The Backslash Character and Special Expressions (GNU Grep 3.7)

From Get docs
Grep/docs/latest/The-Backslash-Character-and-Special-Expressions

3.3 The Backslash Character and Special Expressions

The ‘\’ character followed by a special character is a regular expression that matches the special character. The ‘\’ character, when followed by certain ordinary characters, takes a special meaning:

\b
Match the empty string at the edge of a word.
\B
Match the empty string provided it’s not at the edge of a word.
\<
Match the empty string at the beginning of a word.
\>
Match the empty string at the end of a word.
\w
Match word constituent, it is a synonym for ‘[_[:alnum:]]’.
\W
Match non-word constituent, it is a synonym for ‘[^_[:alnum:]]’.
\s
Match whitespace, it is a synonym for ‘Grep/docs/latest/:space:’.
\S
Match non-whitespace, it is a synonym for ‘[^[:space:]]’.

For example, ‘\brat\b’ matches the separate word ‘rat’, ‘\Brat\B’ matches ‘crate’ but not ‘furry rat’.