egrep：如何搜索包含双引号的文本（win7 cmd窗口）

Question

I'm trying to make a TOC in my HTML file by searching for all HTML tags that contain one of three classes: article, section, and subsection.

I'm using GNU grep 2.4.2 in a Windows 7 cmd window. Now I've read at least 12 pages from my Google search and tried 20+ permutations of my grep command. I'm trying to find classes in my HTML file. Luckily in my HTML file there is only one HTML tag per line in the HTML file, which simplifies things.

I made a cmd batch file and tried running this and got various errors. I've tried escaping the double quotes, and not escaping them. I tried escaping the parens and not escaping them. I've tried different switches, with and without -E, etc. This is the regex I need to search for on every line and print the lines that match.

/class="\\(article\\|section\\|subsection\\)"/

This is one of my later grep attempts.

grep -i -E 'class="\\(article\\|section\\|subsection\\)"' ch18IP.htm

In this example I'm not getting any lines returned nor any error message. What am I doing wrong here?

Thank you!

Answer 1

You have three problems:

1) double quote " literals must be escaped as \\" when using grep on windows.

2) meta-characters ( , ) , and | should only be escaped as \\( , \\) , and \\| when using basic mode. The -E exended regex option uses the more traditional unescaped form. This is documented at http://www.gnu.org/software/grep/manual/html_node/Basic-vs-Extended.html

3) If a parameter requires quoting on Windows, then double quotes are used, not single quotes. But in this case, enclosing quotes are not required, and would actually get in the way. I'll explain this later in the answer.

I also suggest that you add a word boundry assertion \\b before class so that you don't mistakenly match something like subclass .

So either of the following should work:

grep -i -E \bclass=\"(article|section|subsection)\" ch18IP.htm
grep -i \bclass=\"\(article\|section\|subsection\)\" ch18IP.htm

It gets tricky if you want to enclose your search argument in quotes because the search term also includes quote literals, as well as poison characters like | that have special meaning to the cmd "shell". So you may end up having to escape some characters for both grep and cmd.exe. See https://stackoverflow.com/a/19816688/1012053 for more info.

In your case, here are two options for how you could quote your search term for Windows.

grep -i -E ^"\bclass=\"(article|section|subsection)\"^" ch18IP.htm
grep -i -E "\bclass=\"(article^|section^|subsection)\"" ch18IP.htm

That last form looks mighty weird if you decide to use the basic regex:

grep -i "\bclass=\"\(article\^|section\^|subsection\)\"" ch18IP.htm

Answer 2

Getting double-quotes as input on Windows cmd.exe command line is notoriously problematic. See if this works for you: https://www.gnu.org/software/gawk/manual/html_node/DOS-Quoting.html