Calling external programs from GRC flowgraphs

GNU Radio
1

I have a GRC app doing some decoding, having tried had but failed to
write a block (its far too difficult) I realise I only need to call a
program to handle the data dumped into a fifo by the GRC application.
That is, effectively run an executable with some command line options.
Is this possible?

Mike

2

Mike W. wrote in post #1113973:

I have a GRC app doing some decoding, having tried had but failed to
write a block (its far too difficult) I realise I only need to call a
program to handle the data dumped into a fifo by the GRC application.
That is, effectively run an executable with some command line options.
Is this possible?

Mike

Hi Mike,

This should be possible.
Within grc write the data to stream_out.fifo (e.g).
In your program, read in the data via stdin. Then you can use a pipe to
pass the data from fifo to your external program
(start this before running grc app):
cat stream_out.fifo | my_application -options

Hope this helps.

3

Friedemann Stockmayer wrote in post #1114346:

Mike W. wrote in post #1113973:

I have a GRC app doing some decoding, having tried had but failed to
write a block (its far too difficult) I realise I only need to call a
program to handle the data dumped into a fifo by the GRC application.
That is, effectively run an executable with some command line options.
Is this possible?

Mike

Hi Mike,

This should be possible.
Within grc write the data to stream_out.fifo (e.g).
In your program, read in the data via stdin. Then you can use a pipe to
pass the data from fifo to your external program
(start this before running grc app):
cat stream_out.fifo | my_application -options

Hope this helps.

Thanks for the reply - possibly I wasn’t clear enough. I am already
using the FiFo as you suggest, but I want to call the program (an AX25
packet decoder with UDP outputs) from within the GRC flowgraph - that is
presumably using a block that initiates another program. Otherwise it
means the user having to understand how to start a program in another
window at the right time in the proceedings.

Mike