It terminates argument parsing, so anything following it that starts with a hyphen will not be treated as an argument. $ echo 'hack the planet' > --help

It terminates argument parsing, so anything following it that starts with a hyphen will not be treated as an argument. $ echo 'hack the planet' > --help $ cat --help cat: illegal option -- - usage: cat [-belnstuv] [file ...] $ cat -- --help hack the planet $ rm -vf --help rm: illegal option -- - usage: rm [-f | -i] [-dIPRrvWx] file ... unlink [--] file $ rm -vf -- --help --help $ cat -- --help cat: --help: No such file or directory