Escaping a String in Ruby

Best way to escape and unescape strings in Ruby?

Ruby 2.5 added String#undump as a complement to String#dump:

$ irb
irb(main):001:0> dumped_newline = "\n".dump
=> "\"\\n\""
irb(main):002:0> undumped_newline = dumped_newline.undump
=> "\n"

With it:

def escape(s)
  s.dump[1..-2]
end

def unescape(s)
  "\"#{s}\"".undump
end

$irb
irb(main):001:0> escape("\n \" \\")
=> "\\n \\\" \\\\"
irb(main):002:0> unescape("\\n \\\" \\\\")
=> "\n \" \\"

String literal without need to escape backslash

There is somewhat similar thing available in Ruby. E.g.

foo = %Q(The integer division operator in VisualBASIC is written "a \\ b" and #{'interpolation' + ' works'})

You can also interpolate strings in it. The only caveat is, you would still need to escape \ character.

HTH

How to escape strings for terminal in Ruby?

Shellwords should work for you :)

exec "/usr/bin/mplayer %s" % Shellwords.escape(song.file)

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In ruby 1.9.x, it looks like you have to require it first

require "shellwords"

But in ruby 2.0.x, I didn't have to explicitly require it.

escaping a string in Ruby

Don't use multiple methods - keep it simple.

Escape the #, the backslash, and the double-quote.

irb(main):001:0> foo = "`~!@\#$%^&*()_-+={}|[]\\:\";'<>?,./"
=> "`~!@\#$%^&*()_-+={}|[]\\:\";'<>?,./"

Or if you don't want to escape the # (the substitution character for variables in double-quoted strings), use and escape single quotes instead:

irb(main):002:0> foo = '`~!@#$%^&*()_-+={}|[]\\:";\'<>?,./'
=> "`~!@\#$%^&*()_-+={}|[]\\:\";'<>?,./"

%q is great for lots of other strings that don't contain every ascii punctuation character. :)

%q(text without parens)
%q{text without braces}
%Q[text without brackets with #{foo} substitution]

Edit: Evidently you can used balanced parens inside %q() successfully as well, but I would think that's slightly dangerous from a maintenance standpoint, as there's no semantics there to imply that you're always going to necessarily balance your parens in a string.

How do I escape #{ from string interpolation

I think the backslash-hash is just Ruby being helpful in some irb-only way.

>> a,b = 1,2        #=> [1, 2]
>> s = "#{a} \#{b}" #=> "1 \#{b}"
>> puts s           #=> 1 #{b}
>> s.size           #=> 6

So I think you already have the correct answer.

Removing backslash (escape character) from a string

When you write:

input = "{ \"foo\": \"bar\", \"num\": 3}"

The actual string stored in input is:

{ "foo": "bar", "num": 3}

The escape \" here is interpreted by Ruby parser, so that it can distinguish between the boundary of a string (the left most and the right most "), and a normal character " in a string (the escaped ones).

String#delete deletes a character set specified the first parameter, rather than a pattern. All characters that is in the first parameter will be removed. So by writing

input.delete('\\"')

You got a string with all \ and " removed from input, rather than a string with all \" sequence removed from input. This is wrong for your case. It may cause unexpected behavior some time later.

String#gsub, however, substitute a pattern (either regular expression or plain string).

input.gsub('\\"', '')

means find all \" (two characters in a sequence) and replace them with empty string. Since there isn't \ in input, nothing got replaced. What you need is actually:

input.gsub('"', '')

Is is possible to create a string in ruby that keeps escaping characters?

You can use the %q delimiter rather than ":

def user_data
     %q[#!/bin/bash
     sed -i -e '/<Name>loadbalanceServerIP<\/Name>/,/<Value>/s/<Value>[^<]*/<Value>1.1.1.1/' /home/wowza/conf/Server.xml]
end

How to print an escape character in Ruby?

Use String#inspect

puts word.inspect #=> "x\nz"

Or just p

p word #=> "x\nz"

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