Red Hat Enterprise Linux 5 (RHEL 5) is out and brings in the concept of virtual platform wherein multiple operating systems can run on the same physical box. The release news also says that RHEL 5 is Web 2.0 ready as it also provides the capability to run as webtop meaning web based operating environment. I am glad that the Indian Government is going for open source environment for building e-governance systems (Source: The Hindu - Red Hat releases Linux 5). The Q&A session with Scott Crenshaw, Senior Director of Product Management and Marketing for Red Hat Enterprise Linux, on “RHEL 5: What’s coming” published in InfoWorld has some insights on the features of RHEL 5.
Archive for Operating System
If you are thinking of moving to Vista or not, here is a quick slideshow on the pros and cons of Vista from eWeek online magazine. Based on what is important to you, you can run to or run away from Vista. Another point that I think to run away from Vista is the pricing. My personal opinion on this is with more open source and minimal cost commercial Linux Desktops coming up every now and then spending so much money on OS is something I would think of. However eye-catchy the system maybe, ultimately all I need is whether the system helps me work on whatever I want to efficiently and if there is a system that comes for free or with minimal cost why should I go for the heavy price tagged one.
Kudos to the developers of BeleniX, it is a open source Solaris operating system that can run directly from a CD/DVD without installing anything on the hard disk. Belenix was presented and demonstrated in the 6th Annual Conference of Free and Open Source Software here in Bangalore, India. BeleniX was tweaked and modified to run from a pen drive. As storage capacity is becoming more and more indirectly proportional to the size of the device itself apparently the future seems to be to carry the entire hard disk in your pocket and plug it in wherever you are and feel at home. Here is the local newspaper article “PC software on your key chain!” that talks about BeleniX and its developers.
When I was in my college days learning UNIX, me and my friends used to play around with commands that display back a funny message. The command is wrong and is like a question but UNIX responds back with an error message that looks like an answer to that question and it is funny. I just stumbled upon this list again, though most of these do not work in the current *nix environments.
As JDK versions keep coming one in every year, it is difficult to keep track of what runs in which version and you might want to switch between version to execute applications, to learn the newer features of the current version and so on. It is possible to install different versions of JDK in the same box. But every time you go to your command prompt, whatever java path settings you might have set in your environment variable will what be reflected. And if you want to switch to another version you have to change the value of the PATH environment variable to point to the version you want.
Here is a neat way to have a shortcut to get into the command prompt for every jdk version you have in your system.
- Open Notepad
- Key in the following
- Save the file as say tiger.bat under the folder say c:\
- Now right click on your desktop and select New->Shortcut
- In the program location, enter the following
cmd /k c:\tiger.bat
- Click Next and give the shortcut name, say Tiger (JDK1.5)
- Click Finish
- Now double click on the shortcut and in the command prompt type the following command
Got it? You can create a batch file and a shortcut for every JDK you want just by altering the path of the JDK location in the batch file above. So lets go through whats happening here. DOS provides a way of executing commands in batch which means it can parse through a text file and can execute if that line contains a command it understands. Usually this file is saved with an extension “bat”. So in the above batch file, tiger.bat we use the set command to set the environment variables for that session. The first line @echo off says that the cmd program should suppress displaying the command it is executing. Ofcourse it doesnt stop cmd from displaying any command errors or user messages that can be displayed using the echo command.
OK once we have this file ready, we are creating a shortcut to cmd with an argument of this batch file to be executed when the shell is opened. That’s fine but what is the /k doing there? Well whenever you call cmd passing an argument it interprets and takes appropriate action and then quits. The flag /k tells cmd that it should not quit and wait for more inputs at the prompt. Try removing the /k and see the result for yourself.
A lot of times you might have to get down to the DOS shell in order to check out something. For example you might want to check if a site is up and running or you might want to get the IP address of a site and put into your code. In DOS shell normally you cannot copy selecting text and doing a Ctrl+C. There is a simple way to do a copy paste in the DOS shell.
- First create a short cut for DOS prompt on your desktop. Right click on your desktop, select new -> shortcut, for the program location just type cmd, click away next and finish.
- Right click on the newly created shortcut and select properties.
- Select the options tab and in the Edit options section, check Quick edit mode and Insert mode. Click OK to save and close.
Now you are all set. Double click the shortcut which will open up a DOS prompt. Try executing the command, say for example,
Now just like how you would select a text on any windows application, select the IP address that is displayed using your mouse. Once you have selected, right click your mouse. That’s it, this copies the text you have selected in the clipboard. You can paste this in any of your windows applications. If you want to paste whatever you have copied within the DOS shell, then simply at the prompt right click your mouse and whatever text in the clipboard gets pasted. Try it, you will get addicted to it if you are a person who often visits DOS shell and wants information copy pasted from it.
I have received the following mail so many times including an sms about it on my mobile. This is what it says,
“An Indian discovered that nobody can create a FOLDER anywhere on the computer which can be named as CON. This is something pretty cool…and unbelievable… At Microsoft the whole Team couldn’t answer why this happened!
TRY IT NOW, IT WILL NOT CREATE CON FOLDER.”
Here is the justification why a folder named “CON” cannot be created. Windows has been inherited from MS DOS which again was inherited from an operating system called QDOS (Quick and Dirty Operating System). Till today all the MS operating systems including the servers still have the kernel shell functions of MS DOS. DOS was a text console based OS. CON is a reserved word which meant console or the visual display unit. So anything when redirected to CON went to the display device which is the monitor. Since it is a reserved word DOS restricted that word to be used elsewhere like creating file named CON or creating a directory named CON. Here is a sample test. Go to DOS prompt. Type this command,
c:\> copy con Hello
Keep entering text as many lines as you want and when you are done press (Ctrl key + Z). Give Dir command and you can see that a file named Hello was created. What that command essentially does is create a file whatever that is typed and displayed onto the console. Lets try another example. Try this command
c:\> copy con
Enter some text and press the enter key. What do you see? DOS will echo whatever you have typed. press Ctrl + Z to come out of it.
There is no other reason other than CON being a reserved word and to retain the functionality of DOS shell, that Windows does not allow a folder to be created with the name CON. So you must be wondering if there are any other reserved words and you cannot create a folder with that word. Here is the list. If you create these folders in windows explorer it will create them but internally it is represented differently. To really test it is not possible, go to DOS prompt and try creating a directory (using mkdir command) with the below names.
PRN - refers printer
NIL - refers void (DOS will fool you that it created a directory but it wont be there)
AUX - refers to the auxilary device
COM1 - COM 1 port
COM2 - COM 2 port
COM3 - COM 3 port
COM4 - COM 4 port
LPT1 - LPT 1 port
LPT2 - LPT 2 port
LPT3 - LPT 3 port
And this is only in DOS and Windows systems, it will work pretty cool on a Unix system. Sometimes we get so excited by such mails that we are focused only in forwarding them, rather than trying to find out if the claim is valid.