compare two txt files - perl

Question

I'm new to Perl. I have two text files and I need to check matching string on both lists.
For example matching strings are:
line - file 1: fe/bla/blablabla/abcdefg
line - file 2: blablabla/abcdefg
There is a match!
In addition, the location (line number) of the matching strings is not the same on both files.
I tried put the lists in arrays and compare the arrays with nested loop, but the running time of the program is huge (the lists contain thousand of lines) and I believe there is another way, less naïve and more productive.
This is the way I put the data in the array:
my $list1 = /path/to/the/file;
open (FILE , '<' , $list1) or die ("Could not open the file");
while ( my $line = <FILE> ) {
chomp ($line);
$list_1[$i] = $line;
$i = $i+1;
}
close FILE;
I did it to the other list as well.
And this is my nested loop.
for ( $k = 0 ; $k < #list_1 ; $k = $k+1 ) {
for ($i = 0 ; $i < #list_2 ; $i = $i+1 ) {
if (index($list_1[$k] , $list_2[$i]) != -1) {
splice (#list_2 , $i , 1);
last;
}
}
}

Answer 1

As long as file2 isn't enormous, the simplest way is to build a regular expression pattern from its contents and check each line in file1 against the pattern.
You don't say what output you want, so I have printed all lines in file1 that have a match in file2.
use strict;
use warnings;
use 5.010;
use autodie;
my ($list1, $list2) = qw( /path/to/list1 /path/to/list2 );
open my $fh, '<', $list2;
my $re = join '|', map { chomp; quotemeta; } <$fh>;
$re = qr/$re/;
open $fh, '<', $list2;
while ( <$fh> ) {
print if /$re/;
}