Parameter passing of the shell

We can pass parameters to the script when executing the Shell script, and the format of the parameters obtained in the script is:$n. n represents a number, 1 is the first argument to execute the script, 2 is the second argument to execute the script, and so on ...

Instance

In the following example, we pass three parameters to the script and output them separately, where the file name is executed:

#!/bin/bash# Author: Rookie Tutorial # url:www.runoob.com"Shell pass parameter instance! "; "file name executed: $";" The first parameter is: $ ";" The second parameter is: $ ";" The third parameter is: $ $ ";           

Set executable permissions for the script and execute the script with the output as follows:

+x Test: /test.  123Shell pass parameter instance! Execute the file name:./test.  SH The first parameter is:1 The second parameter is:2 the third parameter is:3         

In addition, there are several special characters for handling parameters:

The

parameter handling	description
$#	The number of arguments passed to the script /td>
$*	Displays all parameters passed to the script in a single string. such as "$*" in the Case of "" ", in the form of" $ $ ... $n "output all parameters.
$$	The current process ID number for the script to run
$!	ID number of the last process running in the background
[email protected]	is the same as $*, but is used with quotation marks and returns each parameter in quotation marks. such as "[email protected]" with "" "in the case, with" $ "" $ "... All parameters are output in the form "$n".
$-	Displays the current options that the shell uses, as is the SET command function.
$?	displays the exit status of the last command. 0 means there is no error, and any other value indicates an error.

#!/bin/bash# Author: Rookie Tutorial # url:www.runoob.com"Shell pass parameter instance! "; "The first parameter is: $"; The number of parameters is: $# ";" The passed arguments are displayed as a string: $* ";         

Execute the script with the output as follows:

+x Test: /test.  123Shell pass parameter instance! The first parameter is:1 the number of arguments is:3 The parameters passed as a string display:123      

$* and [email protected] Difference:

• The same point: all parameters are referenced.
• different points: only in double quotes. Assuming that three parameters 1, 2, 3 are written when the script is run, "*" is equivalent to "1 2 3" (one parameter is passed), and "@" is equivalent to "1" "2" "3" (three parameters are passed).

#!/bin/bash# Author: Rookie Tutorial # url:www.runoob.comecho "--\$* Demo---"for i in "$* ";  Do   echo $idoneecho "-\[email protected] Demo---" For i in  "[Email Protected] ";  Do  echo $i               Done 

Execute the script with the output as follows:

$ chmod+X testsh $ ./test.1 2 3 -- $*  Demo  ---12 3--  [email protected]  demo  --- 12 3                  

Parameter passing of the shell