Plugin hook that only fires when a new post is published? [duplicate]

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• Execute function when post is published 1 answer

I wrote a plugin for my site which posts an update on my forum whenever a new post is published. I'm using the "publish_post" and "publish_future_post" actions. The problem is, these actions also trigger whenever a post is updated. I only want the action to trigger if a new post is published, not if older posts are updated. I don't see any actions that do this in the WP reference. Is there another way to accomplish what I'm trying to do?