##############################################################################\r\n# This system is a restricted access system.                               #\r\n# If collected security information reveals possible criminal activity that  #\r\n# exceeds privileges, evidence of such activity may be provided to the rele- #\r\n# vantauthorities for further action. By continuing past this point, you #\r\n# expressly consent to this security monitoring.              #\r\n##############################################################################\r\n\r\nhostname: ~# 

##</code><code>##

use strict;
use Expect;

my $re1 = '(([#%:>~\$\] ])(?!\2)){3,4}|([\w\-\.]*)\$ *$|(\w[@\/]\w|sftp).*?[#%>~\$\]]|^[#%\$>\:]~] *$';
my $test;

open($test,"<","chain.txt");

my $exp = Expect->exp_init($test);

$exp->expect(1,
	[ $re1 => sub {
		my $exp = shift;
		print "Match before : ",$exp->before(),"\n";
		print "Match        : ",$exp->match(),"\n";
		print "Match after  : ",$exp->after(),"\n";
	}]
);

close $test;

##</code><code>##

hans@hans-desktop  ~  perl -v
This is perl 5, version 30, subversion 0 (v5.30.0) built for x86_64-linux-gnu-thread-multi
hans@hans-desktop ~ perl -MExpect -e 'print $Expect::VERSION ."\n";'
1.21

perl test.pl
Match before : ##############################################################################\r\n# This system is a restricted access system.                               #\r\n# If collected security information reveals possible criminal activity that  #\r\n# exceeds privileges, evidence of such activity may be provided to the rele- #\r\n# vantauthorities for further action. By continuing past this point, you #\r\n# expressly consent to this security monitoring.              #\r\n##############################################################################\r\n\r\nhostname
Match        : : ~#
Match after  :  

##</code><code>##

[hans@fedora ~]$ perl -v
This is perl 5, version 34, subversion 0 (v5.34.0) built for x86_64-linux-thread-multi
[hans@fedora ~]$ perl -MExpect -e 'print $Expect::VERSION ."\n";'
1.35

[hans@fedora ~]$ perl test.pl 
Match before : ##############################################################################\r\n# This system is a restricted access system.                             
Match        :   #
Match after  : \r\n# If collected security information reveals possible criminal activity that  #\r\n# exceeds privileges, evidence of such activity may be provided to the rele- #\r\n# vantauthorities for further action. By continuing past this point, you #\r\n# expressly consent to this security monitoring.              #\r\n##############################################################################\r\n\r\nhostname: ~#