WordPress core is something where you cannot create your own hooks.
Hooks in WordPress are created with these
apply_filters
apply_filters_ref_array
apply_filters_deprecated
do_action
do_action_ref_array
do_action_deprecated
The only thing you can do is to register your function to certain WordPress core hook. But where are these hooks?
You may expect these hooks in a function called activate_plugin.
File: wp-admin/includes/plugin.php
512: /**
513: * Attempts activation of plugin in a "sandbox" and redirects on success.
514: *
515: * A plugin that is already activated will not attempt to be activated again.
516: *
517: * The way it works is by setting the redirection to the error before trying to
518: * include the plugin file. If the plugin fails, then the redirection will not
519: * be overwritten with the success message. Also, the options will not be
520: * updated and the activation hook will not be called on plugin error.
521: *
522: * It should be noted that in no way the below code will actually prevent errors
523: * within the file. The code should not be used elsewhere to replicate the
524: * "sandbox", which uses redirection to work.
525: * {@source 13 1}
526: *
527: * If any errors are found or text is outputted, then it will be captured to
528: * ensure that the success redirection will update the error redirection.
529: *
530: * @since 2.5.0
531: *
532: * @param string $plugin Plugin path to main plugin file with plugin data.
533: * @param string $redirect Optional. URL to redirect to.
534: * @param bool $network_wide Optional. Whether to enable the plugin for all sites in the network
535: * or just the current site. Multisite only. Default false.
536: * @param bool $silent Optional. Whether to prevent calling activation hooks. Default false.
537: * @return WP_Error|null WP_Error on invalid file or null on success.
538: */
539: function activate_plugin( $plugin, $redirect = '', $network_wide = false, $silent = false ) {
Note there is a parameter @param bool $silent that is optional that will prevent calling activation hooks. By default it is set to false.
In that function at the moment, you can find hooks:
File: wp-admin/includes/plugin.php
563: if ( ! $silent ) {
564: /**
565: * Fires before a plugin is activated.
566: *
567: * If a plugin is silently activated (such as during an update),
568: * this hook does not fire.
569: *
570: * @since 2.9.0
571: *
572: * @param string $plugin Plugin path to main plugin file with plugin data.
573: * @param bool $network_wide Whether to enable the plugin for all sites in the network
574: * or just the current site. Multisite only. Default is false.
575: */
576: do_action( 'activate_plugin', $plugin, $network_wide );
One more...
File: wp-admin/includes/plugin.php
563: if ( ! $silent ) {
...
578: /**
579: * Fires as a specific plugin is being activated.
580: *
581: * This hook is the "activation" hook used internally by register_activation_hook().
582: * The dynamic portion of the hook name, `$plugin`, refers to the plugin basename.
583: *
584: * If a plugin is silently activated (such as during an update), this hook does not fire.
585: *
586: * @since 2.0.0
587: *
588: * @param bool $network_wide Whether to enable the plugin for all sites in the network
589: * or just the current site. Multisite only. Default is false.
590: */
591: do_action( "activate_{$plugin}", $network_wide );
And one you actually need...
File: wp-admin/includes/plugin.php
605: if ( ! $silent ) {
606: /**
607: * Fires after a plugin has been activated.
608: *
609: * If a plugin is silently activated (such as during an update),
610: * this hook does not fire.
611: *
612: * @since 2.9.0
613: *
614: * @param string $plugin Plugin path to main plugin file with plugin data.
615: * @param bool $network_wide Whether to enable the plugin for all sites in the network
616: * or just the current site. Multisite only. Default is false.
617: */
618: do_action( 'activated_plugin', $plugin, $network_wide );
I just searched for the hook generator functions such as do_action.
What you do plugin_install_action_links is a filer type of hook. Filter are typically there to replace certain things.
File: wp-admin/includes/class-wp-plugin-install-list-table.php
519: /**
520: * Filters the install action links for a plugin.
521: *
522: * @since 2.7.0
523: *
524: * @param array $action_links An array of plugin action hyperlinks. Defaults are links to Details and Install Now.
525: * @param array $plugin The plugin currently being listed.
526: */
527: $action_links = apply_filters( 'plugin_install_action_links', $action_links, $plugin );
Using "plugin_install_action_links" I can control the action links through php, but what is the ajax equivelent (if there is one)?
There is a file called admin-ajax.php. You can examine this file, and you can use hooks to do your specific things, but there are no filters defined at the moment in admin-ajax.php.
