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<h1><img src="analogo.gif" alt=""> Analog 6.0: Debugging</h1>
<hr size=2 noshade>

This section lists commands to help you debug analog, if you think it's
going wrong. There's another section later which lists all the
<a href="errors.html">errors and warnings</a> which analog can generate,
and what they all mean, and another section which tells you
<a href="mailing.html">how to report bugs</a>.

<p>
First, remember the option we mentioned before, to list the current settings
of all of analog's variables. To get this, just put <kbd>-settings</kbd> on
the command line, or <kbd>SETTINGS ON</kbd> in one of your configuration
files, along with your other commands. Then analog will produce the list of
settings instead of running in the normal way.

<hr size=1 noshade>
<a name="debugs">There are commands</a> which control how much debugging
information and warning
information analog gives out while it is running. By default you get all the
warnings and no debugging, but you can change this by means of the commands
<kbd>DEBUG</kbd> and <kbd>WARNINGS</kbd>. If you say
<pre>
DEBUG ON
</pre>
you get all the debugging. (And <kbd>DEBUG OFF</kbd> turns it all off.)
You can also get just certain categories of debugging. The categories are
<dl compact>
  <dt><kbd>C</kbd><dd>list all corrupt logfile lines
  <dt><kbd>D</kbd><dd>information about DNS lookups
  <dt><kbd>F</kbd><dd>information about file opening and closing
  <dt><kbd>S</kbd><dd>summary information about each logfile when it's closed
  <dt><kbd>U</kbd><dd>list unknown domains
  <dt><kbd>V</kbd><dd>list hosts without a domain (i.e., without a dot)
</dl>
So, for example, the command
<pre>
DEBUG FS
</pre>
would give you information about file opening and closing, and what was in
each logfile, but none of the other sorts of debugging. Each line of debugging
information is prepended with its code letter. You can also specify
<pre>
DEBUG +CD
</pre>
to add <kbd>C</kbd> and <kbd>D</kbd> category debugging to whatever you've
already got, and
<pre>
DEBUG -CD
</pre>
to remove those two categories.
<p>
There is also a command line abbreviation for this command. Use
<kbd>+V</kbd> (for <kbd>ON</kbd>), <kbd>-V</kbd> (for <kbd>OFF</kbd>),
<kbd>+VFS</kbd> (to select exactly options <kbd>FS</kbd>), <kbd>+V+FS</kbd>
(to add those options), and <kbd>+V-FS</kbd> (to remove them).
<p>
The <kbd>C</kbd> messages actually come on two lines. The first line gives the
logfile line which was corrupt. The second line indicates where analog first
noticed a problem. (This is usually, but not always, close to where the
problem
actually was!) In fact, each &quot;line&quot; of the message may spread over
more than one line on your screen, and you have to be careful to take that into
account when trying to find out where the logfile line was corrupt.
<hr size=1 noshade>
<a name="WARNINGS">The <kbd>WARNINGS</kbd></a> command acts similarly to the
<kbd>DEBUG</kbd> command (see the syntax <a href="#debugs">above</a>). By
default all warnings are on. As well as <kbd>WARNINGS ON</kbd> and
<kbd>WARNINGS OFF</kbd>, you can turn warnings on and off in the following
categories.
<dl compact>
  <dt><kbd>C</kbd><dd>invalid configuration specified
  <dt><kbd>D</kbd><dd>dubious configuration specified
  <dt><kbd>E</kbd><dd><kbd>ERRFILE</kbd> command used (see below)
  <dt><kbd>F</kbd><dd>files missing or corrupt
  <dt><kbd>L</kbd><dd>apparent problems in logfiles
  <dt><kbd>M</kbd><dd>possible problems in logfiles
  <dt><kbd>R</kbd><dd>turning off empty reports
</dl>
See the section on <cite><a href="errors.html#warns">Errors and
warnings</a></cite> for more details about the various categories. Again,
warnings are printed with their code letters.
<p>
Warnings range from the probably harmless to the usually serious.
So it is generally not a good idea to turn all warnings off, or you might miss
some important information. If you want to ignore a particular warning, turn
just its category off.
<p>
There is also a command line version of the <kbd>WARNINGS</kbd> command,
looking like <kbd>+q</kbd>, <kbd>-q</kbd>, <kbd>+q&lt;options&gt;</kbd>,
<kbd>+q+&lt;options&gt;</kbd> or <kbd>+q-&lt;options&gt;</kbd>. (The syntax is
the same as the <kbd>+V</kbd> command <a href="#debugs">above</a>.)
<hr size=1 noshade>
<a name="ERRFILE">By default</a> all these messages go to <i>standard
error</i>, which is
normally just the screen. But you can change that by means of a command like
<pre>
ERRFILE newfile
</pre>
If you do this, analog will warn you that it's redirecting the messages, just
so that you don't miss any. To change back to standard error, use
<pre>
ERRFILE stderr
</pre>
The <kbd>ERRFILE</kbd> command will also erase any previous contents of that
file. (So don't use the same <kbd>ERRFILE</kbd> command twice, or you may lose
messages!)
If the name of the <kbd>ERRFILE</kbd> doesn't include a directory, it will be
put in whichever directory was specified for that purpose when the program was
compiled. For example, on Windows it would be in the same folder as the analog
executable.

<hr size=1 noshade>
<a name="ERRLINELENGTH">There is a command</a> called <kbd>ERRLINELENGTH</kbd>
to tell analog the width of screen you want these messages to fit in. As a
special case,
<pre>
ERRLINELENGTH 0
</pre>
specifies an unlimited screen width.

<hr size=1 noshade>
<a name="PROGRESSFREQ">There is one more command</a> which is useful when
trying to debug analog. If you give the command
<pre>
PROGRESSFREQ 20000  # say
</pre>
then analog will produce a little message after every 20,000 lines it reads
from the logfile. (This message is sent to the screen and to the
<kbd><a href="#ERRFILE">ERRFILE</a></kbd>.) This is useful to determine
whether the program has really stopped or (as is more likely) is just being
slow for some reason (such as using DNS lookups).

<hr size=1 noshade>
There is just one more section about analog's configuration commands and
command line arguments, but it's a rather long one, on the
<a href="form.html">form interface</a>. (This is a way of running analog by
selecting options from a web page.) You might prefer to go straight onto the
section on <cite><a href="meaning.html">What the results mean</a></cite>.
<hr size=2 noshade>
Go to the <a href="http://www.analog.cx/">analog home page</a>.
<p>
<address>Stephen Turner
<br>19 December 2004</address>
<p><em>Need help with analog? <a href="mailing.html">Use the analog-help
mailing list</a>.</em>
<p>
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