Question

I have many files containing date extensions. For example, today’s file would be named

filename.20101118

and format is yyyymmdd. I would like to list/grep/etc for all dated files.

Answer 1

Do you mean just something like this ?

/filename\.[12][90][0-9][0-9][01][0-9][0-3][0-9]/

Note that this matches non-valid dates, too.

or, more generalized:

/[a-zA-Z0-9_]+\.[12][90][0-9][0-9][01][0-9][0-3][0-9]/

instead of [a-zA-Z0-9_] you can use whatever characters your filename can contain.