Exporting settings in a code with Features / Strongarm - how to detect right variables - config ones Many modules does not support Features, so I need Strongarm module to export config in the code. But in situation where i have many contrib modules, it seems tedious work. not all variables are named after module.

More important, how can I know which variables are used for settings, as I noticed some vars are not used for settings but may be user/module specific, and I need to aviod them.

I want to Strongarm only variables that have to do something with the config.

Is it done by researching modules one by one ? What are your experiences (It would be nice if I could filter variables that are used only in config :) )
Unfortunately, the Drupal variables table doesn't provide any distinction between variables used for configuration (e.g., whether anonymous pages should be cached) and variables used to store transient values (e.g., date cron was last run, which tabs are currently active in the UI), so there's no automatic way to do this.  (Fortunately, it looks like Drupal 8's configuration management system will handle this better.)

I typically export and update Features modules from the command line using Drush.  I've been using the following Unix shell script to list Features Components which haven't yet been exported to any feature — the script filters out Features Components I know I don't want in my Features modules:

drush fc % --not-exported \
    | grep -v '^ dependencies:' \
    | grep -v '^ user_permission:access devel information' \
    | grep -v '^ user_permission:execute php code' \
    | grep -v '^ user_permission:switch users' \
    | grep -v '^ uuid_node:' \
    | grep -v '^ variable:additional_settings__active_tab_' \
    | grep -v '^ variable:cron_key' \
    | grep -v '^ variable:cron_last' \
    | grep -v '^ variable:ctools_last_cron' \
    | grep -v '^ variable:date_api_version' \
    | grep -v '^ variable:dev_mem' \
    | grep -v '^ variable:dev_timer' \
    | grep -v '^ variable:devel_api_url' \
    | grep -v '^ variable:devel_error_handlers' \
    | grep -v '^ variable:devel_execution' \
    | grep -v '^ variable:devel_krumo_skin' \
    | grep -v '^ variable:devel_page_alter' \
    | grep -v '^ variable:devel_query_display' \
    | grep -v '^ variable:devel_query_sort' \
    | grep -v '^ variable:devel_raw_names' \
    | grep -v '^ variable:devel_rebuild_theme_registry' \
    | grep -v '^ variable:devel_redirect_page' \
    | grep -v '^ variable:devel_use_uncompressed_jquery' \
    | grep -v '^ variable:devel_xhprof_directory' \
    | grep -v '^ variable:devel_xhprof_enabled' \
    | grep -v '^ variable:devel_xhprof_url' \
    | grep -v '^ variable:drupal_css_cache_files' \
    | grep -v '^ variable:drupal_http_request_fails' \
    | grep -v '^ variable:drupal_js_cache_files' \
    | grep -v '^ variable:drupal_private_key' \
    | grep -v '^ variable:entityreference:base-tables' \
    | grep -v '^ variable:features_codecache' \
    | grep -v '^ variable:features_ignored_orphans' \
    | grep -v '^ variable:features_semaphore' \
    | grep -v '^ variable:install_profile' \
    | grep -v '^ variable:install_task' \
    | grep -v '^ variable:install_time' \
    | grep -v '^ variable:mimemail_key' \
    | grep -v '^ variable:prod_check_module_list_lastrun' \
    | grep -v '^ variable:simplenews_last_cron' \
    | grep -v '^ variable:simplenews_last_sent' \
    | grep -v '^ variable:simplenews_private_key' \
    | grep -v '^ variable:simplenews_source_cache' \
    | grep -v '^ variable:update_last_check' \
    | grep -v '^ variable:xmlsitemap_generated_last' \
    | grep -v '^ variable:xmlsitemap_rebuild_needed' \
    | grep -v '^ variable:xmlsitemap_regenerate_needed'