… what POSIX API gets you the open FDs? (Or even just the maximum open FD, and we'll just cause a bunch of errors closing non-existent FDs.)

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o11c a day ago | parent [-]

That's `sysconf(_SC_OPEN_MAX)`, but it is always an bug to close FDs you don't know the origin of. You should be specifying `O_CLOEXEC` by default if you want FDs closed automatically.

	▲	deathanatos a day ago \| parent [-]
		That won't returned the maximum open file descriptor. You could perhaps use that value in lieu of the maximum open file descriptor and loop through a crap ton more FDs than even my previous post implied, I suppose, and this is getting less efficient and more terribly engineered by the comment, which I think proves the point… > but it is always an bug to close FDs you don't know the origin of. And I would agree. I'm replying to the poster above me, who is staking the claim that POSIX permits closing all open file descriptors other than a desired set. So, I suppose it can, at a cost of a few thousand syscalls that'll all be pointless…