Ruby: How to determine if file being read is binary or text

Question

I am writing a program in Ruby which will search for strings in text files within a directory - similar to Grep.

I don\'t want it to attempt to search in binary files bu

Answer 1

libmagic is a library which detects filetypes. For this solution I assume, that all mimetype's which start with text/ represent text files. Eveything else is a binary file. This assumption is not correct for all mime types (eg. application/x-latex, application/json), but libmagic detect's these as text/plain.

require "filemagic"

def binary?(filename)
  begin
    fm= FileMagic.new(FileMagic::MAGIC_MIME)
    !(fm.file(filename)=~ /^text\//)
  ensure
    fm.close
  end
end

Answer 2

gem install ptools
require 'ptools'
File.binary?(file)

Answer 3

An alternative to using the ruby-filemagic gem is to rely on the file command that ships with most Unix-like operating systems. I believe it uses the same libmagic library under the hood but you don't need the development files required to compile the ruby-filemagic gem. This is helpful if you're in an environment where it's a bit of work to install additional libraries (e.g. Heroku).

According to man file, text files will usually contain the word text in their description:

$ file Gemfile
Gemfile: ASCII text

You can run the file command through Ruby can capture the output:

require "open3"

def text_file?(filename)
  file_type, status = Open3.capture2e("file", filename)
  status.success? && file_type.include?("text")
end