$* means substitute all the parameters supplied to the alias and $0 refers to the alias name. For example, the command:

defines a command to do a screen dump (print the screen contents) and (because of the $*) allows users to specify print options with the screendump command. For example, you could print the screen contents by typing:

The following command would print the screen contents, but it would add page numbers to the header and a date stamp to the footer:

You can also use symbolic parameters to substitute part of an option. For example, to define a command that opens (for editing) a document in the directory /user/xxx, issue the command:

If you were editing a document in a different directory and issued the command homedir todo, your document would be replaced with the document todo from directory /user/xxx.

To simplify things even more, you can shorten the name of your new command from homedir to hd by typing:

To edit todo, enter hd todo.

The $0 symbolic parameter will substitute the alias name within the alias invocation itself. For example:

Running the testecho alias would generate the following response: