As the shell developer cannot know in advance which commands and programs you'll use, it becomes a problem of providing a good way for developers to provide the

As the shell developer cannot know in advance which commands and programs you'll use, it becomes a problem of providing a good way for developers to provide the shell a way to inspect and complete. Bash has a very good way of doing that. Actually Debian based distributions have very good completion scripts. git, apt and other very used programs have good completion. Is up to the developer.