Linux Learning notes-passing parameters to the Shell

We can pass parameters to the script when we execute the Shell script. The format for getting parameters within a script is: $n. (n represents a number, 0 is the name of the shell script executed, 1 is the first argument to execute the script, 2 is the second argument to execute the script, and so on ...). ）

Examples Show

We first write a script named test.sh, whose contents are as follows:

#!/bin/BashEcho "Shell Output script name and parameters";Echo "name of script executed: $";Echo "The first parameter is: $";Echo "The second parameter is: $-a";Echo "The third parameter is: $ $";

After we give the script permission to run, we run the output:

chmod +x test. SH  $ . /test. SH 1 2 3 Shell Pass Argument instance! The file name to execute:. /test. SH The first parameter is: 1 The second parameter is: 2 The third parameter is: 3

Processing parameter Extensions

In addition to the above usage, we often use these:

parameter Handling	Description
$#	The number of arguments passed to the script
$*	Displays all parameters passed to the script in a single string. such as "$*" 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]	Same as $*, but quoted when used, 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 used by the shell, the same as 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.

Linux Learning notes-passing parameters to the Shell