trouble adding days to a passed in date string

ne00 · 04-08-2009, 01:33 PM

I'm having trouble figuring out how to use the date command to accept a passed in date string and adding 10 days to it.

I tried the following and it works fine:

Code:

completedate=$(date -d '2009-03-27 + 10 days' +%m-%d)

echo $completedate

Output is 04-06

But when I try to pass in a date string that's entered in from the prompt, I'm having trouble getting it to work.

Code:

read -p "enter date: " xdate

completedate=$(date -d '($xdate) + 10 days' +%m-%d)

echo $completedate

The output is basically taking today's date and adding 10 days to it and ignoring the input date which is 2009-03-27.

Thanks

Dave

colucix · 04-08-2009, 01:36 PM

Remove the unnecessary parentheses around ($xdate) and use double quotes instead of single quotes. The single ones prevent the shell to do the correct variable substitution.

kolargol · 04-08-2009, 01:39 PM

chabge ($xdate) to $xdate and it should work

ne00 · 04-08-2009, 03:09 PM

Thanks for the reply, I gave those a try and still can't get it to work.

For the use of double quotes I tried...

Code:

completedate=$(date -d '"$xdate" + 10 days' +%m-%d)

and

Code:

completedate=$(date -d "$xdate + 10 days" +%m-%d)

Both I received an invalid date error.

and for removing the ()...

Code:

completedate=$(date -d '$xdate + 10 days' +%m-%d)

I received an invalid date error for 'xdate + 10 days'

any other suggestions I can try?

colucix · 04-08-2009, 03:22 PM

The second of your examples should work:

Code:

$ read -p "enter date: " xdate
enter date: 2009-03-27
$ completedate=$(date -d "$xdate + 10 days" +%m-%d)
$ echo $completedate
04-06

The other ones are wrong because of the single quotes around the date string. In that case the string $xdate is interpreted literally, since the single quotes do not let the shell substitute the value to the variable. You can also remove the plus sign, even if I think that's not a problem:

Code:

date -d "$xdate 10 days" +%m-%d

What about running the following? Do you still get an error?

Code:

$ xdate=2009-03-27
$ date -d "$xdate 10 days" +%m-%d

ne00 · 04-08-2009, 04:35 PM

Thank you so much. Works great!