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From Tony Sanders <sand...@bsdi.com>
Subject Re: Novel way to kill Apache
Date Thu, 06 Feb 1997 23:23:13 GMT
Ben Laurie wrote:
> > > If you build a program under Irix while it is running, it changes the code
of
> > > the running program, usually resulting in a crash! This comes as a big surprise
Dean wrote:
> > It can happen on a lot of unixes in my experience.  In fact, all the ones
> > that let you scribble into a running executable (i.e. they don't lock the
> > executables).  That includes BSD*, linux, solaris, and IRIX.  But some of
> > them probably ship with ld that unlink the old executable and create a new
> > inode for the new one, (or gnu ld does this, I don't remember). 
> > 
> > Dynix/ptx won't let you rm a running executable, you have to rename it. 
> > That's the only oddball I've ever worked with though.

All BSD derived Uni that I have worked with (Sun OS, Convex OS,
BSD/OS) lock the on disk executable and refuse to allow you to
overwrite it.  Therefore, to install a new binary while it's running
you must remove the old one, leaving the old inode unlinked but
still around until either the process exists or the system crashes
and fsck cleans it up.

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