title: PHP reverse regex match
body: <p>I am in a real trouble here to read a large txt file (around 12mb) with PHP. I have to match a regex, and then search for the first another regex occurrence backwards this matched regex, and then extract the string between these two matches. Here is a real example:</p>
  
  <pre><code>PROCESSO:583.00.2012.105981
  No ORDEM:01.19.2012/000154
  CLASSE:PROCEDIMENTO SUMÁRIO (EM GERAL)
  REQUERENTE:ASSETJ ASSOCIAÇÃO DOS SERVIDORES DO TRIBUNAL DE JUSTIÇA DO ESTADO DE SÃO PAULO
  ADVOGADO:273919/SP - THIAGO PUGINA
  Requerido:TIM CELULAR S/A E OUTRO
  VARA:19a. VARA CÍVEL
  
  PROCESSO:583.00.2012.105970
  No ORDEM:01.07.2012/000134
  CLASSE:PROCEDIMENTO ORDINÁRIO (EM GERAL)
  REQUERENTE:CARLOS NEUMANN
  ADVOGADO:79117/SP - ROSANA CHIAVASSA
  Requerido:SUL AMÉRICA SEGURO SAÚDE S/A
  VARA:7a. VARA CÍVEL
  </code></pre>
  
  <p>The script should find this code: 273919/SP (regex: [0-9]{6}/SP)
  Check backwards for the code: 583.00.2012.105981 (regex: [0-9]{3}.[0-9]{2}.[0-9]{4}.[0-9]{6})</p>
  
  <p>And then get all the text between it.</p>
  
  <p>I can't do a preg_match with both of those regex at the same pattern because through the file some of the blocks have more than one 273919/SP type and it would mess up with everything</p>
  
  <p>What can I do? Do you have any ideas?</p>
  
  <p>Sorry if my regex is crappy, I am new at it and it is very difficult to learn :P</p>
  
  <p>EDIT:</p>
  
  <p>Please check another form that the code appears:</p>
  
  <pre><code>583.00.2012.100905-6/000000-000 - no ordem 82/2012 - Procedimento Sumário (em geral) - JOSE APARECIDO DOS
  SANTOS X SEGURADORA LIDER DOS CONSORCIOS DO SEGUROS DPVAT S/A - Fls. 79 - Demonstre o autor, por meio
  de documento idôneo (declaração de bens e renda e comprovante de pagamento), a necessidade de obtenção do benefício
  da justiça gratuita, a fim de ser cumprido o disposto no artigo 5o, LXXIV da CF. Após, tornem os autos conclusos. Int. - ADV
  GUILHERME DIAS GONÇALVES OAB/SP 302632 - ADV TIAGO RAFAEL OLIVEIRA ALEGRE OAB/SP 302811
  </code></pre>
  
  <p>That is my problem. Now I have two occurrences: OAB/SP 302632 and OAB/SP 302811, and I need to get the last one and extract the text between the id 583.00.2012.100905-6/000000-000 and OAB/SP 302811</p>
  
  <p>Those numbers aren't fixed, so I can't do a search for OAB/SP 302811, but OAB\/SP\s\d{6}</p>