aggregate: Write timestamp next aggregation can happen to .ikiwiki/aggregatetime, to allow for more sophisticated cron jobs.

1 files changed, 12 insertions, 3 deletions

diff --git a/doc/plugins/aggregate.mdwn b/doc/plugins/aggregate.mdwn
index bb828b05c..2925b6fba 100644
--- a/doc/plugins/aggregate.mdwn
+++ b/doc/plugins/aggregate.mdwn
@@ -5,9 +5,13 @@ This plugin allows content from other feeds to be aggregated into the
 wiki. To specify feeds to aggregate, use the
 [[ikiwiki/directive/aggregate]] [[ikiwiki/directive]].
 
-The [[meta]] and [[tag]] plugins are also recommended. Either the
-[[htmltidy]] or [[htmlbalance]] plugin is suggested, since feeds can easily
-contain html problems, some of which these plugins can fix.
+## requirements
+
+The [[meta]] and [[tag]] plugins are also recommended to be used with this
+one. Either the [[htmltidy]] or [[htmlbalance]] plugin is suggested, since
+feeds can easily contain html problems, some of which these plugins can fix.
+
+## triggering aggregation
 
 You will need to run ikiwiki periodically from a cron job, passing it the
 --aggregate parameter, to make it check for new posts. Here's an example
@@ -15,6 +19,11 @@ crontab entry:
 
 	*/15 * * * * ikiwiki --setup my.wiki --aggregate --refresh
 
+The plugin updates a file `.ikiwiki/aggregatetime` with the unix time stamp
+when the next aggregation run could occur. (The file may be empty, if no
+aggregation is required.) This can be integrated into more complex cron
+jobs or systems to trigger aggregation only when needed.
+
 Alternatively, you can allow `ikiwiki.cgi` to trigger the aggregation. You
 should only need this if for some reason you cannot use cron, and instead
 want to use a service such as [WebCron](http://webcron.org). To enable