[tahoe-lafs-trac-stream] [tahoe-lafs] #2149: "tahoe start" emits an error message when tahoe is already running

[tahoe-lafs]

#2149: "tahoe start" emits an error message when tahoe is already running
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     Reporter:  zooko           |      Owner:  joeyh
         Type:  enhancement     |     Status:  new
     Priority:  normal          |  Milestone:  undecided
    Component:  code-nodeadmin  |    Version:  1.10.0
   Resolution:                  |   Keywords:  usability error cli
Launchpad Bug:                  |
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Comment (by zooko):

 Okay, I guess I consider "do things like other similar daemons do" to be a
 pretty good reason. However, I must say I have no often observed cases
 where writing an error message and setting an exit code when you find the
 thing running was helpful.

 I cannot think of any case that I can recall where that information was
 useful to a caller. "Start if it is not already running" is what I think
 most users want, and "Start if it is not already running, and give me an
 error message if it was already running" is not something I've seen used
 in practice.

 I guess that would be useful for situations where it was important to the
 caller that the thing was previously not-running — so important that the
 caller needs to do something about it. Do what? Kill the running process?
 Call a human for help? If it finds out that the process was already
 running. When would you want to do that about a tahoe-lafs process?

 Now, I ''do'' think it can be useful if the caller is a human using the
 command-line, to get a visual indicator of whether the process was just
 started in response to my manual entry of {{{tahoe start}}} or was already
 running. But for me as a human operator, neither of those things is an
 error, and they should be displayed on stdout as normal messages like
 "Started…" or "Already running…", and the exit code should be set to
 indicate success in both cases.

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2149#comment:7>
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