Ruby 在文件中查找字符串并打印结果
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/10832440/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Ruby find string in file and print result
提问by Matheus Moreira
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:
我已经很长时间没有使用 ruby 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：
#!/usr/bin/env ruby
f = File.new("file.txt")
text = f.read
if text =~ /string/ then
puts test
end
I want to determine what the "document root" (routes) is in config/routes.rb
我想确定 config/routes.rb 中的“文档根”（路由）是什么
If I print the string, it prints the file.
如果我打印字符串，它会打印文件。
I feel dumb that I don't remember what this is, but I need to know.
我觉得很愚蠢，我不记得这是什么，但我需要知道。
Hopefully, I can make it print this:
希望我可以让它打印这个：
# Route is:
blah blah blah blah
回答by Matheus Moreira
File.open 'file.txt' do |file|
file.find { |line| line =~ /regexp/ }
end
That will return the first line that matches the regular expression. If you want allmatching lines, change findto find_all.
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find为find_all.
It's also more efficient. It iterates over the lines one at a time, without loading the entire file into memory.
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。
Also, the grepmethod can be used:
此外，该grep方法可以用于：
File.foreach('file.txt').grep /regexp/
回答by iain
The simplest way to get the root is to do:
获得根的最简单方法是：
rake routes | grep root
If you want to do it in Ruby, I would go with:
如果你想在 Ruby 中做到这一点，我会选择：
File.open("config/routes.rb") do |f|
f.each_line do |line|
if line =~ /root/
puts "Found root: #{line}"
end
end
end
回答by gmaliar
Inside textyou have the whole file as a string, you can either match against it using a .matchwith regexp or as Dave Newton suggested you can just iterate over each line and check.
Something such as:
在内部，text您将整个文件作为一个字符串，您可以使用.matchwith regexp匹配它，或者按照 Dave Newton 的建议，您可以遍历每一行并进行检查。例如：
f.each_line { |line|
if line =~ /string/ then
puts line
end
}
