On Monday 06 September 2010, Keith Edmunds wrote: > On Mon, 6 Sep 2010 17:24:42 +0100, [email protected] said: > > That's as I understand it, but there is apparently a company out there > > somewhere that can patch a running kernel for Enterprise customers. > > Well, actually, anyone can do that for any customer, although I wouldn't > recommend it. > > Previous posters are right: the currently-running application will run > from memory. Some upgrades (eg, Apache under Debian) will restart the > daemon as part of the upgrade. > > -- > Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 > Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ > How to Report Bugs Effectively: http://bit.ly/4sACa As I recall.... Normal user space executable files.... An running executable (ELF executable at any rate [ "file /bin/cat" to see] ) holds its executable file open and pages in from this executable file (when read-only or "clean" pages are required). The executable pages OUT (i.e. pages that have changed - "dirty") to the swap file - from where they are paged back in if required. Thus - (and I have seen this happen) if you _overwrite_ a running programs' executable file it will more than likely crash! BUT.... The standard technique used for installing a new executable file (Used to be - at any rate) is to first of all delete (aka "rm") the existing file before creating the new one. This invokes an ancient bit of UNIX/Linux fundamentals ... a file is NOT actually deleted until no executables have it open. - thus the running program still has access to the already open ORIGINAL executable file - so pages in happilly and keeps running. But the original file is no longer visible in the file-system (but it still occupies an inode). The updating software then creates a NEW executable (the updated version) and any new invocations of the executable file lo & behold will now run the updated version. Thus you can "update" a running executable file.
As for Windows - you must be joking! -- Andy Paterson -- Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
