[9fans] items in /bin with leading underscores

[9fans] items in /bin with leading underscores

[Heiko Dudzus]

In /bin there exist two similar entries of executables: One with and
one without a leading underscore, e.g. /bin/touch and /bin/_touch.

They seem to have different sizes.

What is about it? How do they differ?

Re: [9fans] items in /bin with leading underscores

[Christian Grothaus]

> In /bin there exist two similar entries of executables: One with and
> one without a leading underscore, e.g. /bin/touch and /bin/_touch.
> 
> They seem to have different sizes.
> 
> What is about it? How do they differ?

The ones with the leading underscores are created when you
replica/pull from the sources: when there's a new version of /bin/x,
replica/pull first executes 'mv /bin/x /bin/_x' so that you can switch
back to the old version in case there are problems with the new one.

Christian

Re: [9fans] items in /bin with leading underscores

[Skip Tavakkolian]

> What is about it? How do they differ?

replica/pull moves the old versions out of the way by changing
their names (they could be running), before copying new ones over.

Re: [9fans] items in /bin with leading underscores

[Heiko Dudzus]

Skip Tavakkolian wrote:
> replica/pull moves the old versions out of the way by changing
> their names (they could be running), before copying new ones over.

Ahh. Thanks to both of you.

Re: [9fans] items in /bin with leading underscores

[C H Forsyth]

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it only does it once, and the next run will discard the
file saved by the first run, so if you've got long-running systems
(and since you're running plan 9, they often are long-running systems
once they are running), you still need to worry about it.
it's a good question whether the file servers should.

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From: Heiko Dudzus <heiko.dudzus@gmx.de>
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] items in /bin with leading underscores
Date: Sat, 6 Nov 2004 20:30:29 +0100
Message-ID: <20041106193029.GA2984@SDF.LONESTAR.ORG>

Skip Tavakkolian wrote:
> replica/pull moves the old versions out of the way by changing
> their names (they could be running), before copying new ones over.

Ahh. Thanks to both of you.

Re: [9fans] items in /bin with leading underscores

[Heiko Dudzus]

C H Forsyth wrote:
> Skip Tavakkolian wrote:
> > replica/pull moves the old versions out of the way by changing
> > their names (they could be running), before copying new ones over.
>
> it only does it once, and the next run will discard the
> file saved by the first run, so if you've got long-running systems
> (and since you're running plan 9, they often are long-running systems
> once they are running), you still need to worry about it.
> it's a good question whether the file servers should.

Isn't a complete image of the running binaries in the memory (of the
machine where it runs on). I ever thought a running program was
independent of its file. 

(I'm not sure if I really should take part of this discussion, because it goes
beyond my knowledge and understanding ;-/

Re: [9fans] items in /bin with leading underscores

[C H Forsyth]

>>I ever thought a running program was independent of its file. 

not in general, because the kernel reads on demand from the file when a page
is required and not already in the image cache.