The documentation for each plugin usually includes specific installation instructions for that plugin, but below we document the various available options:

Core Elasticsearch pluginsedit

Core Elasticsearch plugins can be installed as follows:

sudo bin/plugin install [plugin_name]

For instance, to install the core ICU plugin, just run the following command:

sudo bin/plugin install analysis-icu

This command will install the version of the plugin that matches your Elasticsearch version.

Community and non-core pluginsedit

Non-core plugins provided by Elasticsearch, or plugins provided by the community, can be installed from download.elastic.co, from Maven (Central and Sonatype), or from GitHub. In this case, the command is as follows:

sudo bin/plugin install [org]/[user|component]/[version]

For instance, to install the Kopf plugin from GitHub, run one of the following commands:

sudo bin/plugin install lmenezes/elasticsearch-kopf 
sudo bin/plugin install lmenezes/elasticsearch-kopf/2.x 

When installing from Maven Central/Sonatype, [org] should be replaced by the artifact groupId, and [user|component] by the artifactId:

sudo bin/plugin install groupId/artifactId/version