Baslinux mailing list

["Anthony J. Albert" <albert AT polaris.umpi.maine.edu>]

On 20 Feb 2004 at 9:53, Nguyen The Luan wrote:
>Hi All
>In Linux OS, we have 2 spaces: user space and kernel space.
>User space tasks has lower priviledges and priority than kernel space tasks.
>But kernel tasks are not able to get input from user, printf, read/write
>files...

Actually, kernel tasks are able to do these things - they just normally 
don't, with the exception of read/write files.

>So My question is:
>How can we make our user space tasks have priviledges and priority like
>kernel task.
>It means that our user space tasks not only communicate with users but also 
>do anything that kernel tasks can do.
>In other words, How to change Linux system from multiuser, multitasking to
>single user multitasking system.
>
>Best regards
>Nguyen

For the most part, there is never a need to do this.  The Unix design 
is such that, for the tasks that the user needs to do that are in 
"kernel space", there's a call to the kernel.   This is so that user-
space tasks which misbehave don't bring the whole system down - the 
kernel has a chance to force the process to exit.

I would recommend looking for a good book on operating system design, 
if you'd like more detail on why having kernel space and user space 
separate is a "good thing".

You can change to a single-user system, though, if you really want to.  
Most Linux allow you to set the runlevel, usually in /etc/inittab .  
Editing the line:
        id:3:initdefault:
to have an "S" or a "1" instead of a "3" will likely bring your system 
up in single-user mode, after rebooting.  

Don't know if everything will work, though, as many programs are only 
set to run at certain bootlevels.

Hope this is helpful,
Anthony Albert
===========================================================
Anthony J. Albert                     albert AT umpi.maine.edu
Systems and Software Support Specialist          Postmaster
Computer Services - University of Maine, Presque Isle
        "This is only temporary, unless it works."
                        --- Red Green