[Practical.Vim(2012.9)].Drew.Neil.Tip98 学习摘要

Delete Lines Containing a Pattern

Combining the :global and :delete commands allows us to cut down the size of a file rapidly. We can either keep or discard all lines that match a {pattern}.
结合:global和:delete命令可以快速的裁剪文件。我们可以保留或着去掉匹配{pattern}的行。
测试文件如下

Delete Matching Lines

What if we wanted to throw away everything except for the contents of each <a> tag? In this file, the contents of each link appear on a line of their own, while every other line of the file contains either an opening or a closing tag.
So if we can devise a pattern that matches HTML tags, we could use it with the :global command to reject any lines that match the pattern. These commands would do the trick:
如果我们要删除除标签<a> 包含内容之外的其他所有行，我们可以利用:global命令来删除。

/\v\<\/?\w+>
 :g//d

If we run these two commands on the Vimcasts.org archive file, we ’re left with this:
在测试文档中执行上面的命令，可以得到：

Show invisibles
Tabs and Spaces
Whitespace preferences and filetypes

The regular expression uses very magic mode (covered in Tip 73). It matches an opening angle bracket (\<), followed by an optional forward slash (\/?), and then one or more word characters (\w+) followed by an end-ofword delimiter (>). This is not an all-purpose tag-matching regex, but it’s good enough for this particular case.
上面的正则表达式利用了 verymagic模式。它匹配了<符号，前面加**进行转置，后跟0个或1个/** ，同样要用\进行转置，随后是一个或多个word，\w表示word，+表示1个或多个，最后还有>。
我们要找的就是标签<某个word>

Keep Only Matching Lines

This time we ’ll switch things around. The :vglobal command, or :v for short, does the opposite of the :g command. That is, it executes a command on each line that does not match the specified pattern. The lines containing the URLs are easy to identify: they all contain the href attribute. We can select only those lines by running this command:
这次我们要在不匹配特定pattern的每一行文本执行命令。包含URL的行非常容易区分，都包含href属性，我们就可以执行命令如下

 :v/href/d

This can be read as “Delete each line that doesn’t contain href. ” The result looks like this:
这句命令可以翻译为“删除所有不含有href的行”，结果为

<a href="/episodes/show-invisibles/">
<a href="/episodes/tabs-and-spaces/">
<a href="/episodes/whitespace-preferences-and-filetypes/">