Output Channels

From 170d0d6f375241e0d0ca85a1327df82165fec439 Mon Sep 17 00:00:00 2001 From: Rainer Gerhards Date: Tue, 11 Nov 2008 11:00:37 +0100 Subject: added forgotten files they were new after restructuring the doc... --- doc/rsyslog_conf_output.html | 81 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 doc/rsyslog_conf_output.html (limited to 'doc/rsyslog_conf_output.html') diff --git a/doc/rsyslog_conf_output.html b/doc/rsyslog_conf_output.html new file mode 100644 index 00000000..c52aaa5e --- /dev/null +++ b/doc/rsyslog_conf_output.html @@ -0,0 +1,81 @@ + +Output Channels - rsyslog.conf + +

This is a part of the rsyslog.conf documentation.

+back +

Output Channels are a new concept first introduced in rsyslog +0.9.0. As of this writing, it is most likely that they will +be replaced by something different in the future. So if you +use them, be prepared to change you configuration file syntax when you +upgrade to a later release.
+
+The idea behind output channel definitions is that it shall provide an +umbrella for any type of output that the user might want. In essence,
+this is the "file" part of selector lines (and this is why we are not +sure output channel syntax will stay after the next review). There is a
+difference, though: selector channels both have filter conditions +(currently facility and severity) as well as the output destination. +they can only be used to write to files - not pipes, ttys or whatever +Output channels define the output definition, only. As of this build, +else. If we stick with output channels, this will change over time.

In concept, an output channel includes everything needed to +know about an output actions. In practice, the current implementation +only carries
+a filename, a maximum file size and a command to be issued when this +file size is reached. More things might be present in future version, +which might also change the syntax of the directive.

Output channels are defined via an $outchannel directive. It's +syntax is as follows:
+
+$outchannel name,file-name,max-size,action-on-max-size
+
+name is the name of the output channel (not the file), file-name is the +file name to be written to, max-size the maximum allowed size and +action-on-max-size a command to be issued when the max size is reached. +This command always has exactly one parameter. The binary is that part +of action-on-max-size before the first space, its parameter is +everything behind that space.
+
+Please note that max-size is queried BEFORE writing the log message to +the file. So be sure to set this limit reasonably low so that any +message might fit. For the current release, setting it 1k lower than +you expected is helpful. The max-size must always be specified in bytes +- there are no special symbols (like 1k, 1m,...) at this point of +development.
+
+Keep in mind that $outchannel just defines a channel with "name". It +does not activate it. To do so, you must use a selector line (see +below). That selector line includes the channel name plus an $ sign in +front of it. A sample might be:
+
+*.* $mychannel
+
+In its current form, output channels primarily provide the ability to +size-limit an output file. To do so, specify a maximum size. When this +size is reached, rsyslogd will execute the action-on-max-size command +and then reopen the file and retry. The command should be something +like a log rotation +script or a similar thing.

If there is no action-on-max-size command or the command did +not resolve the situation, the file is closed and never reopened by +rsyslogd (except, of course, by huping it). This logic was integrated +when we first experienced severe issues with files larger 2gb, which +could lead to rsyslogd dumping core. In such cases, it is more +appropriate to stop writing to a single file. Meanwhile, rsyslogd has +been fixed to support files larger 2gb, but obviously only on file +systems and operating system versions that do so. So it can still make +sense to enforce a 2gb file size limit.

+ +

[manual index] +[rsyslog.conf] +[rsyslog site]

+ + + + -- cgit v1.2.3