On 12/14/19 5:02 PM, Thomas Deutschmann wrote: > > acct-* shouldn't mess with already *existing* users. So upgrade > experience shouldn't be affected...
Even on upgrades, pkg_postinst() in acct-user.eclass will update the home directory, shell, groups, and comment field. Without more information, all I can say is that there's probably a better way to do whatever these users are doing that doesn't involve modifying a system user. But regardless, Michał's answer is the right one if you decide that you do want to modify it.
