Implementation principle and code example of Linux shell passing parameters

Time:2021-1-26

Shell pass parameters

When executing shell script, we can pass parameters to the script. The format of parameters obtained in the script is $n. N represents a number, 1 is the first parameter to execute the script, 2 is the second parameter to execute the script, and so on

In the following example, we pass two parameters to the script and output them respectively, where $0 is the file name to execute:

Special character parameters

$# the number of arguments passed to the script

$* displays all parameters passed to the script as a single string, such as “1 2 3”

$$the current process ID number of the script running

$! The ID number of the last process running in the background

[email protected] displays all parameters passed to the script as multiple strings, such as “1” “2” “3”

$- displays the current options used by the shell, andSet commandIt has the same function.

$? Displays the exit status of the last command. 0 indicates no error, any other value indicates an error.

The difference between $* and [email protected]

 

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