Pulled from https://www.gnu.org/software/bash/manual/bashref.html#ANSI_002dC-Quoting
As a side note there is a lot of good bash info out here. https://www.gnu.org/software/bash/manual/bashref.html
188.8.131.52 ANSI-C Quoting
Words of the form
$'string' are treated specially. The
word expands to string, with backslash-escaped characters replaced
as specified by the ANSI C standard. Backslash escape sequences, if
present, are decoded as follows:
an escape character (not ANSI C)
echo Hello $'\t' World
Returns “Hello World” with a tab space between both words.
echo Hello $'\n' World
Returns Hello on one line and World on the second
echo "\"Hello World\""
Returns “Hello World” inside double quotes