Restricted tab-completion is annoying

Ian Jackson iwj at
Mon Oct 15 16:46:47 UTC 2007

Aaron C. de Bruyn writes ("Restricted tab-completion is annoying"):
> Today a website generated a PDF file for me automatically and
> firefox popped up and asked if I wanted to download it.  I hit 'OK'
> and it saved 'genpdf.asp' into my downloads folder.  I was surprised
> to find bash wouldn't tab-complete the filename.

I too find the programmable completion very annoying.

The way an experienced user uses completion (and note that on the
command-line we're intended to support experienced users) depends
critically on it being 100% predictable: the user will sometimes
partially tab-complete and then continue typing and perhaps even hit
return before any information about malfunction of the completion has
time to have been processed.

Predictability is far far more important than functionality for
completion to be an effective useability aid.

Context-specific completion nearly always results in additional
unpredictability - not just due to bugs (which are rife), but the
behaviour is changed every time a new completion is added, or an
existing bug in the completion is fixed.

Since completion needs to be and remain compatible with our
finger-macros (muscle memory), and we can't update our fingers, we
mustn't change or update completion either.

So I submit that programmable completions should be off by default.


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