class File

• File
• IO::FileDescriptor
• IO
• Reference
• Object

Overview

A File instance represents a file entry in the local file system and allows using it as an IO.

file = File.new("path/to/file")
content = file.gets_to_end
file.close

# Implicit close with `open`
content = File.open("path/to/file") do |file|
  file.gets_to_end
end

# Shortcut:
content = File.read("path/to/file")

Temporary Files

Every tempfile is operated as a File, including initializing, reading and writing.

tempfile = File.tempfile("foo")

File.size(tempfile.path)                   # => 6
File.info(tempfile.path).modification_time # => 2015-10-20 13:11:12 UTC
File.exists?(tempfile.path)                # => true
File.read_lines(tempfile.path)             # => ["foobar"]

Files created from tempfile are stored in a directory that handles temporary files (Dir.tempdir):

File.tempfile("foo").path # => "/tmp/foo.ulBCPS"

It is encouraged to delete a tempfile after using it, which ensures they are not left behind in your filesystem until garbage collected.

tempfile = File.tempfile("foo")
tempfile.delete

Included Modules

• Crystal::System::File

Defined in:

Class Method Summary

• .chown(path : String, owner : User? = nil, group : Group? = nil, follow_symlinks : Bool = false) : Nil

  Changes the owner of the specified file.

• .chown?(path : String, owner : User? = nil, group : Group? = nil, follow_symlinks : Bool = false) : Bool

  Same as chown() but instead returns a Bool indicating success.

Class Method Detail

File.chown("/foo/bar/baz.cr", "a_owner", "a_group")
File.chown("/foo/bar", group: "a_group")

File.chown("foo", group: "a_group")                        # changes foo's group to "a_group"
File.chown("baz", group: "a_group", follow_symlinks: true) # changes baz's group to "a_group"