qr/^(-[5}|-{7})\n$/;

gistfile1.txt

#!/usr/bin/env perl
use strict;
use Test::More;
plan tests => 6;

my $re = qr/^(-{5}|-{7})\n$/;
my $ret;

my $str1 = "-----\n"; # 5
ok(  ($str1 =~ /$re/) );

my $str2 = "-----"; # 5
ok(! ($str2 =~ /$re/) );

my $str3 = "------\n"; # 6
ok(! ($str3 =~ /$re/) );

my $str4 = "------"; # 6
ok(! ($str4 =~ /$re/) );

my $str5 = "-------\n"; # 7
ok(  ($str5 =~ /$re/) );

my $str6 = "-------\n"; # 7
ok(  ($str6 =~ /$re/) );