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Re: How do you use the "at" command?

Followups directed to: comp.os.linux.misc

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On Wednesday 01 February 2012 00:46, Darren Salt conveyed the following 
to comp.os.linux.misc...

> I demand that Aragorn may or may not have written...
> 
>> The workaround is to, instead of using an initrd/initrams - for
>> instance if you roll your own kernels - use a pre-init script which
>> mounts "/usr" (and whatever else you would like it to mount) and then
>> calls the actual init
>> via exec, like so...  (Note: location of GNU Bash and init adapted to
>> the future scenario and using ext4.)
> 
>>    #!/usr/bin/bash
>>    mount -r -t ext4 /dev/sda2 /usr
>>    exec /usr/bin/init
> 
> Slight issue: you need to have bash (or, better, dash) in /usr with
> the real /usr not mounted. I'd be more likely to dpkg-divert some
> files and add symlinks so that what's necessary to allow /usr to be
> mounted is available and will be updated when packages are updated.

Yes, I realized my mistake, which is why I posted a follow-up to my own 
post. ;-)

> Also, assuming that /etc/fstab isn't going to be moved, you can omit
> the type and partition name.

True.  But the commands would have to be issued like that if they were 
being issued from within the initramfs.  I guess I just typed them up 
here as such. ;-)

> devtmpfs ensures presence of the device nodes, so no problem there.
> 
> Of course, it's better to have udev work without needing this or not
> to bother with separate /usr – but then you lose fast fsck of your
> nice small root partition. (Not a big loss, but still...)

I prefer having a separate and read-only mounted "/usr" myself.

>> You then store this script in, say, "/sbin", and then you invoke it
>> via the kernel's parameter line in the bootloader - for LILO, that's
>> on the "append=" line - like so...
>>    append="init=/sbin/pre-init.sh"
> 
> Would work, subject to binaries actually being available.

Yes, and that appears to be the problem.  As I have stated in my 
correcting follow-up, it would indeed appear that the binaries are no 
longer available without that "/usr" is already mounted, barring the 
scenario where you have an initramfs with busybox or a similar small 
toolbox.

>> But of course, that too will break if "/sbin" is going to be a
>> symbolic link to "/usr/sbin".  So they are really pushing the
>> initramfs route.
> 
> Or at least no separate /usr. udev needs to be fixed... :-|

According to their statements on opendesktop.org - see my reply to 
Robert Heller - they are definitely not planning on that, and they are 
instead advocating having everything under "/usr".

>> (I hate those things. :p)
> 
> Me too. (Except on installation media.)

Well, of course.  Installation media and live CDs/DVDs are a totally 
different beast altogether.

> [snip]
>> But either way, I expect that ext4 too is soon going to be deprecated
>> in favor of btrfs,
> 
> I doubt very much that ext4 will disappear. I do expect ext2 and ext3
> to disappear completely (in the kernel) into ext4, though.

I didn't mean to say that it would disappear, but rather that 
distributions will be pushing btrfs - some already are doing just that - 
as the "default", and given how many people simply accept the defaults 
upon installation, the percentage of ext4 systems is most likely about 
to thin out in the near future.

-- 
= Aragorn =
(registered GNU/Linux user #223157)

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Thread

How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 10:16 -0800
  Re: How do you use the "at" command? Lew Pitcher <lpitcher@teksavvy.com> - 2012-01-27 13:43 -0500
    Re: How do you use the "at" command? Lew Pitcher <lpitcher@teksavvy.com> - 2012-01-27 13:45 -0500
      Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-27 15:34 -0600
        Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 22:41 -0800
          Re: How do you use the "at" command? Loki Harfagr <l0k1@thedarkdesign.free.fr.INVALID> - 2012-01-28 10:27 +0000
            Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-01-28 19:05 +0100
              Re: How do you use the "at" command? Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2012-01-28 10:26 -0800
              Re: How do you use the "at" command? Loki Harfagr <l0k1@thedarkdesign.free.fr.INVALID> - 2012-01-30 08:51 +0000
                Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-01-31 03:16 +0100
                Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-02-01 00:24 +0100
                Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-31 17:55 -0600
                Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-02-01 02:01 +0100
                Re: How do you use the "at" command? "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2012-01-31 21:36 -0500
                Re: How do you use the "at" command? "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2012-01-31 21:25 -0500
                Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-02-01 04:57 +0100
                Re: How do you use the "at" command? Darren Salt <news@youmustbejoking.demon.cu.invalid> - 2012-01-31 23:46 +0000
                Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-02-01 02:12 +0100
  Re: How do you use the "at" command? Richard Kettlewell <rjk@greenend.org.uk> - 2012-01-27 19:10 +0000
    Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 11:17 -0800
      Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-27 15:34 -0600
  Re: How do you use the "at" command? unruh <unruh@invalid.ca> - 2012-01-27 20:26 +0000
    Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 22:51 -0800
  Re: How do you use the "at" command? Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2012-01-27 12:23 -0800
    Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-27 15:35 -0600
      Re: How do you use the "at" command? Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2012-01-27 17:22 -0800
        Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-27 20:25 -0600
          Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 22:49 -0800
            Re: How do you use the "at" command? Bit Twister <BitTwister@mouse-potato.com> - 2012-01-28 07:16 +0000
              Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 23:57 -0800
        Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 22:49 -0800
          Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-28 06:07 -0600
            Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-28 13:32 -0800
              Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-28 22:28 -0600
                Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-28 22:50 -0800
                Re: How do you use the "at" command? Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2012-01-28 23:35 -0800
                Re: How do you use the "at" command? unruh <unruh@invalid.ca> - 2012-01-29 18:46 +0000
                Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-29 12:03 -0800
                Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-29 15:38 -0600
                Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-29 16:58 -0800
                Re: How do you use the "at" command? unruh <unruh@invalid.ca> - 2012-01-30 01:36 +0000
                Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-01-30 03:07 +0100
                Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-29 19:21 -0800
                Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-29 19:17 -0800
                Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-29 11:48 -0800
                Re: How do you use the "at" command? Robert Heller <heller@deepsoft.com> - 2012-01-29 07:35 -0600
                Re: How do you use the "at" command? Aragorn <stryder@telenet.be.invalid> - 2012-01-29 20:40 +0100
          Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-02-03 13:25 -0800
      Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 22:45 -0800
    Re: How do you use the "at" command? Todd <Todd@invalid.invalid> - 2012-01-27 22:42 -0800

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