There are some fancy build-in variables in bash that I picked up from others’ scripts. They start with a dollar sign. Guess I’ll take some notes. (mostly stole from SO)[https://stackoverflow.com/questions/5163144/what-are-the-special-dollar-sign-shell-variables]
$#number of arguments
$*return all the parameters, but answer on SO
$*except that when quoted the arguments are broken up properly if there are spaces in them.
$?was last command successful?
$0 $1 $2 ...positional arguments,
$#number of positional parameters ($0 excluded)
$-current options set for the shell
$$pid of the current shell
$_most recent parameter (probably rarely used)