[daragh]

That FIFO temporary file is the file descriptor of the subprocess' stdout. You're accessing it through a pipe.

It's most useful when you want to diff the result of multiple commands, e.g.: diffing the contents of two directories:

  $ diff <(find /first/path | sort) <(find /second/path | sort)

[akldfgj]

Aha!

In zsh "=(cmd)" does that, but "=" doesn't work in bash. "<(cmd)" works everywhere... why did zsh trick me with "="?

[ralph]

zsh had the idea first IIRC.