China DOS Union

The code you provided is a batch script related to network configuration and Ghost operations.

For the line `if not "%windir%*"=="*" goto Error`, it's checking if `%windir%` (which is the path to the Windows directory) concatenated with an asterisk is equal to an asterisk alone. Effectively, it's a way to check if `%windir%` is not an empty string. Because if `%windir%` is set (i.e., we're in Windows), then `%windir%*` will be something like `C:\Windows*` which is not equal to `*`, so it will not go to the `Error` label. If `%windir%` is empty (i.e., we're in DOS), then `%windir%*` is just `*`, so it will go to the `Error` label.

For the line `if "%3*"=="*" goto Sample`, it's checking if the third command-line argument (`%3`) concatenated with an asterisk is equal to an asterisk alone. This is a way to check if the third command-line argument is empty. If the third argument is empty, then it will go to the `Sample` label.

So, in summary:

The `*` is used as a way to concatenate with the variable value to perform a check for the presence or absence of the variable's value. The first check is to see if we're in Windows (by checking if `%windir%` is set), and the second check is to see if the third command-line argument is provided.

In fact, the * here is redundant. When using if to judge whether an environment variable is an empty string, in order to prevent the environment variable from being empty and causing "if %var%==1" to appear as "if ==1", generally, one or more characters are added around the variable to prevent it. The most common way is to enclose the environment variable in double quotes, for example, if "%windir%"==""". Of course, you can also use if %windir%#==# or if %windir%*==* instead of double quotes.

Heheh, thanks,大侠climbing! It turns out that `if not "%windir%*"=="*"` is to prevent `%windir%` from being empty, leading to a situation where `if not ==*` occurs

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