尝试从巨大的xml文档中提取特定的标记/属性

Question

我试图在Linux系统上使用xmllint从一个巨大的(超过150万行) xml文档中提取一些特定的数据，但对xmllint语法不太熟悉。我一直在使用grep和awk来做这件事，效率很低，但我发现这个系统有xmllint实用程序(我从未使用过)，我想既然xml结构良好，应该有一种方法来直接访问数据。我已经包含了xml文档的一个片段，但是在解析它的过程中，我导致了xmllint出现解析器错误，尽管我认为它是正确的。我想，如果您足够精通xmllint来回答我的问题，那么您可能很容易找出解析器错误。

基于网络搜索，我尝试了以下语法：

cat //*/@index' | xmllint --shell stub.xml (which does return ALL of the "indexes")
and
test=$(xmllint --debug --xpath "//PTC/BPSETS/BPSET/BPS" stub.xml) (which does dump the entire BPS entry)
and
xmllint --xpath "string(//PTC/BPSETS/BPSET/@b95)" stub.xml (returns no values)

Here is the xml snippet as best as I can trim it down:

<?xml version="1.0" encoding="utf-8"?>
<PTC version="2.0" cls="2">
  <BPSETS>
    <BPSET define="b95">
      <BPS define="88lmax">
        <CRIT>
          <MNBS lmt="88" />
          <MXBS lmt="88" />
          <MXBT red="Y" />
        </CRIT>
        <PNS>
          <PN index="0" atv="1" bf="32203506">
            <AWD cpbt="390">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
          <PN index="1" atv="1" bf="24237243">
            <AWD cpbt="390">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
          <PN index="2" atv="1" bf="8136575">
            <AWD cpbt="390">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
        </AWD>
      </PN>
          <PN index="688" atv="1" bf="1183872">
            <AWD cpbt="50" />
          </PN>
        </PNS>
      </BPS>
      <BPS define="88l6">
        <CRIT>
          <MNBS lmt="88" />
          <MXBS lmt="88" />
          <MXBT lmt="6" />
          <MNBT lmt="6" />
        </CRIT>
        <PNS>
          <PN index="0" atv="1" bf="28073582">
            <AWD cpbt="150">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
          <PN index="1" atv="1" bf="16686973">
            <AWD cpbt="150">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
    </PNS>

      </BPS>
      <BPS define="88l4">
        <CRIT>
          <MNBS lmt="88" />
          <MXBS lmt="88" />
          <MXBT lmt="4" />
          <MNBT lmt="4" />
        </CRIT>
        <PNS>
          <PN index="0" atv="1" bf="31342257">
            <AWD cpbt="50">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
          <PN index="1" atv="1" bf="13761775">
            <AWD cpbt="50">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
        </PNS>
      </BPS>
      <BPS define="88l2">
        <CRIT>
          <MNBS lmt="88" />
          <MXBS lmt="88" />
          <MXBT lmt="2" />
          <MNBT lmt="2" />
        </CRIT>
        <PNS>
          <PN index="0" atv="1" bf="16291759">
            <AWD cpbt="10">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
          <PN index="1" atv="1" bf="15032283">
            <AWD cpbt="10">
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
        </PNS>
      </BPS>
      <BPS define="88l1">
        <CRIT>
          <MNBS lmt="88" />
          <MXBS lmt="88" />
          <MXBT lmt="1" />
          <MNBT lmt="1" />
        </CRIT>
        <PNS>
          <PN index="0" atv="1" bf="33278739">
            <AWD>
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
          <PN index="1" atv="1" bf="7261567">
            <AWD>
              <BUNS ptgp="bn38" bdx="38" fawd="1" />
              <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
            </AWD>
          </PN>
          <PN index="896" atv="1" bf="101540">
            <AWD cpbt="10" />
          </PN>
          <PN index="897" atv="1" bf="3680792">
            <AWD cpbt="10" />
          </PN>
          <PN index="898" atv="1" bf="25776896">
            <AWD cpbt="10" />
          </PN>
        </PNS>
      </BPS>
    </BPSET>

    <BPSET define="b94" use="b95">
      <BPS define="88mx">
        <PNS>
          <PN index="422" atv="1" bf="11692089">
            <AWD cpbt="9000" />
          </PN>
          <PN index="424" atv="1" bf="12200338">
            <AWD cpbt="7200" />
          </PN>
          <PN index="427" atv="1" bf="24210225">
            <AWD cpbt="6000" />
          </PN>
       </PNS>
      <BPS>
    </BPSET>

  </BPSETS>
</PTC>





What I really need is a query that returns all the attribute's contained in a specific element  under a specific index e.g.:


<!-- language: lang-xml -->

    <PTC version="2.0" cls="2">
      <PN index="0" atv="1" bf="32203506">
        <AWD cpbt="390">
          <BUNS ptgp="bn38" bdx="38" fawd="1" />
          <BUNS ptgp="bn39" bdx="39" fawd="1" awby="38" />
        </AWD>
      </PN>


A query that given a PN index value (e.g. 0) would return the values of bf and cbpt…

If it were an sql query the xmllint query I'm looking for would be something like:
```sql

从PTC.BPSETS.BPSET.BPS.PNS.PN中选择bf，cbpt

其中BPS = "b95“，BPS= 88lmax，PN.index = 0。

如果你明白我的意思的话。这里的任何指导都很感谢。谢谢。

Answer 1

进一步的研究和实验表明这是所需的语法：

stub.xml 'cat //PTC/BPSETS/BPSET@define="b95"/BPS@define="88lmax"/PNS/PN@index="0"/AWD/@cpbt‘| xmllint --外壳echo

这将产生所需的数据。