Patrick O'Callaghan wrote: > > Until you reboot, some updates are not installed, they're just sitting > there in a disabled state. It's the reboot process that commits the > change. It is almost what happens on Fedora with preupgrade. But for Fedora this is only used to do huge changes to the system (at the Windows 2000 -> Windows XP level). Windows does it basically every time. > Although I haven't investigated it in detail, I suspect that this is > because of a fundamental design limitation of Windows. On Unix-like > systems a file can be deleted while still in use, and any processes that > haven't closed it just keep on using it with no problem. Windows doesn't > allow this, so the update can't actually install the new files > (including new executables) until every process using them has stopped. > The easiest way to do this is to reboot. > > OTOH on Unix the updated files (and executables) are completely > installed. Any existing processes that use them will at some point have > to be restarted (see the needs-restarting app already mentioned) but > that can be done as needed. > > The more you think about it, the smarter the Unix file access model > looks. Ken Thompson is a smart guy and the use of inodes to disconnect > directory entries from the files they refer to is one of the smartest > things he ever did :-) You are perfectly right. The Unix access model never has locked files. You can always delete them (and recreate them again with different content). It is trivial on Unix to update glibc and sshd while being connected remotely through ssh. The only disadvantage is that some programs could still use old version of the files, if they were already running during the upgrade. For example, if you upgrade the libjpeg to fix a vulnerability, you are not totally sure if your browser is still using the old one. But you can discover these cases easily with a simple "lsof -n|grep deleted". -- Roberto Ragusa mail at robertoragusa.it -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
