如何在grep中打印模式的起始位置

Question

在python的regex (re)库中，我可以执行re.search("<pattern>", string).start()以获得模式的开始(如果模式存在)。

如何在unix命令行工具grep中执行相同操作?

。如果=";th.n"字符串"somethingwrong">，我希望看到数字5(考虑到以1为基础，但以0为基础的4也可以)

谢谢!

Answer 1

例如:

echo "abcdefghij" | grep -aob "e"

输出:

4:e

:

-b获取字节偏移

-a告诉grep使用输入作为文本

-o输出结果

用你的例子:

echo ""somethingwrong"" | grep -aob "th.n"
4:thin

这适用于多个匹配:

echo "abcdefghiqsdqdqdfjjklqsdljkhqsdlf" | grep -aob "f"
5:f
16:f
32:f

Answer 2

也许Perl一行程序是必须编写Python程序和标准Unix工具的简单性之间的一个令人满意的折衷。

给定这个文件:

$ cat foo.txt
This thing
that thing
Not here
another thing way over here that has another thing and a third thing
thank you.

可以运行以下Perl一行代码:

$ perl -lne'while(/th.n/g){print $.," ",$-[0]," ",$_;}' foo.txt
1 5 This thing
2 5 that thing
4 8 another thing way over here that has another thing and a third thing
4 45 another thing way over here that has another thing and a third thing
4 63 another thing way over here that has another thing and a third thing
5 0 thank you.

另外，grepllike搜索工具ack(我编写的)有一个--column选项来显示列:

$ ack th.n --column foo.txt /dev/null
foo.txt
1:6:This thing
2:6:that thing
4:9:another thing way over here that has another thing and a third thing
5:1:thank you.

或者使用--nogroup选项，以便文件名出现在每行。

$ ack th.n --column --nogroup foo.txt /dev/null
foo.txt:1:6:This thing
foo.txt:2:6:that thing
foo.txt:4:9:another thing way over here that has another thing and a third thing
foo.txt:5:1:thank you.

我必须添加对/dev/null的搜索，因为如果只搜索一个文件，ack的输出将会不同。

ripgrep也有一个--column选项。

$ rg --column --line-number th.n foo.txt
1:6:This thing
2:6:that thing
4:9:another thing way over here that has another thing and a third thing
5:1:thank you.