Perl/regex to remove first 3 lines and last 3 lines of a string

Question

I was looking to build a regex statement to always remove the first 3 lines of the string, and last 3 lines of the string (the middle part could be any n number of lines content). Any clean regex way to acheive this output? (i.e. always strip our first 3 lines and last 3 lines of the string - and preserve the middle part, which could be a variable # of lines)

Thanks.

e.g.

Input String:

"
1
2
3
<1...n # of lines content>
4
5
6
"

To desired output string:

"<1..n # of lines content>"

Answer 1

The previously given solutions are really complex! All one needs is

s/^(?:.*\n){1,3}//;
s/(?:.*\n){1,3}\z//;

If you want to accept a lack of trailing newline at the end, you can use

s/\n?\z/\n/;
s/^(?:.*\n){1,3}//;
s/(?:.*\n){1,3}\z//;

or

s/^(?:.*\n){1,3}//;
s/(?:.*\n){0,2}.*\n?\z//;