What do you mean by "catch errors and exceptions"? That sort of phrase is typically interpreted to mean something like:

eval {
    &something_that_throws_exceptions
};
if ( $@ ) {
    &exception_handler
}
[download]

or even:

use Exception::Class::TCF;
try {
    &something_that_throws_exceptions
} catch 'Default' => \&exception_handler;
[download]

However, because you're also talking about log files, it sounds like you mean something else. Like how to parse a file? Regular expressions? Writing to files? It's impossible to tell. Maybe you have an example of some lines in the log, and some code you've written so far to show your intentions.