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| author | Rainer Gerhards <rgerhards@adiscon.com> | 2009-11-10 13:50:07 +0100 |
|---|---|---|
| committer | Rainer Gerhards <rgerhards@adiscon.com> | 2009-11-10 13:50:07 +0100 |
| commit | b4dd4ef83a51bc91a5861c0dd2809263e60cd05d (patch) | |
| tree | 65cd4e49a9ecf27476009149666e7a6ddb738dba | |
| parent | 2b5e15d549940c7ace9017eaf40d523e3741c9a2 (diff) | |
| download | rsyslog-b4dd4ef83a51bc91a5861c0dd2809263e60cd05d.tar.gz rsyslog-b4dd4ef83a51bc91a5861c0dd2809263e60cd05d.tar.xz rsyslog-b4dd4ef83a51bc91a5861c0dd2809263e60cd05d.zip | |
doc: added reasoning for why use env vars to configure debug system
| -rw-r--r-- | doc/debug.html | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/doc/debug.html b/doc/debug.html index 3803be1a..46759986 100644 --- a/doc/debug.html +++ b/doc/debug.html @@ -1,5 +1,6 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> -<html><head> +<html> +<head> <meta http-equiv="Content-Language" content="en"> <title>Rsyslog Debug Support</title></head> <body> @@ -51,6 +52,24 @@ debug output itself. You need to send SIGUSR1 to turn it on when desired. <li><b>help</b> - display a very short list of commands - hopefully a life saver if you can't access the documentation...</li> </ul> </ul> +<h3>Why Environment Variables?</h3> +<p>You may ask why we use environment variables for debug-system parameters and not +the usual rsyslog.conf configuration commands. After all, environment variables force one +to change distro-specific configuration files, whereas regular configuration directives +would fit nicely into the one central rsyslog.conf. +<p>The problem here is that many settings of the debug system must be initialized +before the full rsyslog engine starts up. At that point, there is no such thing like +rsyslog.conf or the objects needed to process it present in an running instance. +And even if we would enable to change settings some time later, that would mean that +we can not correctly monitor (and debug) the initial startup phase of rsyslogd. What +makes matters worse is that during this startup phase (and never again later!) some +of the base debug structure needs to be created, at least if the build is +configured for that (many of these things only happen in --enable-rtinst mode). So +if we do not initialize the debug system <b>before</b> actually startig up the +rsyslog core, we get a number of data structures wrong. +<p>For these reasons, we utilize environment variables to initialize and configure +the debugging system. We understand this may be somewhat painful, but now you know +there are at least some good reasons for doing so. <h2>Getting debug information from a running Instance</h2> <p>It is possible to obtain debugging information from a running instance, but this requires some setup. We assume that the instance runs in the background, so debug output to @@ -122,4 +141,5 @@ instance of rsyslogd can be aborted by pressing ctl-c. Copyright © 2008, 2009 by <a href="http://www.gerhards.net/rainer">Rainer Gerhards</a> and <a href="http://www.adiscon.com/">Adiscon</a>. Released under the GNU GPL version 3 or higher.</font></p> -</body></html> +</body> +</html> |