Shell Programming and Scripting

I want to change a date from format dd-mmm-yyyy to mm/dd/yyyy. Is there a way to do this with sed or do you have to write a case statement to convert JAN to 01? Thanks

On FreeBSD:

Code:

date -j -f "%d-%b-%Y" "27-Mar-2008" "+%m/%d/%Y"

Maybe I should have mentioned that I am using korn shell. I get an error when using that.

> date "%d-%b-%Y" "27-Mar-2008" "+%m/%d/%Y"
date: bad conversion

Next time you should mention your shell and your OS from the beginning

Code:

echo "28-Mar-2008" | date -d - "+%m/%d/%Y"

or..

Code:

#!/bin/ksh
d="28-Mar-2008"
date -d $d "+%m/%d/%Y"

You should take a look over man date anyway.

Not all date implementations have all this fancy shmancy stuff. As a matter of fact, on HP-UX or Sun, you should be thankful that it even displays today's date.

If you can't get a good date (sorry, couldn't resist), then yes, sed (or cut, or awk, or perl, or nearly any programming language you happen to know the basics of) can be used to move around parts within the string.

(True story from real life: I had a colleague who needed to remove duplicate lines from a file. I intercepted him when he had exported the file to his University account and loaded it into SPSS which he was more familiar with, but couldn't quite get to do this precise task.)

But yes, you need the month name to number mapping somehow. somebody posted one awk solution the other day, but I can't seem to find it now. If the input is just the date then twelve lines of sed will do it.

Code:

# echo "dd-mmm-yyyy" | awk 'BEGIN{FS="-";OFS="/"}{print $2,$1,$3}'
mmm/dd/yyyy

Add to the BEGIN { m[jan] = 1; m[feb] = 2; ... etc } and there you have it. Like I said, somebody posted code like this I think only yesterday, but I wasn't able to bring it up with a search.