Porticron is a script for automating running emerge --sync (or eix-sync).

It mails a report to root about what files need updating and with eix-sync enabled it also includes the difference between the old and new sync in the report.

A small configuration file (/etc/conf.d/porticron) allows you to set some settings related to it's use.

** Synching **

If /usr/portage is writeable and SYNC="yes" is in the config file, it will try to run emerge --sync.
If eix is installed on the system and EIXSYNC="yes" is in the config file, it will use eix-sync for updateing.

If you share a /usr/portage directory among multiple machines, you can either mount it read only or set SYNC="no" on the clients.

** EMERGE_DEFAULT_OPTS **

The following EMERGE_DEFAULT_OPTS options is detected:
--with-bdeps and --with-bdeps=y
both makes it use --with-bdeps=y as an option.

--reinstall changed-use
If this option is detected (only --reinstall is checked for) it will be used instead of --newuse.

--usepkg
If usepkg is detected it will be used for creating the list of updated packages.

The other options used is : --pretend --changelog --update --deep --quiet

Setting EDO="no" in the config file will disable this behavior and the program will use: --usepkg --newuse

** TimeStamp System **

For people using a shared NFS mounted /usr/portage it has support for a TIMESTAMP system, each client can create a file in /usr/portage/distfiles/timestamp and the machine that performs sync will erase any file in that directory, so you can use it in a cron job to detect when it's time to run the update on the clients.