class File

Constants

PTOOLS_VERSION

The version of the ptools library.

Public Class Methods

binary?(file) click to toggle source

Returns whether or not file is a binary non-image file, i.e. executable, shared object, etc.

Internally this method simply looks for a double null sequence. This will work for the vast majority of cases, but it is not guaranteed to be absolutely accurate.

Example:

File.binary?('somefile.exe') # => true
File.binary?('somefile.txt') # => false

# File lib/ptools.rb, line 70
def self.binary?(file)
  return false if File.stat(file).zero?
  return false if image?(file)
  return false if check_bom?(file)

  bytes = File.stat(file).blksize
  bytes = 4096 if bytes > 4096
  (File.read(file, bytes) || '').include?("\u0000\u0000")
end
bmp?(file) click to toggle source

Is the file a bitmap file?

# File lib/ptools.rb, line 424
def self.bmp?(file)
  data = File.read(file, 6, nil, :encoding => 'binary')
  data[0,2] == 'BM' && File.size(file) == data[2,4].unpack('i').first
end
gif?(file) click to toggle source

Is the file a gif?

# File lib/ptools.rb, line 443
def self.gif?(file)
  %w[GIF89a GIF97a].include?(File.read(file, 6))
end
head(filename, num_lines = 10) { |line| ... } click to toggle source

In block form, yields the first num_lines from filename. In non-block form, returns an Array of num_lines

Examples:

# Return an array
File.head('somefile.txt') # => ['This is line1', 'This is line2', ...]

# Use a block
File.head('somefile.txt'){ |line| puts line }

# File lib/ptools.rb, line 203
def self.head(filename, num_lines = 10)
  a = []

  File.foreach(filename) do |line|
    break if num_lines <= 0

    num_lines -= 1
    if block_given?
      yield line
    else
      a << line
    end
  end

  a.empty? ? nil : a # Return nil in block form
end
ico?(file) click to toggle source

Is the file an ico file?

# File lib/ptools.rb, line 466
def self.ico?(file)
  ["\000\000\001\000", "\000\000\002\000"].include?(File.read(file, 4, nil, :encoding => 'binary'))
end
image?(file, check_file_extension: true) click to toggle source

Returns whether or not the file is an image. Only JPEG, PNG, BMP, GIF, and ICO are checked against.

This reads and checks the first few bytes of the file. For a version that is more robust, but which depends on a 3rd party C library (and is difficult to build on MS Windows), see the ‘filemagic’ library.

By default the filename extension is also checked. You can disable this by passing false as the second argument, in which case only the contents are checked.

Examples:

File.image?('somefile.jpg') # => true
File.image?('somefile.txt') # => false

# File lib/ptools.rb, line 50
def self.image?(file, check_file_extension: true)
  bool = bmp?(file) || jpg?(file) || png?(file) || gif?(file) || tiff?(file) || ico?(file)

  bool &&= IMAGE_EXT.include?(File.extname(file).downcase) if check_file_extension

  bool
end
jpg?(file) click to toggle source

Is the file a jpeg file?

# File lib/ptools.rb, line 431
def self.jpg?(file)
  File.read(file, 10, nil, :encoding => 'binary') == "\377\330\377\340\000\020JFIF".force_encoding(Encoding::BINARY)
end
nl_convert(old_file, new_file = old_file, platform = 'local') click to toggle source

Converts a text file from one OS platform format to another, ala ‘dos2unix’. The possible values for platform include:

  • MS Windows -> dos, windows, win32, mswin

  • Unix/BSD -> unix, linux, bsd, osx, darwin, sunos, solaris

  • Mac -> mac, macintosh, apple

You may also specify ‘local’, in which case your CONFIG value will be used. This is the default.

Note that this method is only valid for an ftype of “file”. Otherwise a TypeError will be raised. If an invalid format value is received, an ArgumentError is raised.

# File lib/ptools.rb, line 283
def self.nl_convert(old_file, new_file = old_file, platform = 'local')
  raise ArgumentError, 'Only valid for plain text files' unless File::Stat.new(old_file).file?

  format = nl_for_platform(platform)

  if old_file == new_file
    require 'tempfile'
    temp_name = Time.new.strftime('%Y%m%d%H%M%S')
    nf = Tempfile.new("ruby_temp_#{temp_name}")
  else
    nf = File.new(new_file, 'w')
  end

  begin
    nf.open if old_file == new_file
    File.foreach(old_file) do |line|
      line.chomp!
      nf.print("#{line}#{format}")
    end
  ensure
    nf.close if nf && !nf.closed?
    if old_file == new_file
      require 'fileutils'
      File.delete(old_file)
      FileUtils.mv(nf.path, old_file)
    end
  end

  self
end
nl_for_platform(platform) click to toggle source

Returns the newline characters for the given platform.

# File lib/ptools.rb, line 407
def self.nl_for_platform(platform)
  platform = RbConfig::CONFIG['host_os'] if platform == 'local'

  case platform
    when /dos|windows|win32|mswin|mingw/i
      "\cM\cJ"
    when /unix|linux|bsd|cygwin|osx|darwin|solaris|sunos/i
      "\cJ"
    when /mac|apple|macintosh/i
      "\cM"
    else
      raise ArgumentError, 'Invalid platform string'
  end
end
png?(file) click to toggle source

Is the file a png file?

# File lib/ptools.rb, line 437
def self.png?(file)
  File.read(file, 4, nil, :encoding => 'binary') == "\211PNG".force_encoding(Encoding::BINARY)
end
sparse?(file) click to toggle source

Returns whether or not file is a sparse file.

A sparse file is a any file where its size is greater than the number of 512k blocks it consumes, i.e. its apparent and actual file size is not the same.

See en.wikipedia.org/wiki/Sparse_file for more information.

# File lib/ptools.rb, line 383
def self.sparse?(file)
  stats = File.stat(file)
  stats.size > stats.blocks * 512
end
tail(filename, num_lines = 10, &block) click to toggle source

In block form, yields the last num_lines of file filename. In non-block form, it returns the lines as an array.

Example:

File.tail('somefile.txt') # => ['This is line7', 'This is line8', ...]

If you’re looking for tail -f functionality, please use the file-tail gem instead.

# File lib/ptools.rb, line 234
def self.tail(filename, num_lines = 10, &block)
  tail_size = 2**16 # 64k chunks

  # MS Windows gets unhappy if you try to seek backwards past the
  # end of the file, so we have some extra checks here and later.
  file_size  = File.size(filename)
  read_bytes = file_size % tail_size
  read_bytes = tail_size if read_bytes == 0

  line_sep = File::ALT_SEPARATOR ? "\r\n" : "\n"

  buf = ''

  # Open in binary mode to ensure line endings aren't converted.
  File.open(filename, 'rb') do |fh|
    position = file_size - read_bytes # Set the starting read position

    # Loop until we have the lines or run out of file
    while buf.scan(line_sep).size <= num_lines and position >= 0
      fh.seek(position, IO::SEEK_SET)
      buf = fh.read(read_bytes) + buf
      read_bytes = tail_size
      position -= read_bytes
    end
  end

  lines = buf.split(line_sep).pop(num_lines)

  if block_given?
    lines.each(&block)
  else
    lines
  end
end
tiff?(file) click to toggle source

Is the file a tiff?

# File lib/ptools.rb, line 449
def self.tiff?(file)
  return false if File.size(file) < 12

  bytes = File.read(file, 4)

  # II is Intel, MM is Motorola
  return false if bytes[0..1] != 'II' && bytes[0..1] != 'MM'

  return false if bytes[0..1] == 'II' && bytes[2..3].ord != 42

  return false if bytes[0..1] == 'MM' && bytes[2..3].reverse.ord != 42

  true
end
touch(filename) click to toggle source

Changes the access and modification time if present, or creates a 0 byte file filename if it doesn’t already exist.

# File lib/ptools.rb, line 317
def self.touch(filename)
  if File.exist?(filename)
    time = Time.now
    File.utime(time, time, filename)
  else
    File.open(filename, 'w'){}
  end
  self
end
wc(filename, option = 'all') click to toggle source

With no arguments, returns a four element array consisting of the number of bytes, characters, words and lines in filename, respectively.

Valid options are ‘bytes’, ‘characters’ (or just ‘chars’), ‘words’ and ‘lines’.

# File lib/ptools.rb, line 333
def self.wc(filename, option = 'all')
  option.downcase!
  valid = %w[all bytes characters chars lines words]

  raise ArgumentError, "Invalid option: '#{option}'" unless valid.include?(option)

  n = 0

  if option == 'lines'
    File.foreach(filename){ n += 1 }
    n
  elsif option == 'bytes'
    File.open(filename) do |f|
      f.each_byte{ n += 1 }
    end
    n
  elsif %w[characters chars].include?(option)
    File.open(filename) do |f|
      n += 1 while f.getc
    end
    n
  elsif option == 'words'
    File.foreach(filename) do |line|
      n += line.split.length
    end
    n
  else
    bytes, chars, lines, words = 0, 0, 0, 0
    File.foreach(filename) do |line|
      lines += 1
      words += line.split.length
      chars += line.chars.length
    end
    File.open(filename) do |f|
      bytes += 1 while f.getc
    end
    [bytes, chars, words, lines]
  end
end
whereis(program, path = ENV['PATH']) click to toggle source

Returns an array of each program within path, or nil if it cannot be found.

On Windows, it looks for executables ending with the suffixes defined in your PATHEXT environment variable, or ‘.exe’, ‘.bat’ and ‘.com’ if that isn’t defined, which you may optionally include in program.

Examples:

File.whereis('ruby') # => ['/usr/bin/ruby', '/usr/local/bin/ruby']
File.whereis('foo')  # => nil

# File lib/ptools.rb, line 146
def self.whereis(program, path = ENV['PATH'])
  raise ArgumentError, 'path cannot be empty' if path.nil? || path.empty?

  paths = []

  # Bail out early if an absolute path is provided.
  if program =~ /^\/|^[a-z]:[\\\/]/i
    program += WIN32EXTS if MSWINDOWS && File.extname(program).empty?
    program = program.tr(File::ALT_SEPARATOR, File::SEPARATOR) if MSWINDOWS
    found = Dir[program]
    if found[0] && File.executable?(found[0]) && !File.directory?(found[0])
      if File::ALT_SEPARATOR
        return found.map{ |f| f.tr(File::SEPARATOR, File::ALT_SEPARATOR) }
      else
        return found
      end
    else
      return nil
    end
  end

  # Iterate over each path glob the dir + program.
  path.split(File::PATH_SEPARATOR).each do |dir|
    next unless File.exist?(dir) # In case of bogus second argument

    file = File.join(dir, program)

    # Dir[] doesn't handle backslashes properly, so convert them. Also, if
    # the program name doesn't have an extension, try them all.
    if MSWINDOWS
      file = file.tr(File::ALT_SEPARATOR, File::SEPARATOR)
      file += WIN32EXTS if File.extname(program).empty?
    end

    found = Dir[file].first

    # Convert all forward slashes to backslashes if supported
    if found && File.executable?(found) && !File.directory?(found)
      found.tr!(File::SEPARATOR, File::ALT_SEPARATOR) if File::ALT_SEPARATOR
      paths << found
    end
  end

  paths.empty? ? nil : paths.uniq
end
which(program, path = ENV['PATH']) click to toggle source

Looks for the first occurrence of program within path.

On Windows, it looks for executables ending with the suffixes defined in your PATHEXT environment variable, or ‘.exe’, ‘.bat’ and ‘.com’ if that isn’t defined, which you may optionally include in program.

Returns nil if not found.

Examples:

File.which('ruby') # => '/usr/local/bin/ruby'
File.which('foo')  # => nil

# File lib/ptools.rb, line 93
def self.which(program, path = ENV['PATH'])
  raise ArgumentError, 'path cannot be empty' if path.nil? || path.empty?

  # Bail out early if an absolute path is provided.
  if program =~ /^\/|^[a-z]:[\\\/]/i
    program += WIN32EXTS if MSWINDOWS && File.extname(program).empty?
    found = Dir[program].first
    if found && File.executable?(found) && !File.directory?(found)
      return found
    else
      return nil
    end
  end

  # Iterate over each path glob the dir + program.
  path.split(File::PATH_SEPARATOR).each do |dir|
    dir = File.expand_path(dir)

    next unless File.exist?(dir) # In case of bogus second argument

    file = File.join(dir, program)

    # Dir[] doesn't handle backslashes properly, so convert them. Also, if
    # the program name doesn't have an extension, try them all.
    if MSWINDOWS
      file = file.tr(File::ALT_SEPARATOR, File::SEPARATOR)
      file += WIN32EXTS if File.extname(program).empty?
    end

    found = Dir[file].first

    # Convert all forward slashes to backslashes if supported
    if found && File.executable?(found) && !File.directory?(found)
      found.tr!(File::SEPARATOR, File::ALT_SEPARATOR) if File::ALT_SEPARATOR
      return found
    end
  end

  nil
end

Private Class Methods

check_bom?(file) click to toggle source

Returns whether or not the given text contains a BOM marker. If present, we can generally assume it’s a text file.

# File lib/ptools.rb, line 392
def self.check_bom?(file)
  text = File.read(file, 4).force_encoding('utf-8')

  bool = false
  bool = true if text[0, 3] == "\xEF\xBB\xBF"
  bool = true if text[0, 4] == "\x00\x00\xFE\xFF" || text[0, 4] == "\xFF\xFE\x00\x00"
  bool = true if text[0, 2] == "\xFF\xFE" || text[0, 2] == "\xFE\xFF"

  bool
end