Auto-complete command line arguments

Question

In bash, executables such as mplayer and imagemagick's "convert" have a cool auto-complete functionality on their command line arguments. For instance, if I type

mplayer <tab><tab>

in one of my folder, then mplayer will list all media files located in that folder, and only the media files.

Similarly, if I type

convert -<tab><tab>

then I will see all the possible options of the convert script, which is great.

My question is how to achieve a similar functionality, using bash, ruby or python scripts?

Answer 1

This is an example of BASH's smart completion. A basic description is here, a guide to writing your own extensions is here and another (Debian-based) guide is here. And here's a fuller featured introduction to the complete command (the command the facilitates this behaviour).

Answer 2

This functionality in bash is provided by bash-completion and similar functionality is included in zsh. If you want to add support for some program not currently supported by one of these tools, you need to write your own extensions for them.