From The Free On-line Dictionary of Computing (19 January 2023):
dollar
$
$
<character> "$", numeric character reference: "$", Common
names: ITU-T: dollar sign. Rare: currency symbol; buck; cash;
string; escape (when used as the echo of ASCII ESC); ding;
cache; INTERCAL: big money.
Well-known uses of the dollar symbol in computing include as a
prefix on the names of string variables in BASIC, shell
and related languages like Perl. In shell languages it is also
used in positional parameters so "$1" is the first parameter to
a shell script, "$2" the second, etc. In a regular expression,
$ matches the end of the string.
(2015-01-24)