Iterate through every file in one directory

Question

As others have said, Dir::foreach is a good option here. However, note that Dir::foreach and Dir::entries will always include . and .. (the current and parent directories). You will generally not want to work on them, so you can use Dir::each_child or Dir::children (as suggested by ma11hew28) or do something like this:

Dir.foreach('/path/to/dir') do |filename|
  next if filename == '.' or filename == '..'
  # Do work on the remaining files & directories
end

Dir::foreach and Dir::entries (as well as Dir::each_child and Dir::children) also include hidden files & directories. Often this is what you want, but if it isn't, you need to do something to skip over them.

Alternatively, you might want to look into Dir::glob which provides simple wildcard matching:

Dir.glob('/path/to/dir/*.rb') do |rb_filename|
  # Do work on files & directories ending in .rb
end

This is my favorite method for being easy to read:

Dir.glob("*/*.txt") do |my_text_file|
  puts "working on: #{my_text_file}..."
end

And you can even extend this to work on all files in subdirs:

Dir.glob("**/*.txt") do |my_text_file| # note one extra "*"
  puts "working on: #{my_text_file}..."
end

Dir has also shorter syntax to get an array of all files from directory:

Dir['dir/to/files/*'].each do |fname|
    # do something with fname
end

Dir.foreach("/home/mydir") do |fname|
  puts fname
end

The find library is designed for this task specifically: https://ruby-doc.org/stdlib-2.5.1/libdoc/find/rdoc/Find.html

require 'find'
Find.find(path) do |file|
  # process
end

This is a standard ruby library, so it should be available