Special bash characters

Special bash character	Meaning
#	# is used to comment a single line in bash script
$$	$$ is used to reference process id of any command or bash script
$0	$0 is used to get the name of the command in a bash script.
$name	$name will print the value of variable “name” defined in the script.
$n	$n will print the value of nth argument provided to bash script (n ranges from 0 to 9) e.g. $1 will print first argument.
>	> is used to redirect output
>>	>> can be used to Append to file
<	< will redirect input
[ ]	[] are for matching any characters enclosed
( )	Execute in subshell
	Another powerful special bash character which is used to substitute output of enclosed command
" "	Partial quote (allows variable and command expansion)
' '	Full quote (no expansion)
\	Quote following character
|	Pipe output of one command to another most useful and immensely power bash character
&	& is used to run any process in the background.
;	;(semi colon ) is used to separate commands on same line
*	* is used to match any character(s) in filename
?	? is for matching single character in filename