bash 使用 awk 从一行中提取值
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Use awk to extract value from a line
提问by qu1x0tc
I have these two lines within a file:
我在文件中有这两行：
<first-value system-property="unique.setting.limit">3</first-value>
<second-value-limit>50000</second-value-limit>
where I'd like to get the following as output using awk or sed:
我想使用 awk 或 sed 将以下内容作为输出：
3
50000
Using this sed command does not work as I had hoped, and I suspect this is due to the presence of the quotes and delimiters in my line entry.
使用这个 sed 命令并没有像我希望的那样工作，我怀疑这是由于我的行条目中存在引号和分隔符。
sed -n '/WORD1/,/WORD2/p' /path/to/file
How can I extract the values I want from the file?
如何从文件中提取我想要的值？
回答by Ashkan
awk -F'[<>]' '{print }' input.txt
input.txt:
输入.txt：
<first-value system-property="unique.setting.limit">3</first-value>
<second-value-limit>50000</second-value-limit>
Output:
输出：
3
50000
回答by Tom Fenech
Looks like XML to me, so assuming it forms part of some valid XML, e.g.
对我来说看起来像 XML，所以假设它是一些有效 XML 的一部分，例如
<root>
<first-value system-property="unique.setting.limit">3</first-value>
<second-value-limit>50000</second-value-limit>
</root>
You can use Perl's XML::Simpleand do something like this:
您可以使用 Perl 的XML::Simple并执行以下操作：
perl -MXML::Simple -E '$xml = XMLin("file"); say $xml->{"first-value"}->{"content"}; say $xml->{"second-value-limit"}'
Output:
输出：
3
50000
If the XML structure is more complicated, then you may have to drill down a bit deeper to get to the values you want. If that's the case, you should edit the question to show the bigger picture.
如果 XML 结构更复杂，那么您可能需要更深入地钻取以获得所需的值。如果是这种情况，您应该编辑问题以显示更大的图景。
回答by jaybee
Ashkan's awksolution is straightforward, but let me suggest a sedsolution that accepts non-integer numbers:
Ashkan 的awk解决方案很简单，但让我建议一个接受非整数的sed解决方案：
sed -n 's/[^>]*>\([.[:digit:]]*\)<.*//p' input.txt
This extracts the number between the first >character of the line and the following <. In my RE this "number" can be the empty string, if you don't want to accept an empty string please add the -roption to sedand replace \([.[:digit:]]*\)by ([.[:digit:]]+).
这将提取>行的第一个字符和下一个字符之间的数字<。在我的 RE 中，这个“数字”可以是空字符串，如果您不想接受空字符串，请将-r选项添加到sed并替换\([.[:digit:]]*\)为([.[:digit:]]+)。
回答by Technext
Using sed:
使用sed：
sed -E 's/.*limit"*>([0-9]+)<.*//' file
Explanation:.*takes care of everything that comes before the string limit
说明：.*处理字符串限制之前的所有内容
limit"*takes care of both the lines, one with limit"and the other one with just limit
limit"*处理两条线，一条线，limit"另一条线limit
([0-9]+)takes care of matching numbers and only numbers as stated in your requirement.
([0-9]+)处理匹配的数字，并且仅处理您的要求中所述的数字。
\1is actually a shortcut for capturing pattern. When a pattern groups all or part of its content into a pair of parentheses, it captures thatcontent and stores it temporarily in memory. For more details, please refer https://www.inkling.com/read/introducing-regular-expressions-michael-fitzgerald-1st/chapter-4/capturing-groups-and
\1实际上是捕获模式的快捷方式。当模式将其全部或部分内容分组到一对括号中时，它会捕获该内容并将其临时存储在内存中。更多详情请参考https://www.inkling.com/read/introducing-regular-expressions-michael-fitzgerald-1st/chapter-4/capturing-groups-and
回答by vks
sed -e 's/[a-zA-Z.<\/>= \-]//g' file
回答by David C. Rankin
The script solution with parameter expansion:
带参数扩展的脚本解决方案：
#!/bin/bash
while read line || test -n "$line" ; do
value="${line%<*}"
printf "%s\n" "${value##*\>}"
done <""
output:
输出：
$ ./ltags.sh dat/ltags.txt
3
50000
