MediaWiki developers create the MediaWiki software used in various Wikimedia Foundation projects.

User Maintenance

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  Decide which user to examine
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  And see that user's information, preferences, etc...
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  Change a user's permissions (Steward function on Wikimedia Foundation wikis, Bureaucrat elsewhere)
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  Modifying the permissions of a global group

The Interwiki Interface

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  Viewing the interwiki map
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  ...and adding an entry.
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  Finished!

Other tools

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  Locking the database for some slight construction work.
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  Uses the +import privilege, allows you to bring articles and edit history to a different wiki.
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  View the absolute path to an image, typically unlocked for all users.
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  Show files matching a specific mask.
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  The infamous AskSQL interface.