Linux 6.8 Landing A Tantalizing Optimization For Common $PATH-Based Searches

phoronix.com

36 pointsmfiguiere4 comments

It's sort of staggering if you consider how inefficient Unix has been, where every shell script involves several dozen $PATH-based invocations. If you call a given program, say 20 times in a script, and it's located at the third element in $PATH, then that's 40 failed calls to execve(2) that could've been avoided by some sort of caching.

> located at the third element in $PATH, then that's 40 failed calls to execve(2) that could've been avoided by some sort of caching.

Bash caches path lookups and has a command to clear them (i forget its name and am on a tablet, so can't readily check... Maybe "hash" or "rehash"?).

Yes, `hash -r`. You can also use `shopt -s checkhash` to automate this.

(this has not been merged yet, Linus has thoughts[1])

[1] https://lore.kernel.org/lkml/CAHk-=wj1vvUhNd_+s8Cuvh-wO2iT7b...

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