Linux Administration on zSeries and S/390 Systems?

>  how to boot or run without the X or GUI mode?
As root, edit /etc/inittab
id:5:defaults:   ===> id:3:defaults:

Runlevel 3 is the text mode.

For Linux/Unix server, running X or GUI is not required and it will bring in some security concern since
X11 has the buffer overflow issue from time to time.
If you are familiar with command line administration, then you definitely no need to run X on server.
It consumes more resource and raise more security holes.

By the way, /etc/inittab is for boot up default runlevel.
If you want to change from current runlevel 5 (GUI) to runlevel 3 (text), then as root, type
init 3

Ok, great. I got it.

But one more question here if I can. How do MOST Linux Administrators run their Mainframes? Do they run it in Runlevel:3? In other words, which type of mode is usually the most secure and mostly used on Mainframes running on Linux?

Thanks

Most secure mode? Single user mode is the most secure mode. :-)
Anyway, for most of Linux distros, runlevel 3 is mostly used on Mainframes.

Thanks... to everyone.

One last question. What messages or codes that are displayed on each console emulation application (usually running Windows) that are transmitted from the Linux Mainframes? I one time took a tour of this datacenter and they had this console emulator (TN5250 or TN3270) and it had the Date/Time listed and plus the messages or codes along with it constantly logging those messages on the consoles.

Is there like a screenshot to show me? What do they relaly mean? Please provide me with a link on where I can read upon this informationi please.

 

In /etc/syslog.conf, there is
kern.*       /dev/console    (this line  may be commented out)

Console emulator just take your console (or the monitor hook on the Linux box) output and pipe it to
the console emulator's monitor through serial port.
The messages you saw are configured by /etc/sysconfig.conf.

Please do
man  syslog.conf
for more information.

Uhm, they looked liked this below:

21:05 IW05578

> 21:05 IW05578
This message is showed by the console emulator. (date and hostname or port name)
But the rest of console messages is configure in /etc/syslog.conf

Ok now I got it. Because when I saw the console, it continuesly kept logging codes or messages from the Linux z/VM Mainframe.

Is their any website that I can go on and read further on this?

I have the TN3270 emulator. I was trying to ask for like a screenshot of those messages on a emulator somewhere on a website. If someone can, then please let me know. Thanks.

I found one here:
http://www.bsp-gmbh.com/turnkey/cookbook/opmvs.html

I saw something like this on a datacenter but the codes were gathered from a z/VM Linux system.