%Q (executes #{})

This is an alternative for double-quoted strings, when you have more quote
characters in a string.Instead of putting backslashes in front of them,
you can easily write:

>> %Q(Joe said: "Frank said: "#{what_frank_said}"")
=> "Joe said: "Frank said: "Hello!"""

The parenthesis “(…)” can be replaced with any other non-alphanumeric characters
and non-printing characters (pairs), so the following commands are equivalent:

>> %Q!Joe said: "Frank said: "#{what_frank_said}""!
>> %Q[Joe said: "Frank said: "#{what_frank_said}""]
>> %Q+Joe said: "Frank said: "#{what_frank_said}""+

You can use also:

>> %/Joe said: "Frank said: "#{what_frank_said}""/
=> "Joe said: "Frank said: "Hello!"""

%q

Used for single-quoted strings.The syntax is similar to %Q, but single-quoted
strings are not subject to expression substitution or escape sequences.

>> %q(Joe said: 'Frank said: '#{what_frank_said} ' ')
=> "Joe said: 'Frank said: '\#{what_frank_said} ' '"

%W (executes #{})

Used for double-quoted array elements.The syntax is similar to %Q

>> %W(#{foo} Bar Bar\ with\ space)
=> ["Foo", "Bar", "Bar with space"]

%w

Used for single-quoted array elements.The syntax is similar to %Q, but
single-quoted elements are not subject to expression substitution or escape
sequences.

>> %w(#{foo} Bar Bar\ with\ space)
=> ["\#{foo}", "Bar", "Bar with space"]

%x (executes #{})

Uses the ` method and returns the standard output of running the command in a
subshell. The syntax is similar to %Q.

>> %x(echo foo:#{foo})
=> "foo:Foo\n"

%r (executes #{})

Used for regular expressions.The syntax is similar to %Q.

>> %r(/home/#{foo})
=> "/\\/home\\/Foo/"

%s

Used for symbols. ItтАЩs not subject to expression substitution or escape sequences.

>> %s(foo)
=> :foo
>> %s(foo bar)
=> :"foo bar"
>> %s(#{foo} bar)
=> :"\#{foo} bar"

%i

Used for array of symbols. ItтАЩs not subject to expression substitution or escape sequences.

>> %i(foo bar)
=> [:foo, :bar]
>> %i(#{foo} bar)
=> [:"\#{foo}", :bar]

%I (executes #{})

Used for array of symbols.

>> %I(#{foo} bar)
=> [:Foo, :bar]

Feel free to add/correct this file at https://gist.github.com/sadfuzzy/f1b6cce96d1c5d422176