regex - Regular expression for a date range

Question

If I have a directory structure like this

yyyy/dd/mm/<files>

Is there a way to grep for a string in all files in a given time frame using a regex? For example, I have a time frame: 2010/12/25 - 2011/01/01, I need to grep all files in directories corresponding to dates from 25th december to jan 1st

If I am doing this programmatically, is it better to iterate over the date range and grep files in each yyyy/dd/mm directory than to use a regex to do this? Or would it not make a difference?

Answer 1

In your case, it's simple enough:

(?:2010/12/(?:3[01]|2[5-9])|2011/01/01)

will match a string that contains a date in the range you specified. But generally, regexes are not a good fit for matching date ranges. It's always a possibility, but rarely a good one.

For example, for the range 2003/04/25-2011/04/04, you get

(?:
2003/04/(?:30|2[5-9])|
2003/(?:(?:0[69]|11)/(?:30|[12][0-9]|0[1-9])|(?:0[578]|1[02])/(?:3[01]|[12][0-9]|0[1-9]))|
2011/04/0[1-4]|2011/(?:02/(?:[12][0-9]|0[1-9])|0[13]/(?:3[01]|[12][0-9]|0[1-9]))|
(?:2010|200[4-9])/(?:02/(?:[12][0-9]|0[1-9])|(?:0[469]|11)/(?:30|[12][0-9]|0[1-9])|(?:0[13578]|1[02])/(?:3[01]|[12][0-9]|0[1-9]))
)

If I had to do something like this (and couldn't use the creation dates in the file attributes), I would either use RegexMagic (to create the date range regex) and PowerGREP (to do the grepping) if it's a one-time job, but these are only available on Windows. If I had to do this more often, I'd write a small Python script that walks through my directory tree, parses the date for each directory, checks if it's in range, and then looks at the files in that directory.