Most GNU utilities share the options listed in Table VI-2. The utilities that use these options are marked as such. Almost all POSIX utilities support the and options.
Table VI-2. Common command line options
A single hyphen appearing in place of a filename indicates that the utility will accept standard input in place of the file.
A double hyphen marks the end of the options on a command line. You can follow this option with an argument that begins with a hyphen. Without this option the utility assumes that an argument that begins with a hyphen is an option.