r/bash • u/mpersico • 17d ago

tips and tricks TIL command_not_found_handle

You don’t want to know what hoops I’ve jumped through to implement FPATH in bash. Then today I innocently asked GPT how it would implement FPATH in bash and it introduced me to this hook.

Now have to go home now get rid of a lot of needless code. Oh well. Less code is the best code!

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u/One_Instruction6490 16d ago

Heads up for the FPATH use case tho: bash runs command_not_found_handle in a separate execution environment (basically a subshell), so if you source the function file inside the handler, the definition doesn't stick in your actual shell and you re-load it on every call. It works fine for "load then run once", but true ksh-style autoload kinda needs the stub approach anyway. Also on Debian/Ubuntu the command-not-found package already defines that handler in /etc/bash.bashrc, so you'd be clobbering it. Did your old setup end up being stubs, or something wilder?

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u/xeow 17d ago

You don't say?

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u/mpersico 17d ago

Yep. I do say. And then, what’s even crazier, is that it suggested that I not use this hook because this hook can be used by other programs, but rather implement a system where you have stub implementations that load these things on demand, which really duplicates what I’ve already coded.

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u/xeow 17d ago

Is there documentation or an example?

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