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I have Linux ( RH 5.3) machine

I need to add/calculate 10 days plus date so then I will get new date (expiration date))

for example

 # date 
 Sun Sep 11 07:59:16 IST 2012

So I need to get

     NEW_expration_DATE = Sun Sep 21 07:59:16 IST 2012

Please advice how to calculate the new expiration date ( with bash , ksh , or manipulate date command ?)

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migrated from serverfault.com Sep 25 '12 at 0:17

This question came from our site for system and network administrators.

3 Answers 3

up vote 17 down vote accepted

You can just use the -d switch and provide a date to be calculated

Sun Sep 23 08:19:56 BST 2012
NEW_expration_DATE=$(date -d "+10 days")
echo $NEW_expration_DATE
Wed Oct 3 08:12:33 BST 2012 
  -d, --date=STRING
          display time described by STRING, not ‘now’

This is quite a powerful tool as you can do things like

date -d "Sun Sep 11 07:59:16 IST 2012+10 days"
Fri Sep 21 03:29:16 BST 2012


TZ=IST date -d "Sun Sep 11 07:59:16 IST 2012+10 days"
Fri Sep 21 07:59:16 IST 2012


prog_end_date=`date '+%C%y%m%d' -d "$end_date+10 days"`
So if $end_date=20131001, $prog_end_date=20131011
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You can use "+x days" as format string:

$ date -d "+10 days"
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$ date -v -1d

In order to get 1 day back date using date command:

$ date -v -1d

It will give (current date -1) means 1 day before .

$ date -v +1d

This will give (current date +1) means 1 day after.

Similarly below written code can be used in place of "d" to find out year,month etc.

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