On the shell, it is all the other way around, so to use command substitution it is like this:

    f $(g x)

To pass the output of g x to f.

is it? In practice I find that my shell one liners are orders of magnitude more complex than what I would dare to write in any other 'proper' language:

   grep "hello ($(cat patterns.txt| tr '\n' '|'|grep ')$^)"  <(ssh other.host "cat ~/file.txt") |tee >(grep 'a' >As.txt) >(grep 'b' > Bs.txt)

[yes, gratuitous use of cat, sue me]