sed中将普通字符转义为元字符

sed and awk

Chapter 3
Understanding Regular Expression Syntax

3.2 a line-up of characters

In addition, sed uses the backslash to cause a group of ordinary characters to be interpreted as metacharacters, as shown in below:

\( \) \{ \} \n

The n in the "\n" construct represents a digit from 1 to 9

But in awk ,we use () to group regular expressions.