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Process substitution allows a process’s input or output to be referred to using a filename. It takes the form of
<(list)
or
>(list)
The process 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 < or >
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.