Bird Beak Bash (or process substitution)
http://www.tldp.org/LDP/abs/html/process-sub.html
Process substitution feeds the output of a process (or processes) into the stdin of another process.
<() creates a file descriptor and is most useful when using a command that takes two files as arguments like diff or comm but you want to use output from commands rather than files.
comm <(ls dirA) <(ls dirB)