Linux Shell Scripting Cookbook - Third Edition

Matched string notation ()

The & symbol is the matched string. This value can be used in the replacement string:

    $ echo this is an example | sed 's/\w\+/[&]/g'
    [this] [is] [an] [example]

Here, the \w\+ regex matches every word. Then, we replace it with [&], which corresponds to the word that is matched.