带有空数据的 --line-regexp 选项 [英] --line-regexp option with null data

问题描述

考虑这个命令:

printf 'alpha
bravo
charlie
' | grep --line-regexp --quiet bravo

grep 看到由换行符分隔的 3 行，并匹配 bravo 行.现在考虑这个命令:

grep sees 3 lines separated by newline, and matches the bravo line. Now consider this command:

printf 'alphabravocharlie' | grep --line-regexp --quiet bravo

我的想法告诉我，因为我没有使用过--null-data，所以grep应该会看到1 甚至 0 行由换行符分隔，并且无法匹配 bravo 后跟新队.但是它没有，它就像第一个命令一样成功，为什么这是?

My thinking tells me that because I have not used --null-data, grep should see 1 or even 0 lines separated by newline, and fail to match a bravo followed by newline. However it does not, it succeeds just like the first command, why is this?

推荐答案

这种行为 是在 Grep 2.21 中引入的:

This behavior was introduced with Grep 2.21:

搜索二进制数据时，grep 现在可以将非文本字节视为行终结者.这可以显着提高性能.

When searching binary data, grep now may treat non-text bytes as line terminators. This can boost performance significantly.

那么现在发生的事情是对于二进制数据，所有非文本字节(包括换行符)被视为行终止符.如果你想改变这个行为，您可以:

So what happens now is that with binary data, all non-text bytes (including newlines) are treated as line terminators. If you want to change this behavior, you can:

• 使用--text.这将确保只有换行符是行终止符

• use --text. This will ensure that only newlines are line terminators

使用--null-data.这将确保只有空字节是行终止符

use --null-data. This will ensure that only null bytes are line terminators

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