Linux and all UNIX-like systems is multi user by default.
The system creates only UIDs that are needed by the system and no
security risk at all.
On a standard installation only your own UID is created and optionally
one for root and then all system users of which are set to /bin/nologin
or something similar.
All these UIDs is required for the system to run properly.
This is how UNIX is designed.
Examples of system UIDs are: bin, daemon etc etc.
To shutdown a linux box 'shutdown -h now' is the correct way.
That said I never shutdown a Linux box because it's designed to be
running 24/7 smile.
On 25/01/2015 01:36, 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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