On Wed, Mar 16, 2022 at 07:00:12AM +0700, Robert Elz wrote: > This issue was brought up on the austin-group list (POSIX) by > some doing testing in linux, with output from commands being sent > to /dev/full (yes, a special file whose only purpose, as far as > I can tell, is to return ENOSPC to any write request).
Yes, that's what /dev/full is for. It's surprisingly useful for testing, especially in a world where full disks rarely happen but silent data corruption when it does happen isn't really acceptable. Though with one thing and another a very small tmpfs is probably more useful today. > Anyway, in the next version, POSIX is planning on making it mandatory > for lots of commands to check for write errors on stdout, and if found > exit with a status indicating an error (which also mandates a message > on stderr from almost all utilities). > > I don't much like this, but my arguments fell on deaf ears, so despite > my misgivings, in current, both versions of both echo and printf (the > builtin ones in /bin/sh and the ones in the filesystem) do check for > errors and report them (and exit non-zero) if they happen. > > None of the many other utilities (built into sh, and otherwise) has been > changed, except I think maybe the built-in pwd in sh (not sure if I did > that one or not now) - pwd received a lot of attention because pwd was > the command which (pwd >/dev/full) which started all of this. Reporting ENOSPC (or EDQUOT) and such seems like a considerably different mission from reporting EPIPE, which is noise... but it also wouldn't surprise me to hear that they missed this point. :-| -- David A. Holland dholl...@netbsd.org
