use strict;
my $str = '2017/07/24204301/a-4.png
2017/07/24204318/a-5-e1501986401369.png
2017/11/24211223/questao10branca-172x300.png';
my $regex = qr~/\d{8}(?=/)~p;
my $subst = '';
my $result = $str =~ s~$regex~$subst~rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html