On Mon, Nov 11, 2002 at 09:57:16AM -0500, sean finney wrote: > On Mon, Nov 11, 2002 at 11:56:02AM +0200, Shaul Karl wrote: > > Basically, when one removes a binary file from a UNIX file system, it > > is gone - no matter if this binary is currently in use. Therefore, > > i don't think that's necessarily true. i believe the way it works is > that a file is not 'gone' (in the sense of fs de-allocation) until there > are no more references to it. so for example, i think if you open a > file for reading, and then immediately remove the file, you should still > be able to read the entire file, even if it's over a page in size. > you could verify this with a simple c-program or perl script where you > open the file, then rm it via system(), and then read the data. > > now i could be wrong (and feel free to correct me if i am), but i think > executing the file also counts as a reference to it in some way, so when > you delete the file and/or overwrite it with an upgrade, if the program > is running in memory it should be just fine and should be able to load in > pages that weren't already in memory, but as soon as it exits the file > is 'gone'. in the meantime that the program is running, subsequent > calls to exec/read that file will get the new file (or fail if it was > simply removed).
You are correct. This is how it's possible for distributions like Debian to upgrade running programs. http://www.debian.org/doc/FAQ/ch-pkgtools.en.html#s-updaterunning (although it doesn't go into much detail ...) -- Colin Watson [[EMAIL PROTECTED]] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
