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

String Utilities