To use the pubsub command, first launch the Terminal application.
To list all RSS feed clients type:
pubsub list clients
You'll get results like this:
#Feeds Signature 9 com.apple.Safari 0 com.apple.mail
pubsub list
To list RSS feeds for a particular client type:
pubsub --client com.apple.Safari list
Either way, the pubsub list command returns the following RSS feed information:
Title -Name URL -URL Interval -Refresh /Expiry times
pubsub refresh http://rss.feed.url
For more pubsub command information type:
man pubsub
Using this information I wrote a quick AppleScript to refresh all of my Safari RSS feeds. Here it is:
--GET ALL RSS FEED URLS
set theURLs to paragraphs of ¬
(do shell script "pubsub --client com.apple.Safari list|awk -F'" & tab & "' '{print $3}'|grep http:")
--UPDATE THE RSS FEEDS ONE BY ONE
repeat with aURL in theURLs
do shell script "pubsub refresh " & quoted form of aURL
end repeat
I don't have any RSS feeds in the Mail application, but you can easily modify the AppleScript to update the RSS feeds of a different client or all clients.
[crarko adds: I mostly tested this one. The AppleScript compiles and runs and the pubsub command does what the hint says. It doesn't appear to work with NetNewsWire which is the application I use for RSS feeds.]

