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Replace each `@wordpress user_login@` by the user posts page link in your posts contents.

Author:Benjamin Niess (profile at wordpress.org)
WordPress version required:3.1
WordPress version tested:4.2
Plugin version:1.3
Added to WordPress repository:10-07-2011
Last updated:22-04-2015
Warning! This plugin has not been updated in over 2 years. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
Rating, %:0
Rated by:0
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Total downloads:523
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Replace each @wordpress user_login@ by the user posts page link in your posts contents.

You only need to write something like

Your content here...I want to quote @the_login_of_my_friend@ ...." and the @the_login_of_my_friend@ string will be replaced by the author link if it exists