The asterisk matches any number of characters, including no characters. Microsoft's DOS borrowed these from Unix, so you may have seen them before. Standard input is a file from which a program can receive input. The default is usually the characters you type on the terminal screen. The default is usually the terminal screen.
Standard error is a file to which a program can send errors.
The default is usually the terminal screen. Unix often assumes that you know exactly what you want to do, and will at times happily overwrite existing files when you redirect output to them, copy to them, etc. Be SURE to know where you are putting things. Permissions The Unix operating system has ways to control the read, write, and execute modes of files and directories by user names and by groups to which users can belong. The owner of the file and the group to which he or she belongs is also listed.