Running dynamic scripts

@define

DB: Oraclle 11g

OS: AIX 6.1

I need to run sql scripts dynamically and build the following code in file script.sql:

@define.sql

declare

    i int;

    linha char(5);

    conexao char(50);

begin

    for i in 1..&&QUANT_LINHAS loop

        linha := substr('&&ORACLE_SID', 1, 3) || to_char(i);

        conexao := '/cmdlib/oracle/connect/' || '&&ORACLE_SID' || '/connect_' || trim(linha) || '.sql';

        @conexao;

    end loop;

end;

/

In define.sql I have:

DEFINE ORACLE_SID   = BRMB

DEFINE QUANT_LINHAS = 5

When I run the file script.sql get the following error:

SP2-0310: unable to open file "conexao.sql"

How can I fix this?