Class: Dir

Changes the current working directory.

With argument new_dirpath and no block, changes to the given dirpath:

Dir.pwd         # => "/example"
Dir.chdir('..') # => 0
Dir.pwd         # => "/"

With no argument and no block:

• Changes to the value of environment variable HOME if defined.

• Otherwise changes to the value of environment variable LOGDIR if defined.

• Otherwise makes no change.

With argument new_dirpath and a block, temporarily changes the working directory:

• Calls the block with the argument.

• Changes to the given directory.

• Executes the block (yielding the new path).

• Restores the previous working directory.

• Returns the block’s return value.

Example:

Dir.chdir('/var/spool/mail')
Dir.pwd   # => "/var/spool/mail"
Dir.chdir('/tmp') do
  Dir.pwd # => "/tmp"
end
Dir.pwd   # => "/var/spool/mail"

With no argument and a block, calls the block with the current working directory (string) and returns the block’s return value.

Calls to Dir.chdir with blocks may be nested:

Dir.chdir('/var/spool/mail')
Dir.pwd     # => "/var/spool/mail"
Dir.chdir('/tmp') do
  Dir.pwd   # => "/tmp"
  Dir.chdir('/usr') do
    Dir.pwd # => "/usr"
  end
  Dir.pwd   # => "/tmp"
end
Dir.pwd     # => "/var/spool/mail"

In a multi-threaded program an error is raised if a thread attempts to open a chdir block while another thread has one open, or a call to chdir without a block occurs inside a block passed to chdir (even in the same thread).

Raises an exception if the target directory does not exist.

Returns an array of the entry names in the directory at dirpath except for '.' and '..'; sets the given encoding onto each returned entry name:

Dir.children('/example') # => ["config.h", "lib", "main.rb"]
Dir.children('/example').first.encoding
# => #<Encoding:UTF-8>
Dir.children('/example', encoding: 'US-ASCII').first.encoding
# => #<Encoding:US-ASCII>

See {String Encoding}.

Raises an exception if the directory does not exist.

Changes the root directory of the calling process to that specified in dirpath. The new root directory is used for pathnames beginning with '/'. The root directory is inherited by all children of the calling process.

Only a privileged process may call chroot.

See Linux chroot.

Alias for .rmdir.

Like .foreach, except that entries '.' and '..' are not included.

Returns whether dirpath specifies an empty directory:

dirpath = '/tmp/foo'
Dir.mkdir(dirpath)
Dir.empty?(dirpath)            # => true
Dir.empty?('/example')         # => false
Dir.empty?('/example/main.rb') # => false

Raises an exception if dirpath does not specify a directory or file in the underlying file system.

Returns an array of the entry names in the directory at dirpath; sets the given encoding onto each returned entry name:

Dir.entries('/example') # => ["config.h", "lib", "main.rb", "..", "."]
Dir.entries('/example').first.encoding
# => #<Encoding:UTF-8>
Dir.entries('/example', encoding: 'US-ASCII').first.encoding
# => #<Encoding:US-ASCII>

See {String Encoding}.

Raises an exception if the directory does not exist.

Returns whether dirpath is a directory in the underlying file system:

Dir.exist?('/example')         # => true
Dir.exist?('/nosuch')          # => false
Dir.exist?('/example/main.rb') # => false

Same as File.directory?.

Changes the current working directory to the directory specified by the integer file descriptor fd.

When passing a file descriptor over a UNIX socket or to a child process, using fchdir instead of .chdir avoids the time-of-check to time-of-use vulnerability

With no block, changes to the directory given by fd:

Dir.chdir('/var/spool/mail')
Dir.pwd # => "/var/spool/mail"
dir  = Dir.new('/usr')
fd = dir.fileno
Dir.fchdir(fd)
Dir.pwd # => "/usr"

With a block, temporarily changes the working directory:

• Calls the block with the argument.

• Changes to the given directory.

• Executes the block (yields no args).

• Restores the previous working directory.

• Returns the block’s return value.

Example:

Dir.chdir('/var/spool/mail')
Dir.pwd # => "/var/spool/mail"
dir  = Dir.new('/tmp')
fd = dir.fileno
Dir.fchdir(fd) do
  Dir.pwd # => "/tmp"
end
Dir.pwd # => "/var/spool/mail"

This method uses the fchdir() function defined by POSIX 2008; the method is not implemented on non-POSIX platforms (raises ::NotImplementedError).

Raises an exception if the file descriptor is not valid.

In a multi-threaded program an error is raised if a thread attempts to open a .chdir block while another thread has one open, or a call to .chdir without a block occurs inside a block passed to .chdir (even in the same thread).

Returns a new Dir object representing the directory specified by the given integer directory file descriptor fd:

d0 = Dir.new('..')
d1 = Dir.for_fd(d0.fileno)

Note that the returned d1 does not have an associated path:

d0.path # => '..'
d1.path # => nil

This method uses the fdopendir() function defined by POSIX 2008; the method is not implemented on non-POSIX platforms (raises ::NotImplementedError).

Calls the block with each entry name in the directory at dirpath; sets the given encoding onto each passed entry_name:

Dir.foreach('/example') {|entry_name| p entry_name }

Output:

"config.h"
"lib"
"main.rb"
".."
"."

::Encoding:

Dir.foreach('/example') {|entry_name| p entry_name.encoding; break }
Dir.foreach('/example', encoding: 'US-ASCII') {|entry_name| p entry_name.encoding; break }

Output:

#<Encoding:UTF-8>
#<Encoding:US-ASCII>

See {String Encoding}.

Returns an enumerator if no block is given.

Alias for .pwd.

Forms an array entry_names of the entry names selected by the arguments.

Argument patterns is a string pattern or an array of string patterns; note that these are not regexps; see below.

Notes for the following examples:

• '*' is the pattern that matches any entry name except those that begin with '.'.

• We use method Array#take to shorten returned arrays that otherwise would be very large.

With no block, returns array entry_names; example (using the simple file tree):

Dir.glob('*') # => ["config.h", "lib", "main.rb"]

With a block, calls the block with each of the entry_names and returns nil:

Dir.glob('*') {|entry_name| puts entry_name } # => nil

Output:

config.h
lib
main.rb

If optional keyword argument flags is given, the value modifies the matching; see below.

If optional keyword argument base is given, its value specifies the base directory. Each pattern string specifies entries relative to the base directory; the default is '.'. The base directory is not prepended to the entry names in the result:

Dir.glob(pattern, base: 'lib').take(5)
# => ["abbrev.gemspec", "abbrev.rb", "base64.gemspec", "base64.rb", "benchmark.gemspec"]
Dir.glob(pattern, base: 'lib/irb').take(5)
# => ["cmd", "color.rb", "color_printer.rb", "completion.rb", "context.rb"]

If optional keyword sort is given, its value specifies whether the array is to be sorted; the default is true. Passing value false with that keyword disables sorting (though the underlying file system may already have sorted the array).

Patterns

Each pattern string is expanded according to certain metacharacters; examples below use the Ruby file tree:

• '*': Matches any substring in an entry name, similar in meaning to regexp /.*/mx; may be restricted by other values in the pattern strings:

  • '*' matches all entry names:

    Dir.glob('*').take(3)  # => ["BSDL", "CONTRIBUTING.md", "COPYING"]

  • 'c*' matches entry names beginning with 'c':

    Dir.glob('c*').take(3) # => ["CONTRIBUTING.md", "COPYING", "COPYING.ja"]

  • '*c' matches entry names ending with 'c':

    Dir.glob('*c').take(3) # => ["addr2line.c", "array.c", "ast.c"]

  • '*c*' matches entry names that contain 'c', even at the beginning or end:

    Dir.glob('*c*').take(3) # => ["CONTRIBUTING.md", "COPYING", "COPYING.ja"]

  Does not match Unix-like hidden entry names (“dot files”). To include those in the matched entry names, use flag IO::FNM_DOTMATCH or something like '{*,.*}'.

• '**': Matches entry names recursively if followed by the slash character '/':

  Dir.glob('**/').take(3) # => ["basictest/", "benchmark/", "benchmark/gc/"]

  If the string pattern contains other characters or is not followed by a slash character, it is equivalent to '*'.

• '?' Matches any single character; similar in meaning to regexp /./:

  Dir.glob('io.?') # => ["io.c"]

• '[set]': Matches any one character in the string set; behaves like a Regexp character class, including set negation ('[^a-z]'):

  Dir.glob('*.[a-z][a-z]').take(3)
  # => ["CONTRIBUTING.md", "COPYING.ja", "KNOWNBUGS.rb"]

• '{abc,xyz}': Matches either string abc or string xyz; behaves like Regexp alternation:

  Dir.glob('{LEGAL,BSDL}') # => ["LEGAL", "BSDL"]

  More than two alternatives may be given.

• \: Escapes the following metacharacter.

  Note that on Windows, the backslash character may not be used in a string pattern: Dir['c:\foo*'] will not work, use Dir['c:/foo*'] instead.

More examples (using the simple file tree):

# We're in the example directory.
File.basename(Dir.pwd) # => "example"
Dir.glob('config.?')              # => ["config.h"]
Dir.glob('*.[a-z][a-z]')          # => ["main.rb"]
Dir.glob('*.[^r]*')               # => ["config.h"]
Dir.glob('*.{rb,h}')              # => ["main.rb", "config.h"]
Dir.glob('*')                     # => ["config.h", "lib", "main.rb"]
Dir.glob('*', File::FNM_DOTMATCH) # => [".", "config.h", "lib", "main.rb"]
Dir.glob(["*.rb", "*.h"])         # => ["main.rb", "config.h"]

Dir.glob('**/*.rb')
#=> ["lib/song/karaoke.rb", "lib/song.rb", "main.rb"]

Dir.glob('**/*.rb', base: 'lib')  #   => ["song/karaoke.rb", "song.rb"]

Dir.glob('**/lib')                # => ["lib"]

Dir.glob('**/lib/**/*.rb')        # => ["lib/song/karaoke.rb", "lib/song.rb"]

Dir.glob('**/lib/*.rb')           # => ["lib/song.rb"]

Flags

If optional keyword argument flags is given (the default is zero – no flags), its value should be the bitwise OR of one or more of the constants defined in module ::File::Constants.

Example:

flags = File::FNM_EXTGLOB | File::FNM_DOTMATCH

Specifying flags can extend, restrict, or otherwise modify the matching.

The flags for this method (other constants in ::File::Constants do not apply):

• File::FNM_DOTMATCH: specifies that entry names beginning with '.' should be considered for matching:

  Dir.glob('*').take(5)
  # => ["BSDL", "CONTRIBUTING.md", "COPYING", "COPYING.ja", "GPL"]
  Dir.glob('*', flags: File::FNM_DOTMATCH).take(5)
  # => [".", ".appveyor.yml", ".cirrus.yml", ".dir-locals.el", ".document"]

• File::FNM_EXTGLOB: enables the pattern extension '{a,b}', which matches pattern a and pattern b; behaves like a regexp union (e.g., '(?:a|b)'):

  pattern = '{LEGAL,BSDL}'
  Dir.glob(pattern)      # => ["LEGAL", "BSDL"]

• File::FNM_NOESCAPE: specifies that escaping with the backslash character '\' is disabled; the character is not an escape character.

• File::FNM_PATHNAME: specifies that metacharacters '*' and '?' do not match directory separators.

• File::FNM_SHORTNAME: specifies that patterns may match short names if they exist; Windows only.

Returns the home directory path of the user specified with user_name if it is not nil, or the current login user:

Dir.home         # => "/home/me"
Dir.home('root') # => "/root"

Raises ArgumentError if user_name is not a user name.

Creates a directory in the underlying file system at dirpath with the given permissions; returns zero:

Dir.mkdir('foo')
File.stat(Dir.new('foo')).mode.to_s(8)[1..4] # => "0755"
Dir.mkdir('bar', 0644)
File.stat(Dir.new('bar')).mode.to_s(8)[1..4] # => "0644"

See {File Permissions}. Note that argument permissions is ignored on Windows.

Creates a new Dir object dir for the directory at dirpath.

With no block, the method equivalent to .new(dirpath, encoding):

Dir.open('.') # => #<Dir:.>

With a block given, the block is called with the created dir; on block exit dir is closed and the block’s value is returned:

Dir.open('.') {|dir| dir.inspect } # => "#<Dir:.>"

The value given with optional keyword argument encoding specifies the encoding for the directory entry names; if nil (the default), the file system’s encoding is used:

Dir.open('.').read.encoding                       # => #<Encoding:UTF-8>
Dir.open('.', encoding: 'US-ASCII').read.encoding # => #<Encoding:US-ASCII>

Returns the path to the current working directory:

Dir.chdir("/tmp") # => 0
Dir.pwd           # => "/tmp"

Removes the directory at dirpath from the underlying file system:

Dir.rmdir('foo') # => 0

Raises an exception if the directory is not empty.

Alias for .rmdir.

Sets the position in self and returns position. The value of position should have been returned from an earlier call to #tell; if not, the return values from subsequent calls to #read are unspecified.

See Dir As Stream-Like.

Examples:

dir = Dir.new('example')
dir.pos      # => 0
dir.pos = 3  # => 3
dir.pos      # => 3
dir.pos = 30 # => 30
dir.pos      # => 5

Alias for #pos.

Returns an array of the entry names in self except for '.' and '..':

dir = Dir.new('/example')
dir.children # => ["config.h", "lib", "main.rb"]

Closes the stream in self, if it is open, and returns nil; ignored if self is already closed:

dir = Dir.new('example')
dir.read     # => "."
dir.close     # => nil
dir.close     # => nil
dir.read # Raises IOError.

Calls the block with each entry name in self:

Dir.new('example').each {|entry_name| p entry_name }

Output:

"."
".."
"config.h"
"lib"
"main.rb"

With no block given, returns an ::Enumerator.

Calls the block with each entry name in self except '.' and '..':

dir = Dir.new('/example')
dir.each_child {|entry_name| p entry_name }

Output:

"config.h"
"lib"
"main.rb"

If no block is given, returns an enumerator.

Returns the file descriptor used in dir.

d = Dir.new('..')
d.fileno # => 8

This method uses the dirfd() function defined by POSIX 2008; the method is not implemented on non-POSIX platforms (raises ::NotImplementedError).

Returns a string description of self:

Dir.new('example').inspect # => "#<Dir:example>"

Returns the dirpath string that was used to create self (or nil if created by method .for_fd):

Dir.new('example').path # => "example"

Reads and returns the next entry name from self; returns nil if at end-of-stream; see Dir As Stream-Like:

dir = Dir.new('example')
dir.read # => "."
dir.read # => ".."
dir.read # => "config.h"

Sets the position in self to zero; see Dir As Stream-Like:

dir = Dir.new('example')
dir.read    # => "."
dir.read    # => ".."
dir.pos     # => 2
dir.rewind  # => #<Dir:example>
dir.pos     # => 0

Sets the position in self and returns self. The value of position should have been returned from an earlier call to #tell; if not, the return values from subsequent calls to #read are unspecified.

See Dir As Stream-Like.

Examples:

dir = Dir.new('example')
dir.pos      # => 0
dir.seek(3)  # => #<Dir:example>
dir.pos      # => 3
dir.seek(30) # => #<Dir:example>
dir.pos      # => 5

Alias for #path.