>> and << only added to visualize.
Command:
ruby -rnokogiri -e 'doc = Nokogiri::HTML.fragment(readlines.join); doc.search("@id").remove; puts doc' sample.html
INPUT #1:
----------------------------------------------------------------------
>>
Foo
Section 1
Section 2
Section 3
Section 4
<<
OUTPUT #1:
----------------------------------------------------------------------
>>
Foo
Section 1
Section 2
Section 3
Section 4
<<
======================================================================
INPUT #2:
----------------------------------------------------------------------
>>
Foo
Section 1
Section 2
Section 3
Section 4
<<
OUTUT #2:
----------------------------------------------------------------------
>>
FooSection 1
Section 2
Section 3
Section 4
<<