Joerg Schilling <joerg.schill...@fokus.fraunhofer.de> wrote, on 27 Jun 2019: > > Stephane Chazelas <stephane.chaze...@gmail.com> wrote: > > > Today, by your reading of the spec and I agree it can be seen as > > a valid reading, the spec is telling me that: > > > > 1. > > > > a='\.' > > printf '%s\n' $a > > > > is a portable script that is meant to output "." > > I know just one single shell that outputs "." with this code. > > This is bash5. Note that POSIX is a portable source standard and other shells > that may behave like bash5 currently only compile and work on a single > platform. > > My impression is that this is mainly supported by Geoff
That was my initial position, but we have moved on since then. I am willing to accept the compromise currently being discussed whereby pathname expansion only happens when there is an unquoted '*', '?' or '[' in the pattern, in which case the above would be required to output '\.' I updated the proposal in the etherpad accordingly. > > 2. > > > > a='\**' > > printf '%s\n' $a > > > > is a portable script that is meant to list the filenames that > > start with "*" in the current directory > > See 1), there is just one shell that behaves this way. And that shell is "bash" (not just "bash5"). All versions I tried do it (including bash3 on macOS). > > 1 and 2 is the reason I raised bug 1234. 1 couldn't be furthest > > away from the truth. Only bash5 exhibits that behaviour and it's > > evident it's a bad idea. It's evident that it was not the > > intention of the spec as no shell at the time it was written did > > This is very important, as POSIX does not claim to do own invention. This is simply not true in the case of POSIX.2-1992, and I have corrected you on that before. POSIX.2-1992 deliberately made a number requirements that forced implementations to change, including some that were invention (an obvious one being pax). > > 2 is slightly more portable, but even in those shells where it > > does that, that's not because they implement \ processing the > > way POSIX seems to specify it, and all do it a different way. > > I'm not opposing POSIX *allows* a \ in an unquoted word > > expansion to have a special meaning when it's preceding *, ? and > > [ as that's what several implementations do and it's not > > breaking that many common shell usages. > > I see no real difference to 1). The only portable shell that behaves this way > is bash5. No, all versions of bash back to at least 3.2 behave that way. -- Geoff Clare <g.cl...@opengroup.org> The Open Group, Apex Plaza, Forbury Road, Reading, RG1 1AX, England
