3.5.6 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 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.

When available, process substitution is performed simultaneously with parameter and variable expansion, command substitution, and arithmetic expansion.