Pipe data from GRC through shell command (like gr-pipe in 3.6)?

I want to pipe data from GRC “through” a command running in the linux
shell. I found gr-pipe on github, but it seems to be for 3.6 only. Until
now I have used file sinks / sources and FIFOs, but this is inconvenient
as FIFOs have to be created and things have to happen at a specific
place in the filesystem. I’d rather find a way to directly connect to
STDIO of a given command.
thanks Mark

Mark,

The File Descriptor Source/Sink work with stdin/stdout.