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Re: Debug output etc, cluttering the terminal


Neil Williams <codehelp@debian.org> writes:

> On Sun, 15 Aug 2010 08:51:21 +0200
> Michael Welle <mwe012008@gmx.net> wrote:
>> > It's debug output, it is useful when debugging and you need the
>> > output, e.g. when fixing bugs and the user can just be asked to run
>> > the command from the terminal and post the output to help in
>> > debugging the bug report. Generally, the debug output for a
>> > particular release tends to reflect the issues which upstream were
>> > working on most intensively before that release and therefore can
>> > have a direct impact on the likelihood of new bugs or regressions
>> > in old bugs.
>> >
>> > It's not clutter. If you don't want to see it, run the command and
>> > redirect stderr.
>> I agree with your opinion about the usefulness of debug output. And
>> -as one might guess- I disagree with your opinion about  how debug
>> output should be handled. Do Debian distribute programmes to its user
>> base, that are still in debug phase?
> Yes and will continue to do so. All software is susceptible to bugs and
> all software needs to have debug support. Mature software needs more
> debug support than pre-alpha software because bugs in mature packages
> tend to be corner-cases and obscure use cases, i.e. harder to identify.
> Every software package is constantly being debugged. Even the kernel
> produces debug output in the case of particular errors - including
I haven't seen that the kernel is constantly filling my terminals or the
log files with that kind of messages that I have quoted in my first
posting. If an application traps into an error condition and then
dumps its state I'm fine with that.

> messages which appear on every terminal on the machine and sound a
> fixed volume beep. Depending on the circumstances, this can be
> something as simple as not taking a USB networking interface down
> before removing the USB cable. Depends which module is in use.
>> Aren't debug switches sold
>> anymore?
> "sold" ??? Programs support --debug or --verbose options on the command
> line for debugging of errors which are not often seen.
I have the feeling (again, no numbers here) that the number of cases were
such output is grabbed, attached to a proper bug report and then results
in a solution of the bug is virtualy zero. Why? Well, one starts the
application, the application crashes. One wonders, starting the
application again to see what happens. Now the application might work or
it had eaten the data base. In both cases it is unlikely that you can
find the relevant output in your terminal, if it is still open.

>> One can forget to switch debug output off. That's no biggy,
>> mistakes happen. But have it switched on per default is strange and
>> embarassing.
> Nothing of the sort. Programs that do not provide debug output should
> make log files containing debug output.
That is the point. I work at an application that can produce gigbytes of
logs per day. From the logs you can reconstruct everything the system
had done, even the data that flowed between the server and its
clients. But it uses files for logging and a sane default log
level. Potential customers would kick my ass if the system would behave
different ;).

> When bugs are hard to reproduce, having debug output on by default is
> extremely important for many mature packages.
Why don't clutter Emacs, gv, X, sed, perl, openoffice (I don't know
for sure) etc. pp. the terminals with such debug messages?

> This isn't about forgetting to switch debugging off, this is about
> helping users and developers actually fix bugs.


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