docs/expressions/string.html
string is zero or more characters written inside single or double quotes.
You can use quotes inside a string, as long as they don't match the quotes surrounding the string:
$var1 = "It's alright"
$var2 = "He is called 'Johnny'"
$var3 = 'He is called "Johnny"'
single quotes allow you to use the syntax of expressions within them.
The @ sign must be placed before the expressions.
item(title = 'windows dir path: @sys.dir')
double quotes allow you to use the Escape Character inside them only.
The backslash (\) escape character turns special characters into characters.
The sequence \" inserts a double quote in a string:
$var1 = "hello\"world"
// result: hello"world
The complete set of escape sequences is as follows:
| ' | Single quote | | " | Double quote | | \ | Backslash | | \0 | Null | | \a | Alert | | \b | Backspace | | \f | Form Feed | | \n | New Line | | \r | Carriage Return | | \t | Horizontal Tab | | \v | Vertical Tab | | \uxxxx | Unicode escape sequence (UTF-16) \uHHHH (range: 0000 - FFFF) | | \xnnnn | Unicode escape sequence for character with hex value nnnn (variable length version of \uxxxx) | | \Uxxxxxxxx | Unicode escape sequence (UTF-32) \U00HHHHHH (range: 000000 - 10FFFF) |