[hmng]

Isn't that what tee is for? Like

$ prog | tee /tmp/log.txt

[jmclnx]

When I submit a process to bg, I mostly use cron and I do not care about seeing output during runtime.

So, tail suites my needs in the rare cases something unexpected seems to be happening.

[gosub100]

That's if you start the process with advance knowledge that you'll want to tail the output and log it. Not if you want to view the output of an existing process

[hmng]

Yes, but I was replying to the above, using redirection and tail -f.