Why is Perl regex \K not excluding the pattern matched before \K?

Question

I have a file called test.txt with the following:

> Last login: Mon Jul 13 05:09:33 2020 You have mail.   
> ******************************
> cat, you ha         


        

Answer 1

You may want to say:

perl -ne 'print $& if /.+@.+\K:/' test.txt

which outputs:

:

• The statement print if CONDITION is equivalent to print $_ if CONDITION and just prints the line without modifications if the CONDITION meets. Please use $& instead.
• The second argument cat@sampleserver2: will cause an error saying "Can't open cat@sampleserver2:: No such file or directory."