Read your file into the long string as before, process each sentance in a foreach loop using a global regular expression with a capture, only printing the sentance if it matches.

use strict;
use warnings;

my $str = <DATA>;

foreach my $sentance ( $str =~ m{([^.]+\.)\s?}g )
{
    next unless $sentance =~ m{^Nullam\b.*\b(?:augue|libero)};
    print qq{$sentance\n};
}

__END__
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla commodo
+ dignissim dui. Mauris egestas nunc non justo. Praesent consectetur p
+haretranulla. Mauris sed magna. Fusce sit amet lectus. Aliquam bibend
+um mi sollicitudin nulla. Pellentesque volutpat. Morbi ac nibh ut mau
+ris tempor molestie. Nullam sit amet mi at neque lacinia suscipit. Nu
+nc sem erat, porta fermentum, tempus sed, porttitor et, nibh. Nulla t
+urpis orci, egestas eget, lacinia id, tincidunt vel, ligula.Donec sit
+ amet libero. Pellentesque ac felis vel erat interdum elementum. Prae
+sent luctus tellus sit amet velit. Cras lacinia molestie nibh. Suspen
+disse cursus. Sed facilisis magna id nisl blandit malesuada. Cras com
+modo. Nam gravida dolor eu purus. Sed et velit. Nulla rhoncus hendrer
+it lectus. Ut nisi. Nam suscipit eros accumsan quam. Nam ornare. Morb
+i a ipsum non urna adipiscing tempus. Duis in dui a enim malesuada te
+mpus. Ut vehicula sollicitudin tellus. Cum sociis natoque penatibus e
+t magnis dis parturient montes, nascetur ridiculus mus. Vivamus gravi
+da adipiscing purus. Phasellus varius nisi et mauris.Lorem ipsum dolo
+r sit amet, consectetur adipiscing elit. Sed ullamcorper erat sit ame
+t magna. Sed porta nisi quis leo. Integer elementum elit vel libero. 
+Fusce vulputate magna sed nisi imperdiet fringilla. Nullam quis augue
+. Suspendisse mauris tortor, sollicitudin non, posuere ut, bibendum i
+d, enim. Aenean id purus. Donec pretium. Nam blandit nisi at elit. Fu
+sce ac erat et quam porta eleifend. Sed imperdiet bibendum nulla. Mor
+bi varius sagittis justo. Phasellus hendrerit ullamcorper risus. Phas
+ellus nisl ante, ullamcorper nec, pellentesque quis, rutrum in, ligul
+a. Cum sociis natoque penatibus et magnis dis parturient montes, nasc
+etur ridiculus mus.Nulla facilisi. Suspendisse commodo diam ut dui. M
+auris neque est, consequat vitae, vestibulum vel, sodales quis, mauri
+s. Ut pharetra mauris sit amet metus. Nulla hendrerit sapien eleifend
+ massa. Aliquam lacinia tempus augue. Nullam congue congue lectus. Su
+spendisse nulla lectus, rhoncus eu, dapibus et, tempus ut, sapien. Ve
+stibulum ante ipsum primis in faucibus orci luctus et ultrices posuer
+e cubilia Curae; Cras libero. Curabitur scelerisque metus quis tortor
+ facilisis ornare. Aenean sodales ante vitae eros. Suspendisse potent
+i. Integer auctor nisi a diam. Mauris tristique laoreet leo. Integer 
+eu tortor. Quisque lacinia mauris et elit.Cum sociis natoque penatibu
+s et magnis dis parturient montes, nascetur ridiculus mus. Nam luctus
+ mauris nec lorem. Suspendisse leo est, ornare quis, volutpat quis, i
+mperdiet quis, diam. Duis vestibulum. Vestibulum iaculis diam in maur
+is. Donec sollicitudin. Proin justo turpis, vestibulum in, lacinia si
+t amet, ultrices sit amet, dolor. Sed placerat, leo non facilisis dic
+tum, lectus ligula vulputate purus, id varius metus turpis sed tortor
+. Praesent eu erat ut justo imperdiet cursus. Donec et magna id diam 
+pulvinar sodales. Sed eu libero sit amet tortor mollis pretium. Nulla
+m a orci. Proin ac massa.

[download]

The output.

Nullam quis augue.

[download]

I hope this is useful.

Cheers,

JohnGG

In reply to Re: Parse a large string by johngg
in thread Parse a large string by 1001jrlight

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