如何找到多行模式匹配(它们必须是首次匹配)? [英] How to find the multiline pattern match (they must be first time match)?

问题描述

我知道这个问题如何跨多行查找模式使用grep吗?但是我认为我的问题更加复杂.所以我需要帮助.

I know this question How to find patterns across multiple lines using grep? But I think my problem is more complicated. So I need help.

我有一个词典文件BCFile作为

boundary
{
    inlet
    {
        type            fixedValue;
        value           uniform (5 0 0);
    }

    outlet
    {
        type            inletOutlet;
        inletValue      $internalField;
        value           $internalField;
    }

    ....
}

我正在编写脚本，以便打印出inlet边界条件fixedValue和outlet边界条件inletOutlet.

I am writing a script so to print out the inlet boundary condition fixedValue, and the outlet boundary condition inletOutlet.

如果我使用cat BCFile | grep "type" | awk '{printf $2}' | tr -d ";"，它将不能正常工作，因为关键字type出现了很多次.

If I use cat BCFile | grep "type" | awk '{printf $2}' | tr -d ";", it won't work as keyword type occurs many times.

如果我使用awk -v RS='}' '/inlet/ { print $4 }' BCFile，它也不起作用，因为关键字inlet也会出现多次.

If I use awk -v RS='}' '/inlet/ { print $4 }' BCFile, it won't work either, because keyword inlet also occurs many times.

我需要一种找到模式的方法，该模式首先搜索关键字inlet，然后搜索最近 {和}.

I need a way to find pattern that first search for key word inlet and then search the closest { and }.

有人知道如何聪明地做到吗?

Anyone knows how to do it smartly?

推荐答案

由于您没有为发布的输入提供预期的输出，我们只是在猜测您想要的输出，但是在GNU awk中如何实现:

Since you didn't provide expected output for the input you posted we're just guessing at what you want output but how about this in GNU awk:

$ cat tst.awk
BEGIN{ RS="\0" }
{
   print "inlet:",  gensub(/.*\yinlet\y[^}]*type\s+(\w+).*/,"\\1","")
   print "outlet:", gensub(/.*\youtlet\y[^}]*type\s+(\w+).*/,"\\1","")
}
$ gawk -f tst.awk file
inlet: fixedValue
outlet: inletOutlet

说明:

RS="\0"

=将Record Separator设置为Null字符串，以便awk将整个文件读取为单个记录.

= set the Record Separator to the Null string so awk reads the whole file as a single record.

gensub(/.*\yinlet\y[^}]*type\s+(\w+).*/,"\\1","")

=查找单词inlet，后跟除}以外的所有字符(因此，您将停在inlet之后的第一个}之前，而不是文件中的最后一个})，然后再搜索单词type，然后是空白.紧随其后的字母数字字符串(\w+)是您要打印的单词，因此请记住它，然后将整个记录替换为保存在\\1中的那个字符串.

= look for the word inlet followed by any characters except a } (so you stop before the first } after inlet instead of the last } in the file) and then the word type followed by white space. The alpha-numeric string after that (\w+) is the word you want printed so remember it and then replace the whole record with just that string as saved in \\1.

设置RS="\0"和gensub()都是特定于gawk的.

Setting RS="\0" and gensub() are both gawk-specific.

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