Variable	Positional Parameters
$0	Parameter Number 0 (Name of Command or Function)
$1	Parameter Number 1 (from command line or function)
...	Parameter number N …
$9	Parameter Number 9 (from command line or function)
${10}	Parameter Number 10 (from command line or function)
...	Parameter number NN …
$#	Total number of command line or function parameters
$*	All parameters as a single string
$@	All parameters, such as multiple protected strings
Variable	Miscellania
$$	PID number of current process (from script itself)
$!	PID number of last background job
$_	Last argument of last command executed
$?	Return code from last command executed