Files and Directories in Ruby

Listing Directories

Using the Dir.entries method or the Dir, the foreach iterator is the most straightforward approach to enumerate the contents of a directory.

For example:

# Get the names of all files in the config/ directory
filenames = Dir.entries("config") # Get names as an array
Dir.foreach("config") {|filename| ... } # Iterate names

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The names provided by these methods, which on Unix-like platforms contain "." (the current directory) and ".." (the parent directory), are not guaranteed to be in any particular order—the Dir.[] operator may be used to get a list of files that match a specific pattern.

Testing Files

Several ways to get metadata on a named file or directory are defined by File. A large number of the techniques return low-level, OS-dependent data. Here, just the most lightweight and widely applicable options are shown. Use “ri” on the File and File::Stat classes for a comprehensive set of methods.

For example:

f = "/usr/bin/ruby" # A filename for the examples below

# File existence and types.

File.exist?(f) # Does the named file exist? Also: Does the file exist?
File.file?(f) # Is it an existing file?
File.directory?(f) # Or is it an existing directory?
File.symlink?(f) # Is it a symbolic link?

# File size methods. Use File.truncate to set file size.

File.size(f) # File size in bytes.
File.size?(f) # Size in bytes or nil if empty file.
File.zero?(f) # True if file is empty.

# File permissions. Use File.chmod to set permissions (system dependent).

File.readable?(f) # Can we read the file?
File.writable?(f) # Can we write the file? No "e" in "writable"
File.executable?(f) # Can we execute the file?
File.world_readable?(f) # Can everybody read it? Ruby 1.9.
File.world_writable?(f) # Can everybody write it? Ruby 1.9.

# File times/dates. Use File.utime to set the times.

File.mtime(f) # => Last modification time as a Time object
File.atime(f) # => Last access time as a Time object

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Using ftype, which produces a string naming the type, you may also determine the type of a filename (file, directory, symbolic link, etc.). Assuming that /usr/bin/ruby is a shortcut to /usr/bin/ruby1.9, here are some examples:

File.ftype("/usr/bin/ruby") # => "link"
File.ftype("/usr/bin/ruby1.9") # => "file"
File.ftype("/usr/lib/ruby") # => "directory"
File.ftype("/usr/bin/ruby3.0") # SystemCallError: No such file or directory

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Creating Files and Directories in Ruby

Below we have discusses how to create files and directories in ruby.

No unique methods exist for creating a file defined in the File class. Simply open it for writing, enter 0 or more bytes, and then shut it to create one. Open a file in append mode if you don't want to overwrite an already-existing one.

# Create (or overwrite) a file named "test"
File.open("test", "w") {}
# Create (but do not clobber) a file named "test"
File.open("test", "a") {}

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Use Dir.mkdir to create a new directory.

Dir.mkdir("temp") # Create a directory

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Renaming Files and Directories in Ruby

Below we have discussed how to rename files and directories in ruby.

Use File.rename to modify a file's name:

File.rename("test", "test.old") # Current name followed by new name

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To rename a directory, use.

require 'fileutils'
FileUtils.mv sourcedir, newdir

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Deleting Files and Directories in Ruby

Below we have discussed how to delete files and directories in ruby.

Use File.delete or unlink to remove a file or link.

File.delete("test2") # May also be called with multiple args
File.unlink("oldtest") # to delete multiple named files

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Use Dir.rmdir or one of its equivalents, Dir.delete or Dir.unlink, to remove a directory. Before being erased, the directory must be empty.

File.delete(*Dir["temp/*"]) # Delete all files in the directory
Dir.rmdir("temp") # Delete the directory

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Frequently Asked Questions

What in Ruby is a directory?

A place where files can be kept is in a directory. In Ruby, directories are managed by the FileUtils module and the Dir class, whereas the File class deals with files.

What in Ruby is a file?

A File is a class of IO objects that abstracts any file object accessible by the application. You may write (for example) File.exist?("foo") since File includes the module FileTest's class methods.

What occurs when a file is required in Ruby?

The need method in Ruby is used to load a different file and run all its instructions. This imports all of the file's class and method definitions.

How does Ruby generate directories?

The Dir. mkdir function in Ruby may be used to create new folders. This directory is created beneath the current path if a relative path is provided ( Dir. pwd ).

Which approach does Ruby use when writing to a file?

You can write material into a file using the syswrite technique. The file must be opened in write mode for this approach to work. In an existing file, the new material will replace the old content.

Conclusion

In this article, we have extensively discussed Files and Directories in ruby.

After reading about the files and directories in ruby, are you not feeling excited to read/explore more articles on the topic of DSA? Don't worry; Coding Ninjas has you covered. To learn, see Try Ruby, the History of Ruby and Constants in Ruby.

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