Ruby 在文件中查找字符串并打印结果 [英] Ruby find string in file and print result

问题描述

我已经很长时间没有使用 ruby​​ 来做这样的事情了，但是，我忘记了如何打开文件、查找字符串以及打印 ruby​​ 找到的内容.这是我所拥有的:

It's been a very long time since I've used ruby for things like this but, I forget how to open a file, look for a string, and print what ruby finds. Here is what I have:

#!/usr/bin/env ruby
f = File.new("file.txt")
text = f.read
if text =~ /string/ then
puts test
end

我想确定 config/routes.rb 中的文档根目录"(路由)是什么

I want to determine what the "document root" (routes) is in config/routes.rb

如果我打印字符串，它会打印文件.

If I print the string, it prints the file.

我不记得这是什么，我感到很愚蠢，但我需要知道.

I feel dumb that I don't remember what this is, but I need to know.

希望我能把它打印出来:

Hopefully, I can make it print this:

# Route is:
blah blah blah blah

推荐答案

File.open 'file.txt' do |file|
  file.find { |line| line =~ /regexp/ }
end

这将返回与正则表达式匹配的第一行.如果您想要所有匹配的行，请更改<代码>查找到find_all.

That will return the first line that matches the regular expression. If you want all matching lines, change find to find_all.

它也更有效率.它一次遍历一行，而不将整个文件加载到内存中.

It's also more efficient. It iterates over the lines one at a time, without loading the entire file into memory.

此外，grep方法:

Also, the grep method can be used:

File.foreach('file.txt').grep /regexp/

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