Introduction
Installation
Other Implementations of Ruby
Interactive Console
Ruby in Twenty Minutes
Language Structure
Keywords
Literals
Comments
Variables and Constants
Assignment
Control Expressions
Pattern matching
Defining methods
Calling methods
Modules and Classes
Exceptions
Refinements
Precedence
Miscellaneous Syntax
File Structure
Globals
Metaprogramming and DSL
Built-in Classes
Language Core
Kernel
Object
Module and Class
Method and Proc
Binding
Value Types
true, false, nil
Comparable
Numbers
Symbol and String
Regexp
Range
Struct
Times and Dates
Enumerable
Array
Hash
Set
Matrix
Exception
Exception Classes
Warning
System Programming and CLI
Processes and Signals
IO Basics
Filesystem
Arguments and Environment
Concurrency and Parallelism
Interpreter Internals
RubyVM
Marshal
Standard Library
Design Patterns
forwardable
delegate
observer
singleton
Formats
csv
json
yaml
rexml: XML parser and generator
rss
zlib
Development and Debugging
benchmark
coverage
debug
fiddle: FFI wrapper
logger
pp: Debug Print
ripper: Parsing Ruby
tracer
String Utilities
erb: Ruby Templating
racc: Parser Generator
shellwords: Shell-aware string manipulation
strscan: Sequental String Scanner
did_you_mean: Typo suggestions
Networking and Web
cgi
ipaddr
net/ftp
net/http
net/imap
net/pop
net/smtp
openuri: Open Files and URLs
resolv: DNS Resolver
socket
webrick: Simple Web Server
uri
System Programming and CLI
etc: Access to Unix /etc
fcntl: POSIX file access constants
open3: Flexible child processes
optparse: CLI arguments parser
pty: Pseudo terminal
readline
syslog
win32ole
Cryptography and Encoding
base64
digest
openssl
Miscellaneous Libraries
Concurrency Utils
drb: Distributed Ruby
dbm, gdbm, sdbm
timeout
Other Libraries
Bundled Gems
Developing in Ruby
Libraries
Bundler dependency manager
Mastering IRB
Documenting Ruby Code
Testing Ruby Code
Code Style
Advanced Topics
Developing C Extensions
Security
DTrace
Implementing Signal.trap callbacks
Contributing To Ruby
Appendix A: Kernel methods list
Appendix B: Useful Links
Ruby
2.7
Reference
SAVE
UKRAINE
Language Core
This section describes language core objects.