Today to see Bash4.0 reference documentation, a little personal insights bash in single and double quotes
apostrophe
Single quotes is what you enter what is displayed, including the use of $ variables will press to call you enter the content to be displayed, but can not go to nest single quotes, double quotes will only use nested output separately, also use the escape character not work
example:
With echo output variables
Single quotes nested with echo output
Double quotes
Double and single quotes, like, what input display, but will retain the shell extension, you can use the $, \, special characters and can be nested single quotes
bin examples:
With echo output variables
Single quotes nested with echo output
\ Explain echo output
