On Tue, Jul 07, 2020 at 07:41:51AM -0400, Greg Wooledge wrote: > On Mon, Jul 06, 2020 at 09:45:59PM -0400, Dale R. Worley wrote: > > bug-b...@trodman.com writes: > > > foo | tee >(cat >&2) | bar > > > > I do wonder how portable >( ... ) is in practice, versus the portability > > of /dev/stderr. Maybe I worry about the former because I'm not > > practiced in named-FIFO programming and so think of it as non-universal. > > On Linux and BSD systems, >( ) will use a /dev/fd/ entry. On most > commercial Unix systems, where /dev/fd/ does not exist, it will use a > named pipe in /var/tmp. On a hypothetical system where neither one is > available (Microsoft Windows?), I believe it may use a temp file. That > decision is made at bash's compile time. > > The semantics of /dev/fd/* and named pipes are not quite identical, so > if you're relying on some very *special* mechanisms, then there could > indeed be portability issues. For most scripts, however, it shouldn't > matter.
Oh, the other thing I forgot to mention is that the semantics of /dev/fd/* differ between Linux and BSD. I don't have a reference available off the top of my head, but at some time in the past few years, it came up on one of the bug-bash or help-bash mailing lists -- someone's script acted differently on BSD than it did on Linux because of the different implementation of /dev/fd/ as used by a process substitution. People do *weird* shit with bash. The really surprising part is that they don't *think* it's weird.
