CentOS download is only server machine run at http://www.centos.org/download/ ? in other words cent os come in server only? if my live server is cent os 6 - is good install server in a VM like VMware PLAYER and Practice and try first locally after remotely to install eg Java/Tomcat or anything else?
The CentOS installer will ask you if you want to install the server or desktop version. That one download contains both the server and the desktop version with the graphical user interface. There is a second DVD installation disk that contains other stuff you will not need. So you do not need to download the second disk (I could not find it just now anyway). Just download DVD 1. For fastest speed, you may want to choose a mirror with a .edu extension.
http://isoredirect.centos.org/centos/6/isos/x86_64/CentOS-6.5-x86_64-bin-DVD1.iso
how can emulate SSH access in VM of cent os 6 server? Practicing on VM is the recommended Practice to handle a real live server?
That can get complicated depending on implementation. You should google for a current tutorial “How to install CentOS on VM with SSH Acess”. IT’s not an uncommon thing to do and there are TONS of good linux tutorials for just about every Distro out there.
if use centos6 in VM Command CLI - commands are the same as SSH on live server?
I have CentOS installed as a virtual machine using VirtualBox. My Windows 7 computer is the host and the virtual machines are the guest operating system. When I installed CentOS 6.5, openssh-server was installed by default if my memory is correct (with Ubuntu Server, you have to select to install openssh-server when installing the OS otherwise you will not be able to SSH into the server remotely). With CentOS, I downloaded puTTY to my host operating system and was able to connect to the CentOS virtual machine without any problems.
If you run the following command in your CentOS terminal you will see if openssh-server is installed:
rpm -qa | grep ssh
You should see something like this as output (your installed version number may be different):
openssh-server-5.3p1-94.el6.x86_64
So to answer your question, openssh-server should be installed by default when installing CentOS. You should be able to connect to your CentOS server remotely using a ssh client like puTTY.
I moved away from CentOS to focus my attention on learning Ubuntu as it is more user friendly than CentOS. CentOS is known for stability and that is why a lot of hosting companies use it for shared servers. Ubuntu tends to be a little more “bleeding edge” than CentOS, but all Linux distributions do not officially support new software for years after it is released, generally speaking. Bleeding edge would not be an appropriate term for not supporting new software for years. For example, as of March 2014 the only version of PHP in the repos of CentOS and Ubuntu was PHP 5.3 which was released in 2009. If you wanted to use PHP 5.4 or 5.5, you would have to find a package on a third-party repo or compile it yourself.
apt-get install php5
Installs PHP 5.5.9 on Ubuntu. (I just did it) My Debian 7 server is running 5.4, which was installed sometime at the end of last year. You’re probably thinking of the Ubuntu LAMP package. Those pre-packaged deals are always way behind.
You can always stay pretty up to date on PHP, MySQL, Apache, Ngnix, PostgreSQL, Python, and Perl on both the Fedora and Debian families without needing to do a make file.
No, I am not thinking of the LAMP package. As of three months ago PHP 5.3 was the only thing available in the official Ubuntu repository. Just in case you do not believe me, you can refer to these sources from Dec. 2013 and Feb. 2014 with people saying only 5.3 is to be found in the repo.
Feb. 2014: http://stackoverflow.com/questions/21714009/installing-php-5-5-8-in-ubuntu-12-04
Dec. 2013: http://phpave.com/upgrade-php-5-3-php-5-5-ubuntu-12-04-lts/
Ubuntu 14.04 LTS was released a month or so ago and I have not upgraded to it. It does appear that PHP 5.5.9 is available in the official Ubuntu repo (trusty) for the latest Ubuntu. That is new and I must say a welcome upgrade as the thought of being stuck at 5.3 was a real bummer. As of three months ago, Ubuntu’s support for PHP was years out of date, as was CentOS.
Perhaps you can check to see which version of Apache is available in the Ubuntu repo? For Ubuntu 12.04 LTS, it was Apache 2.2.x. Apache 2.4 was not an option, so I had to compile it myself on my home development server.
Hmmm… looks like you’re right. Debian also seems to stay a little better updated. Why choose Ubuntu over Debian for a server? I’ve been playing around with a Ubuntu server recently and trying to figure out what the advantages are. The only thing I’ve really found is things like the prepackaged lamp server. I run Ubuntu as a desktop.
My local apache2 is 2.4.7 I’ve been on 14.04 LTS since release.
I don’t make stuff up. 
I chose Ubuntu because when I asked some people experienced with CentOS why it does not support modern software, they said to go with Ubuntu. But Ubuntu was not much better. Until recently with the 14.04 LTS release, it seems. Compiling Apache on Ubuntu took a number of tries until I got it right (and a lot of swearing!). I have not found the time to compile PHP 5.5.x yet. Some people recommend installing packages that contain dependencies PHP needs to be compiled instead of hunting them all down (like aspell and other libraries PHP uses but is not part of the source code). My concern is that anything installed as a package to be built into PHP may be out of date as well. So I thought I would hunt everything down and that is a big job.
I am still pretty much a newbie when it comes to Linux. I know Ubuntu is a Debian derivative. If there is a reason to use Debian over Ubuntu, let me know. Right now I have a VPS I am developing a site on and I think I will stick with CentOS and keep cPanel. If I earn enough to break even on that VPS I will get another one and run Ubuntu or perhaps Debian on it. I don’t want any basic LAMP installs. I want to do something that can handle higher demands. I am thinking something along the lines of Apache Event MPM with PHP-FPM, not sure. I know that PHP is not compatible with Apache 2.2 Event (or Worker) MPM module (Prefork is the only one PHP recommends), but I have read nothing about the same with Apache 2.4.
http://www.php.net/manual/en/install.unix.apache2.php
http://wiki.apache.org/httpd/PHP-FPM
I saw this mentioning that PHP 5.5.x and Apache 2.4 are now in the repos for Ubuntu 14.04 LTS:
http://www.geoffstratton.com/2014/05/ubuntu-14-apache-php/
It looks like Ubuntu is mostly up to date. 
Apache 2.4.9 is current version and they are close with 2.4.7 Installing via package manager is much easier than compiling anything yourself!
So to install Java/Tomcat in centos6 server in VM,… I can via Command CLI in the server itself or via SSH from host machine - connect to vm guest machine?
if yes this is true , … commands to install are different between the two ways - eg install Java/tomcat? or are exactly the same?
CentOS’ core repos are a bit old because EL6 is old. EL7 is coming soon which will again carbonize it’s world at php5.5 or something. In the meantime there are easy ways to fix this – we use the repos de remi (http://rpms.famillecollet.com/). They seem a lot more ghetto than they are, apparently Remi is the guy who builds the upstream packages so you just get the same things early. Another option is IUS Community Repo (https://iuscommunity.org/pages/About.html). That is run by rackspace effectively as they need to deliver php > 5.3.3 to clients and had pretty heavily bet on redhat.
Anything you do in the remote terminal should be the same as doing it in the CentOS terminal. If you use VirtualBox, you can install your guest OS once, clone it, and if you screw things up you can delete the clone and clone your base installation again and start fresh.
I must say I am leery of using third-party repos. Since you have more experience at this than I do, I have a question: are there problems with stability or anything else when using new software with Linux distros?
The reason given for not supporting newer software by CentOS users was that CentOS favors stability over cutting edge software. But don’t the developers of Apache, PHP, and other things have to develop on those Linux distributions? And don’t they test for stability before they release their code? I want to know if this “stability” argument is justified or just an excuse given for not staying current.
Actually I was just curious why people choose Ubuntu as a Server, rather than Debian. I’ve just always thought of Ubuntu as the Desktop and Debian as the server. I’ve been playing around with Ubuntu Server in the last few days trying to figure out the differences and if it’s any easier to use.
It usually has been, I’m kind of surprised it didn’t support anything newer until just this month. I’m just coming back to it as a desktop, I used it for a couple years back around the 10/11 release period. Debian Wheezy has been out for a good year now, I think 6 only supported 5.3… which may be part of the reason why Ubuntu only supported that as well.
I don’t think you get more problems using more frequently updated, well run 3rd party repos if you know your stack are pretty safe. Especially with how long in the tooth EL6 is these days and with all the changes in software stacks of late it made sense to go for the 3rd party options here.
Another angle for us is our machine builds are so automated that if something does die we can rebuild things in a matter of minutes.
Update: no sooner did I write about EL 6 being “very long in the tooth” when they have officially dropped EL7 on us yesterday. RedHat is out now, centos should be coming shortly.