Date: Sat, 6 Mar 2021 17:10:45 +0000 From: Arthur Chance <freebsd@qeng-ho.org> To: freebsd-questions@freebsd.org Subject: Re: which is "better" - /dev/fd or FIFO Message-ID: <79db2b71-5758-431d-4654-fc3c42700c68@qeng-ho.org> In-Reply-To: <YEO0gfiytP6n5%2BCD@ceres.local> References: <YEOMzXyvchUkMmdH@ceres.local> <7CEBCD10-90CA-4194-823C-8F87659706BC@kreme.com> <YEO0gfiytP6n5%2BCD@ceres.local>
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On 06/03/2021 16:57, tech-lists wrote: > On Sat, Mar 06, 2021 at 09:37:49AM -0700, @lbutlr wrote: >> On 06 Mar 2021, at 07:08, tech-lists <tech-lists@zyxst.net> wrote: >>> Some ports, notably shells/bash, have a makeoptions config where you can >>> select "enable use of /dev/fd". But there's no explanation given why >>> this is advantageous or not, or if there's some kind of risk, in a >>> freebsd context [1]. It's not enabled by default. Please can anyone >>> explain? >> >> Do you have a floppy drive? > > no. I admit i'd not thought of floppy drive at all. In 2021, who does? Nope, /dev/fd isn't anything to do with floppy disks, that's /dev/fd0 IIRC. > But the context in which this option is in, is confusing. The option is > for fdescfs with "enable use of /dev/fd". I don't know what fdescfs > truly is, apart from something to do with file descriptords, and not > floppy drives. > > Look here to see what I mean: > > https://cloud.zyxst.net/~john/FreeBSD/ports/bashc/bashc.png > > I think "enable use of /dev/fd" might be a bug; maybe it should say > "enable use of /dev/fdescfs" ? > > In which case my question should be "which is best - /dev/fdescfs or fifo?" > If you read the manual entry for fdescfs it says it should be mounted via mount -t fdescfs null /dev/fd Opening /dev/fd/N gives you an alternate access path to file descriptor N in your program. I.e. opening /dev/fd/0 gives you access to stdin but on a different fd. -- The number of people predicting the demise of Moore's Law doubles every 18 months.
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