Y" – Dennis Williamson Sep 23 '09 at 16:54
According to man date: %F full date; same as %Y-%m-%d – jperelli May 2 '12 at 21:58

In bash on Mac OS X, you can do this:

date -j -v +348d -f "%Y-%m-%d" "1993-08-04" +%Y-%m-%d

Output: 1994-07-18

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Here is a little more complex usage of this:

for i in `seq 1 5`;
  date -d "2014-02-01 $i days" +%Y-%m-%d;

or with pipes:

seq 1 5 | xargs -I {} date -d "2014-02-01 {} days" +%Y-%m-%d
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