#!/usr/bin/perl
use strict;
use warnings;

my $element = "coucou";

open (INFILE, "<EXEMPLE.txt");


while (my $line = <INFILE>){
    if ($line =~ /$element/){
    		my $pre=$`;###to get the previous text from the matching text
    		my $post=$';###to get the following text from the matching text        
        print "PREVIOUS:$pre\nFOLLOWING:$post\n";
    }
}

close INFILE;