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Attempts activation of plugin in a “sandbox” and redirects on success.
A plugin that is already activated will not attempt to be activated
again.The way it works is by setting the redirection to the error before
trying to include the plugin file. If the plugin fails, then the
redirection will not be overwritten with the success message. Also,
the options will not be updated and the activation hook will not be
called on plugin error.It should be noted that in no way the below code will actually prevent
errors within the file. The code should not be used elsewhere to
replicate the “sandbox”, which uses redirection to work.If any errors are found or text is outputted, then it will be captured
to ensure that the success redirection will update the error
redirection.
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solved explanation for activate_plugin function in wordpress core