removing speakup from memory?

John G. Heim jheim at math.wisc.edu
Sun Jan 25 03:20:52 UTC 2015


Practically every service runs as a different user so one service cannot 
be used to attack another service.


On 01/24/2015 06:36 PM, 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
>
>
> 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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>>>
>>
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