Source

File: wp-admin/includes/update.php

function update_right_now_message() {
	$theme_name = wp_get_theme();
	if ( current_user_can( 'switch_themes' ) ) {
		$theme_name = sprintf( '<a href="themes.php">%1$s</a>', $theme_name );
	}

	$msg = '';

	if ( current_user_can( 'update_core' ) ) {
		$cur = get_preferred_from_update_core();

		if ( isset( $cur->response ) && 'upgrade' === $cur->response ) {
			$msg .= sprintf(
				'<a href="%s" class="button" aria-describedby="wp-version">%s</a> ',
				network_admin_url( 'update-core.php' ),
				/* translators: %s: WordPress version number, or 'Latest' string. */
				sprintf( __( 'Update to %s' ), $cur->current ? $cur->current : __( 'Latest' ) )
			);
		}
	}

	/* translators: 1: Version number, 2: Theme name. */
	$content = __( 'WordPress %1$s running %2$s theme.' );

	/**
	 * Filters the text displayed in the 'At a Glance' dashboard widget.
	 *
	 * Prior to 3.8.0, the widget was named 'Right Now'.
	 *
	 * @since 4.4.0
	 *
	 * @param string $content Default text.
	 */
	$content = apply_filters( 'update_right_now_text', $content );

	$msg .= sprintf( '<span id="wp-version">' . $content . '</span>', get_bloginfo( 'version', 'display' ), $theme_name );

	echo "<p id='wp-version-message'>$msg</p>";
}