You could do this at the prompt with something like 
perl -ne 'print if / (\S) \1 \1$/' data.txt

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assuming your file is named data.txt. If you want to save that to a second file then 
perl -ne 'print if / (\S) \1 \1$/' data.txt > second.file

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The -ne flags are very handy at the command line. The -e flag means "evaluate this code". The -n flag doesn't have a convenient mnemonic but wraps a loop around the code for every line of input.

For example...

perl -e 'print "hello world\n"'

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... is a nice canonical example. And...

perl -ne 'print "hello world. Look at this: $_"' data.txt

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...will prepend text to every line of data.txt and print the result.

more docs for command line options at perlrun

more docs for regular expressions at perlre

In reply to Re: ignore some delimiters while using split by perlpie
in thread ignore some delimiters while using split by nurulnad

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