Computing life would be tedious if you had to repeat the same command on multiple files. After all, aren’t repetitive tasks what the computer was designed to do? Wildcard expansion refers to the ability of one command to be executed against many files. The asterisk (*) and the question mark (?) are two wildcard characters that are used to match any filename, or a portion of a filename. For example, you can use the following command to see a long directory listing that includes only files that end with a .doc filename extension:
ls -l *.doc
The files listed may include resume.doc, cover_letter.doc, and to_editor.doc, for example.