"aptitude update" as cronjob, customize the cron-mail-output

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http://askubuntu.com – I have set up aptitude update as cronjob for root and sending the mail to my normal user account. What I want to have now, is that all the output of aptitude is ommited and instead only a summarization of all packages that are new or could be updgraded. Also in case of errors, there should be a list of errorous repos/ppa and the corresponding errormessage. Is there a way to do such a cronjob, and where can I find informations about scripting such thing? (HowTos)