What does $$,$#,$ in the "share" shell script mean?

Give you a full, you in the Linux environment to try to understand more:
The execution name of this program
$n the nth parameter value of this program, n=1..9
$* all parameters of this program, this option can have more than 9 parameters.
$# the number of parameters for this program
$$ the PID of this program (the current process ID number of the script run)
$! PID of the previous background instruction (process ID number of the last process running in the background)
$? Executes the return value of the previous instruction (displays the exit status of the last command. 0 means no error, any other value indicates an error)
$-shows the current options used by the shell, same as the SET command function
[email protected] is similar to $*, but can be used as an array

What does $$,$#,$ in the "share" shell script mean?