$ perl -E 'my $x = "2"; "ab" =~ /.{$x}/ and say "Matched"' Matched #### $ perl -E 'my $x = "{2}"; "ab" =~ /.$x/ and say "Matched"' Matched #### $ perl -E 'my $x = "2}"; "ab" =~ /.{$x/ and say "Matched"' Matched