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Re: Re: Somethings about libraries..

> But I suspect that there are mechanisms which prevent you from writing
> to a file, while it is being executed. If you have a.out open in gdb,
> gcc can't write to it.
> -Arun

Yes !! when a file is executing .. you can not edit it .. I have also
observed it while running server programs in background and then trying to
recompile their new version without stopping them ....


----- Original Message -----
From: "Arun Sharma" <arun@xxxxxxxxxxxxxxx>
To: <deepakyadav@xxxxxxxxx>
Cc: <linux-india-programmers@xxxxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, November 21, 2000 10:56 PM
Subject: Re: Re: [LIP] Somethings about libraries..

> On Mon, Nov 20, 2000 at 11:05:00PM +0500, D ee p a K wrote:
> > >>  How can the kernel know that the new program is different from
> > >> the one it loaded just a short while ago.
> >
> > if the original code file is replaced by a new copy then a new inode
> > entry is created and the previous one remains until at least one
> > instance of it is executing.
> That's right. The old one stays. But the old guy doesn't stay in
> the vnode cache. If you look for "/home/user/a.out" in the vnode
> cache, you get the new version, rather than the old.
> > the question still remains that  how the process already running react
> > to new code. if  i manually open the file & copy the data to it.
> When you manually open and write to the executable, the kernel has a
> chance to update it's vnode cache. Remember, UNIX processes instantiate
> their pages lazily. The pages which have been already instantiated, will
> point to old inodes and the ones which haven't been, will point to the
> new one.

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