Hi Martin, arguing that this is unrelated to osmocom, but relevant to GNU Radio: I'm CC'ing the discuss-gnuradio mailing list [1]; I'll recommend following up there (and taking osmocom-sdr out of CC: when doing that), unless someone else sees an argument for keeping this discussion here. So, GNU Radio as a framework doesn't set any constraints on what the scheduler and blocks do to stdout; especially, the default logger writes to stdout, so, no matter how you do it, putting the output onto stdout doesn't work out; it's a shared resource across all components in GNU Radio. Yes, but you can only have graphs that are paths this way. GNU Radio allows for arbitrary cycle-free graphs. So, this only solves a small subset. It's a mature solution, but for a much smaller problem space, i.e. not generally applicable to GNU Radio. You put this very nicely! You're saying: and that's the whole point: Unix shell piping can create *strings* of processing steps. GNU Radio can do more than that – thus, we never implemented something different. I'd argue that GNU Radio's python interface allows you to execute top_block.connect(source_block, processing_block1, processing_block2, sink_block) top_block.run() so, that's a pretty text-based approach :) Don't forget that it essentially doesn't matter to your OS whether you run a bash script or a python script – and in this case, python has the tools that bash is lacking to create complex flow graphs. So, what to recommend? First of all, you don't *have* to use GRC to create your flow graphs. Many of us do, because it gives you kind of a graphical representation of the Python program that GRC generates and thus is kind of self- documenting, but really, just write Python :) You'll find that you can read the flow graph programs that GRC generates pretty well, and base your programs on that. No matter how you set up your GNU Radio flow graph, it's a very valid use case to want something like python flowgraph.py | grep "alert" > warnings.txt you can actually do that by /bin/bash TEMPDIR=$(mktemp -d) mkfifo "${TEMPDIR}/fifo" python flowgraph.py --filename "${TEMPDIR}/fifo" & grep "alert" < "${TEMPDIR}/fifo" > warnings.txt The magic happens in your flowgraph, where you'd add a "Parameter" block to add your "--filename" option, and use that option for the file name in a file sink :) Hope that helps, Marcus [1] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio On Sun, 2018-08-19 at 13:47 -0500, Martin McCormick wrote: