in reply to what are the commonly used modules in perl?
As you can see from the other responses, it depends on the problems you tend to need to solve. Having said that, my list of "indispensible modules" is: Spreadsheet::ParseExcel, Spreadsheet::WriteExcel, DBI, DBD::ODBC, DBD::Oracle, and DBD::SQLite. There are dozens of others that I also like to use, but since I do a lot of data spelunking and generating reports for users, these are the ones that I use in most of my projects.
When your only tool is a hammer, all problems look like your thumb.