FTP is the most commonly used for transferring of the files between the servers and computer and there are many FTP clients like filezilla which can be used to transfer file via FTP between various computers no matter which operating system is being used on it.

You might want to go through my previous post on Overview of FTP on Enterprise Linux convering all the basic details which will be used in configuring an FTP in this post.

Ensure that FTP is allowed through the firewall else SELinux is off and iptables are off. Start with installing the FTP package “vsftpd” using YUM. For creating a Yum in Enterprise Linux you may want to go through this post. You need to have root access in to configure an FTP Server.

#yum install vsftpd

(more…)

FTP is a File Transfer Protocol which helps you to download or upload your files to server securely from a remote location.

FTP uses a virtual login to server and is security enabled.

FTP is shipped in Linux with a package named “vsftpd”. You may install the vsftpd package using the yum. you might want to check my earlier post on making a local yum repository or a public yum repository.

The DAEMON i.e (Disk and execution Monitor) for FTP is /usr/sbin. Through Daemon you may start or stop the service.

Some other useful information about FTP is

Type:- system v-managed service (standalone service).

Ports:- ftp(121) and ftpdata(20)

Package:- vsftpd

Daemons:- /usr/sbin/vsftpd .

Document:- /var/ ftp/ pub

Configuration file:-

• /etc/vsftpd/vsftpd.conf      (main configuration file)
• /etc/vsftpd/user_list           (user list not allowed to login through ftp)
• /etc/vsftpd/ftpuser              (Second configuration file with user list)

You would need to deselect the user e.g. root , from both the file listed above in order to login through the FTP.

Once FTP configured you may login to Remote Linux server using FTP client like filezilla.

You may login as “anonymous” user through FTP but it is not recommended. Always maintain a separate FTP user list in order to authenticate through FTP.

JNDI is an API built in Java technology which provides naming and directory functionality to applications written in the java programming language. It is designed using Java object model and used specifically for the java applications. Using JNDI, applications can store and retrieve named Java objects of any type.

It enables applications to access different, multiple, naming and directory services using common API which makes it possible for the different naming and directory services providers to be plugged seamlessly behind this common Api. So Java technology based applications to take advantages of information in a variety of existing naming and directory services such as LDAP, NDS, DNS and NIS as well as enabling applications to coexist with legacy software and systems.

Using JNDI as a tool, new powerful and portable applications can be built that not only take advantage of Java’s object model but are also well-integrated with the environment in which they are deployed.

Oracle applications have a three-tier architecture which comprises of a database tier which manages the oracle database and stores all the data; an Application Tier which hosts various servers, manages communication between the desktop and database tier and contains the application file system; and a client Desktop through which users access Oracle applications.

(more…)

Shell scripts are text files containing commands to be executed.

Shell scripts are useful for:

• Automating commonly used commands
• Performing system administration and troubleshooting
• Creating simple applications
• Manipulation of text or files.

A shell script is simply a text file containing commands. Scripts are useful for automating processes that you perform repeatedly at the command line. For example suppose every morning when you log in, you perform the following operations:

• Check the system dare.
• Look at the calendar for thr current month.
• Check your email.
• Display the list of logged in users.

Instead of entering the commands to perform steps 1-4 individually, you could create a shell script containing those commands. Every morning you could enter just one command to perform all these steps. In addition the key benefit of using Linux is using the powerful, yet simple commands. These commands may be put together in a script to perform complex operations or automate procedures such as adding batches of users.

Linux users involved with system administration and troubleshooting often work with shell scripts. Many of these are created during the installation of the operating system. Consider the script /etc/profile. This file is the system- wide user login script which runs whenever a user logs into the system. System administrators and troubleshooters will consider operations performed in this script when troubleshooting user login problems.

Programmers often create simple versions of programs using scripts during the initial phases of a programming project. This is called application prototyping. Once they and the program’s users are happy with the main functionality of the program, the programmer will then create the full-featured program in a programming language such as C.

The CISC Approach:

CISC stand for “Complex Instruction Set Computing”. CISC is a CPU design techniques and makes the use of complex instruction architecture for performing the processing and execution of the tasks. The primary goal of the CISC architecture was to reduce the execution of the task in as minimum assembly language programming as possible. In order to achieve this goal the main emphasis was on the computer hardware that can understand and execute a series of the operations. It was capable to execute the several low-level operations (like memory store, load from memory) and is also capable of multi- step operations within the single instructions. So for multiplying task the CISC processor would come prepared with a specific instruction in the form of “MULT”. When the MULT was executed, the instruction will load the two values into the two separate registers, multiplies the operands, and then store the product in the appropriate register. So for multiplying two numbers the instruction used was:

MULT 4:5, 7:8

MULT is known as “complex instruction” which operates directly in memory and doesn’t any loading and storing of the functions.

Examples of the CISC instruction set architectures are System/360, PDP-11, VAX, Motorola68k and x86.

The advantages include such as that compiler has to do very little work to translate the high level instruction statement into assembly and as the length of the code is small so very little RAM memory is required to store the instructions. The main emphasis of this architecture was to put on the complex instructions directly in the hardware.

(more…)

Skype is a voip i.e. voice over internet telephony service which also provides you with the features like chat, video-voice chat, screen sharing, and calling telephone numbers at cheap call rates throughout the world almost in all the countries.

The major feature of skype is its online calling service between the PC is absolutely free and moreover has an excellent sound quality. Moreover the call rates are also very cheap.

You can install the skype on Linux as follows.

• Download the skype installation software from here .
• Change your directory to were you have saved the setup files which in our case is at Desktop of the root user.

#cd /root/Desktop

(more…)

What is a View in Oracle SQL Database?

A view is a logical table based on table or another view which is used to present the combinations of data present in the database. A view as itself doesn’t contain any data but it is more like a window through which the data from the tables can be viewed or changed. The table on which view is based is known as the base table and view is stored as a select statement in the data dictionary.

Advantages of Creating a View:-

• It restricts the data access to predefined tables and columns so that a database user can see only information relevant for him.

• It makes the complex queries easy.

• Provides the data independence.

• Can be used to present the different views of the same data.

There are majorly two types of views:-

1.    Simple Views

2.    Complex Views

The major difference b/w the two lies in the DML operations.

(more…)

Shell script is a series of command’s written in a plain text file. It is somewhat similar to the batch-file in MS-DOS but have much more power and functionality than MS-DOS batch file. The major advantage is that you don’t need to write the same set of instructions again, since you can execute it via your script file.  It is majorly used to automate the tasks of day to day life and moreover can be used to automate the system administration part.

Below is an example of a script file by which you can determine whether a file exists or not. This script is used to tell you only whether file exists or not, but not its location as to where it is located. For that you can use FIND OR LOCATE command. We have created a file named existence-of-file.sh you may create a file with some other name. But it is convenient to save the file with ( .sh ) extension so that at later point of time you can recognize that it is a script file. Also in below code whatever is in front of # is a comment.

(more…)

Mozilla thunderbird is the one of the most famous free open source, cross-platform e-mail and news client developed by the Mozilla foundation.  You can easily receive mail from different mail providers on your desktop and can even store these mails on your local desktop alone. Further you can also remain updated with latest new around the globe or locally by using it. Mozilla thunderbird is just like Microsoft outlook express with only difference is that it supports both IMAP and POP3.  And also unlike outlook express it is open source and can be used equally well on various platforms including Linux. You can simply install thunderbird on Linux by downloading its package from the Mozilla’s site.

Here is a link to Mozilla thunderbird package

http://www.mozillamessaging.com/en-US/thunderbird/

After downloading the package just follow the steps to install and configure an email client

• Navigate to the directory were you have downloaded the package (thunderbird-3.1.6.tar.bz2). In our case it is on the Desktop

# cd /root/Desktop

#ls

(more…)