open3 requires three different file handles for stdin, stdout and stderr. You're attempting to use the same one for stdout and stderr, which I suspect will only cause it to catch data being sent to stderr. Try breaking it up into 3 distinct file handles and deal with both stdout and stderr separately.

Update: My bad, guess you can do it that way.

In reply to Re: Open3 in child process not capturing errors correctly. . by Fastolfe
in thread Open3 in child process not capturing errors correctly. . by geektron

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