Re: GOP-PROP 5: build system output (final)

[Reinhold Kainhofer]

Am Freitag, 5. August 2011, 10:45:15 schrieb Phil Holmes:
> ----- Original Message -----
> From: "Graham Percival" <address@hidden>
> > The standard way for GNU packages to give more output is with a
> > V=x option. Presumably this is done by increasing x? If we support
> > this option, we should still write log files; we would simply
> > print more of the info in those log files to screen.
> 
> My only comment is that it's generally the case that output is directed to
> logfiles using the redirect operator > .  If we do this, it's hard to make
> it also appear on the console (unless someone knows an easy way).  

We can use the 'tee' command for this (it writes the output to a file plus 
copies it to stdout).

One problem is that you cannot distinguish our excessive debug output (a 
simple snippet like "@lilypond[verbatim,quote]{ c'4 }" currently produces 222 
lines of debug output!) from the error messages, once lilypond printed it.

I have a solution in mind, which uses the loglevels, which I'm currently 
polishing. My idea (I'll write a long mail about the loglevels and some future 
desired issues in the next few hours) is to add an option to lilypond to print 
the different messages (errors, warnings, progress, debug, etc.) to different 
file descriptions, so that you can then selectively redirect them (and pipe 
them through tee), so that you can e.g. mirror all errors and warnings on the 
console, write all errors, warnings and progress to a *.log file and at the 
same time write everything to a *.debug.log file.


The keyword is "I/O redirection" for the shell commands, for some technical 
documentation see e.g. the Advanced Bash Scripting Guide:
http://www.faqs.org/docs/abs/HTML/io-redirection.html
http://www.faqs.org/docs/abs/HTML/redirapps.html
http://www.gnu.org/software/bash/manual/bashref.html#Redirections


> I'd not
> noticed the "print info in those log files to screen" bit.  My thoughts
> would be that the general rule is - if you ask for verbose, then you get
> more "Processing xxx.ly file" messages.  You'd then check xxx.log for
> problems.

So, with verbose, you would not get the desired output on the console, but 
need to locate the .log file, open it in a text editor and then search through 
that file?
--verbose usually means to print more on the console, while log files will 
always contain all information.

Cheers,
Reinhold


-- 
------------------------------------------------------------------
Reinhold Kainhofer, address@hidden, http://reinhold.kainhofer.com/
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * LilyPond, Music typesetting, http://www.lilypond.org