removing speakup from memory?

Joel Roth joelz at
Sun Jan 25 01:24:01 UTC 2015

On Sat, Jan 24, 2015 at 07:36:55PM -0500, Karen Lewellen wrote:
> wait.
> why would the system create elements tied to those not actually using the
> system?
> Forgive my lack of information here, but would that not be a security risk?
> If they were not created by me, who would create them?
> I have no means for typing that command, but I am curious about the concept.
> Karen

Different users can own their own files and directories
That is a key part of the Unix security model.

The operating system needs some user IDs of its own for the
processes it runs, for example to deliver mail
or respond to requests for web pages.

So, when you look in any /etc/passwd, you will see users
that belong to specific services that are installed
by default on your system. 

For security, many of the user accounts, such as 'mail' and
'nobody' prohibit the user to log in, no access by password.  

The concepts of users, groups, directories, subdirectories,
file ownership and permissions are innovations in computer
science that have stood the test of time. It starts simple,
and there are many subtleties. Even if you don't uses these
facilities deliberately, in order to be able to administer
your system, it is helpful to be minimally familiar with the
basic model.

Up to now I've found time invested very rewarding, and
there are excellent written tutorials to get started.

This learning will also go with you, if you change to
another unixlike operating system. 

Wish you happy exploring!


> On Sat, 24 Jan 2015, John G. Heim wrote:
> >Multi-user just means that each process  is owned by a user.  Some user ID
> >is tied to each process. Most of the processes are owned by users you
> >probably didn't create directly.   Examine the /etc/passwd file to see all
> >the users on your system.
> >
> >
> >On 01/24/2015 01:36 PM, Karen Lewellen wrote:
> >> Hi,
> >> Why would I have a multi user system?
> >> Oh wait I might know the answer to this one.
> >> no.  this box was built for me, I have an admin password, and I am the
> >> only user.  Something I have done once from the computer itself.  No ssh
> >> this time, I have no idea yet if the debian configuration on the machine
> >> even supports dsl.
> >> I will be turning it on to find out.
> >> I will want to turn it off again  when I am through, so thanks for all
> >> the  prospects.
> >> While Halt seems  like the most fun, better to just try shutdown -h.
> >> Thanks,
> >> Karen
> >>
> >>
> >> On Sat, 24 Jan 2015, Tim Chase wrote:
> >>
> >>>  On January 24, 2015, Karen Lewellen wrote:
> >>> >  what is the keystroke  for leaving Linux basically to shut down the
> >>> >  computer?
> >>> >  Unlike DOS, i understand you cannot just turn off the machine.
> >>> >  Depending on how new the computer is, you can usually just hit the
> >>>  power button to initiate a shutdown (as opposed to holding it in for
> >>>  3-5 seconds which does a hard power-off).  The press (rather than
> >>>  press-and-hold) sends a shutdown signal to the operating system.
> >>> >  If you want to initiate it from the command-line or over SSH, you
> >>can
> >>>  usually use one of "halt", "reboot", or "shutdown".  You might have
> >>>  to prefix it with "sudo" because on a multi-user system, it would be
> >>>  rude to allow any old user to reboot it out from under other users.
> >>>  I usually use "halt" to power down the machine, and "reboot" to,
> >>>  well, reboot (that's rare).  The "shutdown" command allows for
> >>>  additional options like sending messages to users that are logged in,
> >>>  deferring the shutdown for a period of time, etc.
> >>> >  So those are the graceful ways to shut down.
> >>> >  That said, if you're running a modern vintage of Linux, it should
> >>be
> >>>  fairly robust to handling abrupt power-offs.  Mostly it boils down to
> >>>  things that your software thinks has been written to the drive but
> >>>  hasn't actually made it to the drive.  If you use a journaling
> >>>  file-system (unless you're running a REALLY old version of Linux or
> >>>  you intentionally chose EXT2 or a FAT partition type on installation,
> >>>  you've likely have a journaling file-system since it's been the
> >>>  default for years).  Also, if you have external drives like a USB
> >>>  drive, you'd want to make sure that either it's set to write
> >>>  synchronously or that you properly unmount it since it's usually a
> >>>  FAT file-system which can lose data.
> >>> >  And if you're booting off a live CD, doing all your work on the
> >>>  internet, and not actually saving anything locally?  Feel free to
> >>>  unceremoniously rip the cord from the wall since there's nothing that
> >>>  won't be restored on a fresh boot.  Though I still usually just do a
> >>>  regular shutdown out of habit. (grins)
> >>> >  -tim
> >>> > > > > >
> >>
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Joel Roth

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