Process Substitution (Bash Reference Manual)
3.5.6 Process Substitution
Process substitution allows a process’s input or output to be referred to using a filename. It takes the form of
list is run asynchronously, and its input or output appears as a filename. This filename is passed as an argument to the current command as the result of the expansion. 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 output of
list. Note that no space may appear between the
> and the left parenthesis, otherwise the construct would be interpreted as a redirection. Process substitution is supported on systems that support named pipes (FIFOs) or the
/dev/fd method of naming open files.
When available, process substitution is performed simultaneously with parameter and variable expansion, command substitution, and arithmetic expansion.