From man bash
:
Process Substitution
Process substitution is supported on systems that support
named pipes (FIFOs) or the /dev/fd method of naming open
files. It takes the form of <(list) or >(list). The process
list is run with its input or output connected to a FIFO or
some file in /dev/fd. The name of this file is passed as an
argument to the current command as the result of the expan‐
sion. If the >(list) form is used, writing to the file will
provide input for list. If the <(list) form is used, the
file passed as an argument should be read to obtain the out‐
put of list.
You can search manpages by pressing /
and then typing your search string, which is a good way of finding information like this. It does of course require that you know in which manpage to search :)
You have to quote the (
though, because it has a special meaning when searching. To find the relevant section in the bash manpage, type />\(
.