[andreyv]

> So there is no way to abort a bash script if something like <(sort nonexistent) fails.

The process ID of the last executed background command in Bash is available as $!.

  cat <(sort nonexistent)
  wait $! || echo fail

gives

  sort: cannot read: nonexistent: No such file or directory
  fail

[mkdirp]

> The process ID of the last executed background command in Bash is available as $!.

After a quick search it doesn't seem like this is an option for anything but the last executed background process. So if you have the typical `diff <(left) <(right)`, there is no easy way to get the pid of `<(left)`.

I suppose you could output the pid to a file, and use it from there, though I haven't tested if that would work.