Shell

http://bash.cyberciti.biz/guide/Perform_arithmetic_operations

http://www.oracle.com/technetwork/database/focus-areas/manageability/sqlmonitor-084401.html

http://www.eygle.com/archives/2004/10/howto_capture_problem_sql.html

http://space.itpub.net/28985005/viewspace-764378

http://www.itpub.net/forum.php?mod=viewthread&tid=181450