Now that we’ve seen how many ways the shell can perform expansions, it’s time to learn how we can control it. For example, take this:
echo this is a testthis is a test
echo The total is $100.00The total is 00.00
In the first example, word splitting by the shell removed extra whitespace from the
echo command’s list of arguments. In the second example, parameter expansion substituted an empty string for the value of
$1 because it was an undefined variable. The shell provides a mechanism called quoting to selectively suppress unwanted expansions.
The first type of quoting we will look at is double quotes. If you place text inside double quotes, all the special characters used by the shell ...