netbox-community-netbox/netbox/templates/dcim/inc/device_table.html

{% extends 'utilities/obj_table.html' %}

{% block extra_actions %}
    {% if perms.dcim.add_interface %}
        <button type="submit" name="_edit" formaction="{% url 'dcim:device_bulk_add_interface' %}" class="btn btn-primary btn-sm">
            <span class="glyphicon glyphicon-plus" aria-hidden="true"></span> Add Interfaces
        </button>
    {% endif %}
{% endblock %}