Single/double quotation marks in linux shell

· Single quotation marks, as in the preceding example, will always get you exactly what's inside the quotation marks--any charactersthat might otherwise have special meaning to the shell (like the dollar sign or the backslash) are treated literally.

· Use double quotation marks when you want to assign a string that contains special characters the shell should act on.

· The backslash is used to escape (treat literally) a single character (such as $ or *) that might otherwise be treated as a special character by the shell.

Now let's look at some examples that show when to use each method of quoting.

howdy='Good Morning $USER !'
echo $howdy
Good Morning $USER !
howdy="Good Morning $USER !"
echo $howdyGood Morning hermie !