Dollar sign in Linux Shell $

In Linux Shell, the dollar sign $ in linux often encounters a lot of dollar signs ($). Some symbols are easy to mix up. I will make a record of what they represent: www.2cto.com $0 shell command itself (including the full path) $1 to $9 indicates the shell parameters $ # number of parameters passed to the script $ * display all parameters passed to the script with a single string $ ID of the script running $! The ID of the last process running in the background is $ @ and $. $-Display the current options used by shell. $? Displays the execution status of the last command. 0 indicates no error. For example: www.2cto.com [root @ CentOS haha]/tmp] $. /test. sh p1 p2 $0 is {. /test. sh} $1 is {p1} $2 is {p2} $ * is {p1 p2} $ @ is {p1 p2} $ # is {2} $! Is {}$ $ is {25643 }$? Is {0}