[$] Shell script in a shell script

  shell script '$' symbol with a meaning different from its representation will be different

Special identifier	meaning
$0	The current name of the script file
$n	Arguments passed to the script or function. n is a number that represents the number of parameters. For example, the first parameter is $ 1, $ 2 is the second parameter
$#	The number of arguments passed to the script or function
$*	Passed to the script or function of all parameters
$@	Passed to the script or function of all parameters
$?	The exit status of the previous command
$$	Shell current process ID
$()	And `(backtick) command is used to replace the use of the same
${}	Reference variables divided border

Note: $ * and $ @ expressed passed to all parameters of the function or script, "included, are not to be double quotation marks (") "output of all parameters in the form of $ 1" "$ 2" ... "$ n" is. However, when they are in double quotes ( "") included, "$ *" resets all of the parameters as a whole, to "$ 1 $ 2 ... $ n" output in the form of all parameters; "separate $ @" will each parameter, All output parameters in the form of "$ 1" "$ 2" ... "$ n" of

#! /bin/bash
echo "file name $0"
echo "first param  $1"
echo "pid $$"
echo "total num of param $#"
echo "last status $?"
echo "$@"
echo "$*"

Execution ./1.sh hello mayuan

file name ./1.sh
first param  hello
pid 142
total num of param 2
last status 0
hello mayuan
hello mayuan