How to run DB2 export command in shell
There are three (well, actually four...) ways to execute export in DB2.

There is the db2export API (.sh in Unix/Linux, .exe in Windows). This can be executed from anything that understands command shell.

There is the export command to the db2 command. This can be run from a DB2 interactive session, or from the command shell.

There is also the export command through the ADMIN_CMD stored procedure. This allows you to invoke the export from a stored procedure which is accessable through anything that can execute SQL against DB2. This is probably the option you are looking for if you want to do export via SQL through another tool.

There is also the db2move utility which can perform an export, but that is done via command shell as well.