Contents:

chown raj:www-data sessions

debug.txt - contains debugging information; opened in overwrite mode ('>') per request
debug.log - contains debugging information; opened in append mode ('>>'); rotated using log_rotate.pl (count => 3)

deployment.sql - all query statements from application in production mode; rotated using log_rotate.pl (count => 3)
development.sql - all query statements from application in development mode; rotated using log_rotate.pl (count => 3)
today.sql - contains UPDATE/INSERT/DELETE statements from application in production mode; archived in /old daily using log_rotate.pl

file ownership:
development.sql	640 raj:raj/staff
debug.txt 		666 raj:raj/staff
debug.log 		666 raj:raj/staff
# where cron user is NOT a member of apache-user group:
deployment.sql	666 www-data:www-data
today.sql       644 www-data:www-data
# where cron user IS a member of apache-user group:
deployment.sql	660 www-data:www-data
today.sql       640 www-data:www-data

To truncate file in use:
  sudo cp new_msgs.log new_msgs.log.nn && sudo cat /dev/null > new_msgs.log
  sudo chown raj:raj new_msgs.log.nn