my $starting_line    = qr{ ^s [^\n]* \n }xsm;  # starts with an 's'
my $intervening_line = qr{    [^\n]* \n }xsm;  # anything
my $ending_line      = qr{   e [ ] p \n }xsm;  # ends with an 'e p'

my $between = 1;

my $line = do { local $/;  <DATA> };  # slurp all the data

$line =~ s{ $start_line ${intervening_line}{$between} $end_line }
          {}gxsm;

##</code><code>##

Random String
s
foo
e f
blah blah
End of file