use IPC::Open2 qw( open2 );

my @cmd = (
    sqlplus => (
        '-S',
        '/as' => 'sysdba',
    )
);

local *TO_SQLPLUS;
my $pid = open2('>&STDOUT', *TO_SQLPLUS, @cmd)
    or die("Can't launch sqlplus: $!\n");

print TO_SQLPLUS <<'__EOI__';
...
foo
bar
...
__EOI__

close(TO_SQLPLUS);
waitpid($pid,0);