For all content types in drupal

for_all_content_types_in_drupal.sh

#!/bin/bash                                                                                                                                    
drush sqlq "select type from node_type" | while read content_type;
do
   echo "Changing comment settings for $content_type"
   drush vset comment_default_mode_$content_type 0
   drush vset comment_default_per_page_$content_type 50
   drush vset comment_$content_type 2
   drush vset comment_form_location_$content_type 1
   drush vset comment_preview_$content_type 0
   drush vset comment_subject_field_$content_type 0
   # or do whatever with individual element of the array
done

Great job Gokul. Tested and worked well. I am sure, it will save lot of time especially when there are many content types. People can take cue from this script and can expand it to do many other such time taking things.