Where is the Oracle Database alert log located ?

This is something I keep forgetting so I think that I may as well add it here.

On my Linux system the alert log is located in $ORACLE_HOME/admin/$ORACLE_SID/bdump while the exact same path -- with "\" instead of "/" -- is used for Windows.

The directory where the alert.log found is determined by the background_dump_dest initialization parameter: So the ultimate way to find it is by issuing an SQL command like :

select value 
    from v$parameter 
    where name = 'background_dump_dest';

Needless to say that the alert.log's name is alert.log and that it is a simple text file that can be opened using any text editor and that you can delete it or shrink it online.