Dir

Objects of class Dir are directory streams representing directories in the underlying file system. They provide a variety of ways to list directories and their contents. See also File.

Dir Reference

File

A File is an abstraction of any file object accessible by the program and is closely associated with class IO. File includes the methods of module FileTest as class methods, allowing you to write (for example) File.exist?("foo").

In the description of File methods, permission bits are a platform-specific set of bits that indicate permissions of a file. On Unix-based systems, permissions are viewed as a set of three octets, for the owner, the group, and the rest of the world. For each of these entities, permissions may be set to read, write, or execute the file:

The permission bits 0644 (in octal) would thus be interpreted as read/write for owner, and read-only for group and other. Higher-order bits may also be used to indicate the type of file (plain, directory, pipe, socket, and so on) and various other special features. If the permissions are for a directory, the meaning of the execute bit changes; when set the directory can be searched.

On non-Posix operating systems, there may be only the ability to make a file read-only or read-write. In this case, the remaining permission bits will be synthesized to resemble typical values. For instance, on Windows NT the default permission bits are 0644, which means read/write for owner, read-only for all others. The only change that can be made is to make the file read-only, which is reported as 0444.

Various constants for the methods in File can be found in File::Constants.

File Reference

File::Constants

File::Constants provides file-related constants. All possible file constants are listed in the documentation but they may not all be present on your platform.

If the underlying platform doesn’t define a constant the corresponding Ruby constant is not defined.

Your platform documentations (e.g. man open(2)) may describe more detailed information.

File::Constants Reference

File::Stat

Objects of class File::Stat encapsulate common status information for File objects. The information is recorded at the moment the File::Stat object is created; changes made to the file after that point will not be reflected. File::Stat objects are returned by IO#stat, File::stat, File#lstat, and File::lstat. Many of these methods return platform-specific values, and not all values are meaningful on all systems. See also Kernel#test.

File::Stat Reference

FileTest

FileTest implements file test operations similar to those used in File::Stat. It exists as a standalone module, and its methods are also insinuated into the File class. (Note that this is not done by inclusion: the interpreter cheats).

FileTest Reference

Pathname

Part of standard library. You need to require 'pathname' before using.

Pathname represents the name of a file or directory on the filesystem, but not the file itself.

The pathname depends on the Operating System: Unix, Windows, etc. This library works with pathnames of local OS, however non-Unix pathnames are supported experimentally.

A Pathname can be relative or absolute. It’s not until you try to reference the file that it even matters whether the file exists or not.

Pathname is immutable. It has no method for destructive update.

The goal of this class is to manipulate file path information in a neater way than standard Ruby provides. The examples below demonstrate the difference.

All functionality from File, FileTest, and some from Dir and FileUtils is included, in an unsurprising way. It is essentially a facade for all of these, and more.

require 'pathname'
pn = Pathname.new("/usr/bin/ruby")
size = pn.size              # 27662
isdir = pn.directory?       # false
dir  = pn.dirname           # Pathname:/usr/bin
base = pn.basename          # Pathname:ruby
dir, base = pn.split        # [Pathname:/usr/bin, Pathname:ruby]
data = pn.read
pn.open { |f| _ }
pn.each_line { |line| _ }

Pathname Reference

Tempfile

Part of standard library. You need to require 'tempfile' before using.

A utility class for managing temporary files. When you create a Tempfile object, it will create a temporary file with a unique filename. A Tempfile objects behaves just like a File object, and you can perform all the usual file operations on it: reading data, writing data, changing its permissions, etc. So although this class does not explicitly document all instance methods supported by File, you can in fact call any File instance method on a Tempfile object.

require 'tempfile'

file = Tempfile.new('foo')
file.path      # => A unique filename in the OS's temp directory,
               #    e.g.: "/tmp/foo.24722.0"
               #    This filename contains 'foo' in its basename.
file.write("hello world")
file.rewind
file.read      # => "hello world"
file.close
file.unlink    # deletes the temp file

Tempfile Reference

FileUtils

Part of standard library. You need to require 'fileutils' before using.

Namespace for several file utility methods for copying, moving, removing, etc.

require 'fileutils'

FileUtils.cd(dir, options)
FileUtils.cd(dir, options) {|dir| block }
FileUtils.pwd()
FileUtils.mkdir(dir, options)
FileUtils.mkdir(list, options)
FileUtils.mkdir_p(dir, options)
FileUtils.mkdir_p(list, options)
FileUtils.rmdir(dir, options)
FileUtils.rmdir(list, options)
FileUtils.ln(target, link, options)
FileUtils.ln(targets, dir, options)
FileUtils.ln_s(target, link, options)
FileUtils.ln_s(targets, dir, options)
FileUtils.ln_sf(target, link, options)
FileUtils.cp(src, dest, options)
FileUtils.cp(list, dir, options)
FileUtils.cp_r(src, dest, options)
FileUtils.cp_r(list, dir, options)
FileUtils.mv(src, dest, options)
FileUtils.mv(list, dir, options)
FileUtils.rm(list, options)
FileUtils.rm_r(list, options)
FileUtils.rm_rf(list, options)
FileUtils.install(src, dest, options)
FileUtils.chmod(mode, list, options)
FileUtils.chmod_R(mode, list, options)
FileUtils.chown(user, group, list, options)
FileUtils.chown_R(user, group, list, options)
FileUtils.touch(list, options)

The options parameter is a hash of options, taken from the list :force, :noop, :preserve, and :verbose. :noop means that no changes are made. The other three are obvious. Each method documents the options that it honours.

All methods that have the concept of a “source” file or directory can take either one file or a list of files in that argument. See the method documentation for examples.

There are some low level methods, which do not accept any option:

FileUtils.copy_entry(src, dest, preserve = false, dereference_root = false, remove_destination = false)
FileUtils.copy_file(src, dest, preserve = false, dereference = true)
FileUtils.copy_stream(srcstream, deststream)
FileUtils.remove_entry(path, force = false)
FileUtils.remove_entry_secure(path, force = false)
FileUtils.remove_file(path, force = false)
FileUtils.compare_file(path_a, path_b)
FileUtils.compare_stream(stream_a, stream_b)
FileUtils.uptodate?(file, cmp_list)

FileUtils Reference

Find

Part of standard library. You need to require 'find' before using.

The Find module supports the top-down traversal of a set of file paths.

For example, to total the size of all files under your home directory, ignoring anything in a “dot” directory (e.g. $HOME/.ssh):

require 'find'

total_size = 0

Find.find(ENV["HOME"]) do |path|
  if FileTest.directory?(path)
    if File.basename(path)[0] == ?.
      Find.prune       # Don't look any further into this directory.
    else
      next
    end
  else
    total_size += FileTest.size(path)
  end
end

Find Reference