Hello there! I am exploring ways of running external programs via Elixir, and to my surprise I didn’t found a way to read from called program’s stdout and stderr separately. It seems that this is related to how Erlang primitives are handling that task. Only thing I found, is open_port/2’s stderr_…

Welcome to the forum! Have you had a look at this yet (if you were thinking about pipes)? [image] How can I send a process a message from a shell script? Questions Is there a straightforward way to send a message to my Elixir process from a bash script? To a…

Hi @peerreynders , thank you for the response! With my current knowledge of Elixir I guess that I can try to achieve what I want with - for example - 2 named pipes or named pipe plus stderr or stdout? All the moving parts around it seem to me bit intimidating. Following links mentioned in the threa…

While back from 2015 this may still be of some help: The Erlangelist: Outside Elixir: running external programs with ports by Saša Jurić, author of Elixir in Action 2e .

For note, Port’s are more for running with programs designed to work with your BEAM program, it’s less for running ‘other’ things as it doesn’t have this control over file descriptors, PID handling, or anything. If you want to manage programs that aren’t designed to be Port programs then I recommen…

Thank you for the reply, much appreciated @OvermindDL1 . Yes, that’s the module I’ve found, but I was searching something more lightweight, native, so to speak, but after your post I think I understand situation better. As a side-note - it feels quite exotic to me, I’ve never encountered such desig…

[image] fmn: Yes, that’s the module I’ve found, but I was searching something more lightweight, native, so to speak, but after your post I think I understand situation better. Yeah that is the native way here. ^.^ The only way to do mutability on the BEAM (short of some hacks) is via messag…

You can also look at porcelain with or without goon plugin which despite its age still works well for me when I needed stdin control beyond what System.cmd can provide without digging into low-level Ports. That said erlexec is better maintained and I found (but not tried) a more idiomatic Elixir wr…

There is also rambo which might come in handy as an alternative to porcelain and goon, as it’s wrapper does not use go and it’s runtime…

I had a similar problem, what I did was to pipe stderr to a temp file. A bit ugly, but it worked from what I remember :stuck_out_tongue:

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Stderr and stdout of external program

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fmn October 3, 2019, 5:15pm 10

Thank you for all of the suggestions folks!