Date: Tue, 19 Apr 2005 16:32:37 -0400 From: Bill Moran <wmoran@potentialtech.com> To: Chuck Swiger <cswiger@mac.com> Cc: freebsd-stable@freebsd.org Subject: Re: Newbie Question About System Update Message-ID: <20050419163237.76a99373.wmoran@potentialtech.com> In-Reply-To: <42655B8E.5020603@mac.com> References: <426447F8.5090209@charter.net> <200504191317.j3JDH76H001458@drjekyll.mkbuelow.net> <20050419120053.6ad17df1.wmoran@potentialtech.com> <42655B8E.5020603@mac.com>
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Chuck Swiger <cswiger@mac.com> wrote: > Bill Moran wrote: > > The system can not replace programs that are in use, > > This is generally not the case. Unix lets you continue to access a file after > it has been deleted, so long as the process hangs on to a file descriptor. > This lets you replace programs in use, without running into the same problems > that platforms like Windows have. What you say?: bash-2.05b$ su Password: bolivia# cp /usr/sbin/cron /home/wmoran/. bolivia# cp /home/wmoran/cron /usr/sbin/. cp: /usr/sbin/./cron: Text file busy bolivia# Notice that /usr/sbin/cron is in use (because my system is running normally) I can copy _from_ that file, but I can not overwrite it. Apparenlty, nobody who is claiming this has _tried_ it. Try it yourself and see. You can _not_ replace programs that have their Text section in use (i.e. the code) because the demand pager has that area of the file locked. -- Bill Moran Potential Technologies http://www.potentialtech.com
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