Crashdump leaves important information out as -f is 20MB by default

[sombrafam]

It's very common (if not the rule) in production environments logs with more than 20MB.
As its also not easy to ask customer to check the size of those files, before running the tool,
and them calling it with '-f <right_size_of_the_file_I_want>', it would be nice at least that -f would
tail the logs and send at least the last 20MB of information.