grep 仅前 n 行

Question

I'm facing a problem greping the right date within a letter as a document. Reason is to grep the date of document creation and not any further date within the text.

Usaly the dokument hold information about the company, my address, customer number, bill number.... and the date by when it was created.

Mayby a greeting and/or text maybe within dates again.

Often the date at begin of the document has different look as following.

3. December 1999 instead of 3.12.1999 as example.

If I grep the date in case of pattern

'(([0-9][0-9]{,1}\.)\s+('Januar'|'Februar'|'März'|'April'|'Mai'|'Juni'|'Juli'|'August'|'September'|'Oktober'|'November'|'Dezember')\s+([1-9][0-9][0-9][0-9]{1,}))'

sometimes get the wrong date as creation date. Reason is the different writing of dates in the documents. Example 1 is what I usualy get and it works fine as I search for the date (creation date) with correct pattern. Example 2 is in problem as I get a date, but it's NOT creation date which would be the 1st date. I get instead another date matching the pattern out from the text.

Example 1

Example 2

I could use different pattern '(([0-9][0-9]{,1}\.)([0-9][0-9]{,1}\.)([1-9][0-9][0-9][0-9]{1,}))' grepping the correct date in example 2 but then I would get same issue for example 1.

My idea was to search in first n lines only if pattern match take the date otherwise use different pattern. I don't get the rule for pdfgrep using the first n lines only what would give me the possibility to use different pattern.

Has anybody an idea how to fix it?

Cheers, bdream

Answer 1

With GNU grep:

-m NUM : Stop reading a file after NUM matching lines.

Answer 2

Alternatively to GNU grep learn to use GNU gawk , specifically designed for such tasks.

Consider also learning python or GNU guile (then read SICP ).