BASIC OF INFORMATION TECHNOLOGY

Information Technology is the key to development s in the modern era of today's computerized world. It merges the computer and communications in order to make the easy availability of latest information to every one. Different business organizations may not work if they don't have the required data and information  for running their business activities. An example of this may be that an airline reservation company that may not be able to prepare the passengers list for its various flights if the required data about passengers is not available or a bank may never perform its banking functions without the data and information regarding its customers and other business perspectives.

As computer is a very important tool for quick and accurate production of our needed information, it is therefore the central topic of information technology, that how a computer performs its computation functions. The other element of IT is called communication, which actually means that how computers r receive the same from them.

In many business organizations, IT plays a significant role mostly in the form of computer based information system like Management Information System (MIS), Decision Support System (DSS), Executive Information System (EIS), Operational Information System (OIS) and so on. The detailed discussion about information system is out of the scope of this however the meanings of information technology may be clarified that is the technology based upon the use of computer based information system having the objective of easy and quick information production, distribution among its end-users, storage, retrieval and use. This information is obtained from the data collected from different data sources in many business organizations.

The benefits of Information Technology are highly adequate, challenging and outstanding. IT now a days is playing its role in almost all aspects of our social, national and international life affairs and in a very true sense, latest information is highly crucial for the betterment of a nation.

1. Components of Computer System:
   A computer is not an ordinary machine but it is a complete functional system that exists due to the integration of two basic components i.e. hardware and software. Hardware is the physical component whereas software is the nonphysical component of the computer system. Here physical component means the one that can be seen and touched directly, where the adverse of this is the nonphysical i.e. the one which can not be seen and touched directly but can be found responsible for running the computer system. An example of this may be the living human body in which there is soul, wisdom, power and other characteristics that exist but can not be touched and seen physically. On the other hand, the different physical organs of the human body can seen and touched but they can't work without soul. In the similar way, computer system will be no more than collection of different equipments without the software. The basic definitions of these two components are given below:
• Hardware is the collection all those parts of computer system, which are actually working during the processing of data to get information.
• Software is a set of instructions (programs), which is responsible for monitoring the different tasks of the computer hardware during the processing of data into information.
  
  Command examples of hardware are processor. RAM, ROM, Hard Disk, Floppy Disk, Keyboard, Printer and so on. Whereas all those programs like operating system, device drivers, commands and computer programming languages etc, which are used to direct the computer hardware about the computational tasks that they perform, are examples of software. The types of hardware and software components will be studied in a great detail in the coming chapters of this book however ti will be better to discuss to main categories of computer hardware and software so that one could be able to understand the way in which the computer system is working.
1. Main Categories of Computer Hardware:
   Computer hardware falls into the following main categories:


• Processor
• Main Memory composed of RAM & ROM
• Secondary Memory composed of mass storage devices such as Hard Disk, Floppy Disk, Magnetic Disk, Compact Disk (CD), USB (Flash or Data Traveler)
• Input and Output devices like Keyboard, Mouse Printer, Scanner, Digital Camera, Microphone, Speaker and so on.
• Sources of interconnections among the above four components e.g. ports, buses, cables and connectors etc.
• Other networking hardware used to connect one computer with another one, such as MODEM, Bridge, Router, Hub, different types of cable media and so on.
  
  In these categories of computer hardware, the above 5 categories are highly necessary for a computer system in a working condition whereas the last category of hardware is required only in case of establishing a computer network. The first 3 categories of hardware are contained within the Central Processing Unit (abbreviated as CPU box) whereas the Input and Output devices are out of the CPU box and are connected to it through their cables. The main memory which is composed of RAM and ROM is directly connected with the computer processor and is thus called online to the processor whereas the mass/secondary storage and Input / Output devices are connected to the processor through main memory especially through RAM and are therefore called peripheral devices or offline to processor. 
  
  
  In the above figure, the bi-directional arrows mean the transfer of data in both directions whereas the unidirectional arrows mean the transfer of data in just single direction. The way in which the computer work may be described in the following steps:
1. Data is sent into RAM (Random Access Memory) from the input devices. 
2. For processing, the data present in RAM is given to the processor from where it is sent back to RAM after necessary processing.
3. Data can also be stored permanently in secondary memory (if required) from where it can be retrieved back into the RAM.
4. The output i.e. information obtained after the processing of data can be displayed through output devices.
2. Main Categories of Computer Software:
   There are two broad categories of computer software, which are described one by one below:
• System Software runs and monitors various hardware devices during their functions. The orientation of system software is towards the computer hardare and makes it available to the computer users for their computation tasks.
• Application Software or  packages are used for working in a particular area of application like Engineering, Graphics, Documentation, Accounting and so on. These software are applicable only in their specific field of application and can't be used everywhere.
3. Data and Information:
   The basic objective of hardware and software component of a working computer system is that they process the data accepted as input and convert it into output called information. If hardware performs actual computational work, software directs computer hardware about the way to perform.
   
   The difference between data and information is that data is just a collection raw facts and figures and it can't be used for decision making whereas information the processed form of data on the basis of which one can make decisions. Data is input to the computer where information is output from the computer system. An example of this may be the data obtained from admission forms of students. The college administration can't decide about which students should be admitted and which not on the basis of this data. However if this data is properly processed according to a set of procedure (software), the clerical staff and machinery equipment (hardware), it is converted into students merit list on the basis of which one can easily decide about student admission. This transformation of data into information is the basic goal of a computer based information system comprising necessary hardware and software components.
2. Input & Output Devices:
   As a computer system processes the data i.e. raw facts and figures into their information products, specific devices are used for input of data and display or output of information. These enable the computer system to interact with its users. These devices are also called input/output peripherals. Examples of input devices are keyboard, mouse, jay-stick, scanner, digital camera and microphone etc whereas common examples of output devices are monitor, printer, plotter and speaker etc. 
3. Operating System and Computer Programs:
   The data that is input to computer system may be processed and transformed into information products. These computational activities of data input, processing and information output are performed with the help of various hardware devices under the supervision of a set of computer programs i.e. operating system and other application or system software. An operating system is the most significant kind of system software that contains certain distinctive characteristics like:
• Managing the software and hardware resources of the computer system.
• Controlling the functionalities of all hardware and software resources in addition to their management.
• Providing user-friendly interfaces that enable users to operate the compute system.A system software that is equipped with all of such feathers will be an operating system however if any of these features is missing within a system software then it will be an ordinary system software or an application software have their important roles in the computational activities of transforming data into information.
4. Data Storage and Memory:
   Storage of data is important computational process that is carried out in order to use the data for future needs. Two types of data memories are associated with the data storage i.e. primary memory (RAM & ROM) and secondary memory (Hard Disk, Floppy Disk, and Magnetic Tape etc). The former i.e. primary memory also called internal memory is online to the processor and is composed of RAM and ROM. RAM is the only part of the primary memory that can be used for storing the users data temporarily whereas ROM can't be used for storage of user data as it is read only and we are unable to write or store our data into the ROM. On the other hand RAM (Random Access Memory) also called Read/Write Memory may be used to store the data temporarily as long as the computer is on. As soon as the computer system is shutdown, the data present into the RAM is washed away. RAM is the only way of users data to the processor because processor is directly connected to RAM and picks data from RAM to process it.
   The other type of computer memory is called secondary memory or external memory or auxiliary memory or mass memory. It stores the data permanently with the help of magnetic mechanisms however unlike primary memory, it is connected to the processor through RAM i.e. the data from the secondary memory is carried to RAM before it is processed. That is why secondary storage is also an offline or peripheral device of the computer system.
1. Basic Unit of Data Storage:
   The basic and smallest unit of computer memory is called bit that stands for binary  digits. As we know that computer internally represents its data in the form of binary zeros and ones, these bits are the primary sources of such representations. A bit may have two possible states i.e. 0 or 1. 0 is used for circuit off whereas 1 is used for circuit on. Thus a single bit may have two possible representation of data 0 and 1. Some other larger units of computer memory are given below:
• Nibble:
  One nibble is the combination of 4 bits. It can have 16 possible representations of data as 2⁴=16. An example is the Hexadecimal number system, which is composed of numbers from 0 i.e. 0000 to F i.e. 1111.
• Byte:
  A byte may be defined as "the memory required to store a single alphanumeric character of data." Here alphanumeric character may be any digit from 0,1,2,3,.......0 or an alphabet from a to z or A to Z or any other special symbol like , : / ? + - * etc. A byte is a combination of 8 bits or 2  nibbles. As a single bit can have 2¹=2 possible representation i.e. 0 and 1, therefore a Byte i.e. a combination of 8 bits can 2⁸ =256 possible representations of data in the form of 0s and 1s.
  Some commercial units of data storage that are composed of bytes are described in the table below:
  

  Name of Unit	Abbreviation	Numbers of Bytes
  Kilo Byte	KB	(2)10
  Mega Byte	MB	(2)20
  Gega Byte	GB	(2)40
  Tera Byte	TB	(2)80

  
  Example: Calculate the total number of Bytes and Kilo Bytes in 256 MB of RAM.
  
  Solution:
  This problem can be solved as:
  
  Number of Bytes in 1 MB = 2²⁰ Bytes
  So total number of Bytes in 256 MB of RAM 256 x 2²⁰ Bytes = 268435456 Bytes
  Similarly, the number of Kilo Bytes within 1 MB =2²⁰ KB or 1024 KB
  So the total number of Kilo Bytes within 256 MB RAM = 256 x 1024 = 262144 KB
• Word:
  A word is a combination of 2 Bytes. Some machine instructions need computer words comprising 16 bits. However the larger units that are composed of words are described in the table below:
  

  Name of Unit	Abbreviation	Number of words	Number of Bytes
  Double Word	DW	2	4
  Quad Word	QW	4	8
  Double Quad Word	DQ	8	16

  Example: Calculate the total number of Words, Double Words and Quad Words in a hard disk having a storage capacity of 40GB.
  Solution:
                 In order to solve this problem, we will have to find:
                Total number of Bytes in 1 GB =  2⁴⁰ Bytes
                Total number of Bytes in 40 GB = 40 x 2⁴⁰ Bytes
                Number of Words contained in 2 Bytes = 1 W
                Number of Words contained in 40 GB = 40 / 2 x 2⁴⁰ Words= 20 x 2⁴⁰ DW
  Similarly
                  Number of Double Words contained in 4 Bytes = 1 DW
                  Number of Double Words contained in 40 GB=4x2⁴⁰DW=10x2⁴⁰DW
  and in this way
                  Number of Quad words contained in 8 Bytes=1QW
                  Total number of QW in 40 GB=40/8x2⁴⁰QW=5x2⁴⁰QW
  Example: Calculate the total number of characters possibly represented by a single Byte.
  Solution:
  It is to be noted that one Byte can represent just a single alphanumeric character at a single time. As a character is a combination of 0s and 1s in binary form, this problem can be solved as:
                            Total possible states of a single bite =2 i.e. 0 and 1
  This means that a single bit may represent 2¹ possible states. Since a Byte is a combination of 8 bits in usual conditions, the total number of possible representation of 0s and 1s by a single Byte are 2¹ representations. Thus 2¹ or 256 possible representations characters may be represented by a single Byte, which in other words means that 256 characters may possibly be represented by a single Byte.
5. System Development:
   After discussing the fundamental concepts about the computer system and its working. Lety us study computer based information system briefly. A system in a wide sense may be define as "an integration of components or parts linked together according to some specific scheme to achieve certain common objective". According to this definition, some systems are natural, some are man-made and some are computer based. Here emphasis is the computer based information system i.e. the system that uses computers and communication equipments for the delivery of information to the different levels of end-users in a business organisation. These computer based information system play and vital role in information technology and their potential uses are so many that will be out of the scope of this discussion. However a brief overview of computer based information system development is useful to know how the software development process for an information system is performed.
   
   Developing an information system is not an easy task rather it may be troublesome in some respects as it involves several distinct phases each of which must be completed before a subsequent task can begin. For this purpose, the system development life cycle is adopted so that a successful information system may be achieved. A system development life cycle is a repetitive process in which a system may be created, upgraded, matured, in its operations and may die  with the introduction of new hardware and software technologies, environmental changes (like government policies or customer demands) and so the introduction of a new information system before. The system development life cycle is composed of the following phases:


1. Problem Definition: 
   It is also called problem identification and is somewhat similar to the famous saying that necessity is the mother of invention and it tend to find out the problem and its reasons that motivate the huge projection of information system development. This is the first and the most crucial step in system development. The whole system depends upon this step because the actual problem due to which the system development is initiated is identified in this step and all of the future work will be correct if the definition of the problem is correct or otherwise all of the future efforts, money, time and other assets used for development will be wasted. The reason behind the dependence of system development will be wasted. The reason behind the dependence of system development on correct problem definition is that if a problem is correctly identified, it means that it has been solved almost about 50% and the rest of the solution will depend upon the practical work in correct direction whereas if a problem is identified with inaccuracy in its definition then it means that the direction of solution is wrong from its very beginning and the process of system development will miss its target if continued this way.
   The reasons behind problem definition and new system development may be:
   
   *     Current system is difficult to use.
   
   *     Current system doesn't work according to the expectation of its users or it is producing inaccurate result.
   *     The current system needs to be improved for making it more efficient.
   
   Once any of such things happens and the problem is realised, the system analyst is requested for change in the current system improve its outcome. The system analyst begins a preliminary investigation to find out the problem and its sources accurately. The definition of the problem results into the submission of report that is put before the management of the business organisation and about problem definition may contain.
   
   *     The correct definition of the problem.
   *     The rough cost estimation for solution to the problem.
   *     The amount of time taken by this development project or project duration.
   *     Staff required e.g. programmers, project managers, operators and so on.
   *     The hardware and software technologies needed.
   
   On the basis of this report, management of the organisation may decide whether to approve the development project or not.
2. Analysis:
   When the authorities or management of the business organisation take a decision to proceed with the solution of the problem, the next step is to thoroughly investigate the entire current information system. The system analyst has to work very close to people directly facing the problem and finds out how it can be solved. In this phase, the present system is studied in depth to collect all the available information about the current system. The most commonly used techniques are:
• Review of Existing Records:
  This means that all the available written or computer-stored material about current system may be collected and studied.
• Interviews:
  An interview is the face-to-face communication between two persons. It can be used to arrange meetings with the users of current system. It may be very useful as it produces upto-date information that can not be documented officially. The system analyst may also be able to judge the truth of answers from expressions of the interviewee.
• Questionnaire:
  In this technique, a set of proposed questions with a proper space among them is arranged for the collection of information about the current system. It is usually used in case when the business organisation is spreaded over a wide geographical area and interviews take a lot of time and cost.
• Observation:
  As its name indicates, it is that technique with the help of which it is observed that what people at a place e.g. in the different sections of business organisation are doing and what actions are taking place over there. This means that we have to observe the people at work. This is very useful in checking the truth of information collected through interviews and questionnaires.
  After all the information is collected about the system, the system analyst has to analyse the information and purpose a set of solutions to the problem. A typical solution may include:
  *     What should be the output given by the system?
  *     What should be input into the system?
  *     What should be the hardware and software of the system?
  *     What tools are needed for the system?
  Throughout analysis the focus remains on "What the system must do?" and "How the system is to be developed?" After all the solutions are defined, these are given to organisation for selecting the best possible solution. These solutions are identified on the basis of constraints, budgets, resources and schedule of the organisation.
3. Design:
   In this phase the project team develops software for information system. The best solution selected from the set of alternative solution or candidates found in analysis phase and is programmed. Here emphasis is the practical or physical design of solution to the problem. This design include input design, process design, file design and output design i.e. the different component of the information system are designed in this phase. There are two types of system design.
• Logical Design:
  In which different algorithms and system flowcharts are designed. One has a clear understanding about how proposed information system will perform its functions and how it will be free of the problems existing in the current system. This design is very important because it provides a road map for the proposed information system to work and it also has its impacts on the later coming physical design so great care must be taken in logical design.
• Physical Design:
  Physical design or coding in which software for proposed information system and its components is prepared in the light of algorithms and flowcharts obtained from logical design process. The outcome of physical is the information system software in its crude form. The actual work of information system development takes place in this phase to create a newly proposed system software solution in its practical form.
4. Testing & Debugging:
   The newly created information system may contain serious bugs in it that need t be properly refined so that it may be able to smoothly handle the business activities of organisation. For this purpose, a detailed software testing criteria is adopted to check its quality, performance, speed and working in real world situations. The software is tested with dummy data and if it works correctly, it is recommended for other tests. If all the test are satisfactorily cleared then it is finally tested for acceptance. Successful clarification of this test will bring it into its practical implementation. Any weakness or bugs found in testing process are attempted to be removed and the system is properly refined to make it capable of working with original data of business organsiation.
5. Implementation:
   In this phase of system development life cycle the system analyst and his/her project team puts the developed system into practice after thorough testing and debugging. Implementation may consist of several steps like purchase of necessary hardware and other materials required for system, installation of new hardware and software, conversion of data files to use them in the current system and so on.
   
   After installation conversion takes place, which is the process of moving from the old system to newly developed system. These conversion phenomena may be accomplished according to the following four methods:
1. Direct Conversion:
   Direct Conversion or Abrupt Cutover is that method of conversion in which users immediately stop using the old system and begin using the new system. This method is fast but is highly risky and in case when some problem occurs in working of the new system, entire business of organisation will badly suffer and there will be no way to go back to use the old system for recovery.
2. Parallel Conversion:
   Parallel Conversion is that method in which both new and old system are used for some time. Outputs of both of these systems are compared and in case if they match together, then we switch from the old system to the newly created information system. This method is safe but it is highly time consuming and expensive as the organisation has to run two systems at same time.
3. Phased Changeover:
   Phased Changeover is the method of conversion into new system in a component-by-component fashion so that first component of the newly developed system is installed first and if it works accurately then the other components will be installed in sequence.
4. Pilot Conversion:
   This method is adopted in case when organisation is spread over multiple locations. The newly developed system is tested in single pilot phase and if it works correctly then the entire organisation switches from old system to newly developed information system in all of its locations.
   
   It must be notified that proper training and personnel support play important role during the conversion or changover phenomena. These people deliver lectures, hands on training and computer training to the end-users of the newly developed system.
6. Maintenance: 
   This phase is also called post-implementation as after the implementation of the new system, the Information System Department (i.e. the developers of new system continue to provide their support to the new system in order to ensure that it works properly. It involves:
   *     Corrections of errors that occur in the newly implemented system.
   *     Changes due to changes in the organisation.
   *     Changes or upgrades or improvements in the system.
   Post-implementation or maintenance guarantees the long life of the system in the business organisation and it ensures that the newly implemented system may work fine for longer times. A detailed documentation is also accomplished starting from problem definition to the post-implementation phases of system development life cycle so that it may provide detailed information about the system if at any time problems arise in the newly implemented system. This may be specifically helpful for other system analysts or IT professional (who will join the Information Department later on) to understand the newly implemented system and maybe capable of handling any problem in it.
   The system development life cycle is diagrammatically represented in figure below:
   
   
   From this diagrammatic representation of system development life cycle, it is clear that as soon as the newly implemented information system becomes old after a fixed period of its life, problems will arise in its operations. Consequently development of another information system becomes crucial. This process will again take a start from Problem Definition phase of the system development life cycle and will end at Post-Implementation or Maintenance phase. That is why system development is continuously repetitive or cyclic process that takes place over and over with the introduction of new hardware and software of computer system certain other factors.

LINUX COMMANDS

There are some commands which are used in LINUX operating system which are as follow:

1. Clear Command:
   The external clear command clears your terminal screen if possible.
   $ clear and press (Enter)
   The terminal screen is cleared and the shell prompt $ appears at the top of the screen.
2. Pwd Command:
   The internal cd command changes your current working directory. cd lets you do the following:
   -          change working directory.
   -          change to last previous working directory.
   -          use a sting substitute in the current path to change to a similar directory path.
   The general format of the command is:
   $ chdir/cd-
   $ cd [directory]
   $ cd.. The present working directory is changed to previous working directory.
3. Mkdir Command:
   The external mkdir command makes a new directory. You can pass multiple arguments to mkdir. Each argument is used by mkdir as the name of a new directory to create.
   The general format of mkdir command is:
   $ mkdir [-m mode] [-p] directory_lisht
   Options:
   -m mode:
                     Mode to use for new directories. This allow you to specify what mode all of new directories will have when they are created
   -p:
                     Parent directory creator. If you specify a pathname to create a new directory and the parent directories do not exist, mkdir will create them as needed.
   Note:
                     You have must have write permission fr the directory when you are creating new sub-directories. If no write permission is available, you will not be able to create a new directories.
   Example:
1. To create a sub-directory called misc which has another sub-directory named misc1.
   $ mkdir misc misc/misc1
4. Rmdir Command:
   The external rmdir command remove a directory. The directory must be empty.
   rmdir is a safe way to perform directory removal than using rm -r command. It checks the directory for existence of files and sub-directories. If any exists, rmdir complaints and exits without removing the directory.
   The general format of rmdir is:
   $ rmdir [-ps] directory_list
   Options: 
   -p
                Removes empty directories specified in the directory path. Name of each directory is displayed on standard output as it is removed. Directories that are not removed are displayed on standard error.
   -s:
                 Suppress any messages produced. Both standard output and standard error are suppressed.
   Examples:
   
   1. $ rmdir misc/misc1 misc
      to check whether the directories misc and misc/misc1 are removed use the following command to list the directory.
      $ Is -l
5. Cat Command:
   The external command reads each file in the argument list and displays the data to the standard output. It only writes to the standard output. By using shell re-standard input. It only writes to the standard output. By using shell redirection capabilities cat can be used to combine multiple files into one large file that is why it is called concatenate. Some of the uses of cat command are as under:
   -              Display contents of ASCII files.
   -              Make a copy of a file.
   -              Combine multiple file into one file.
   -              Copy input from your keyboard to a file.
   -              Send output to a pipe used for multiple file input.
   -              Combine input from screen and a file into one output stream.
   General format of the cat command is
                  cat [-] [-su] [-v] file_list.
   Option:
   -:                      Read from standard input, treated as one input file.
   -s:                    Error  messages for non-existent files are suppressed.
   -v:                   Prints non-printing characters is visible form. Control characters. e.g., Control-X is printed as ^X.
   -e:                   Print as $ sign to represent new-line character.
   -t:                   Print a ^I (Control-I) in place of tabs.
   file_list:         One or more files in sequential order and write to standard output. If no argument is specified cat reads from standard input.
   
   Example:
   1. $ cat my-file.                                                          To display a file.
   2. $ cat my-list your-list his-list                                 To display multiple files.
   3. $ cat original-file > his-list                                     To copy a file.
   4. $ cat file1 file2 file3 > file 123                               Combining multiple files.
   5. $ cat > new-file                                                       Creating a file from keyboard.
      { here you type whatever you like and at the end press Ctrl-D}
6.  Is Command:
   Is command is used to display files and directories names. The format of Is command is:
              $ Is [option] [file-names or wild cards]
   Some of the essential option are:
   
   • a:
     Lists all files. Including hidden files starting from "."
   • -d:
     Displays data about directories.
   • -l:
     Long list files and directories.
   • -t:         
     List file in order of last modification time.
   • -R:       
     Recursively lists file in all sub-directories.
   • -r:        
     Displays files in reverse alphabetical order of filenames.
   • -U:      
     Sort entries by the last access time.
   • -x:       
     Sort files by file extension in alphabetical order.
7. My Command:
   The external my command moves a file from an existing location to a new location. It is also used as the rename command to change the name of a file. It has three formats:
   -           Rename a file with a new directory name.
   -           Move one or more files to reside under a different directory.
   -           Rename a directory with a new directory name.
   General format of the my command is:
                $ my [-if] file-name new_file-name.
                $ my [-if] file-name directory.
                $ my [-if] old_directory new_directory
   Option:-f:         Force the move to occur. Response "Yes" is assumed and move is performed.
   -i:         Commands runs in interactive mode. If destination file already exist, my prompts you with the file-name followed by a question mark (?). If you respond with "Y" or "Yes", move is performed. Any other response will cause my to skip to next move.
   
   Example:
   1. Display the list of files in the current directory
      $ Is -x
      caller file1 file2 db letters
   Now use my command to rename the file file2 as stuff
                $ my file2 stuff
                Now display the list of files
                $ Is -x
                caller file file1 db letters stuff
8. CP Command:
   The external CP command copies a file. It reads the contents of a file and creates a new file or overwrites an existing file. There are two basic formats of CP that allow you to:
   -          copy one file to another file.
   -          copy multiple files to a directory.
   -          copy input from your keyboard to a file.
   -          copy a file to your terminal.
   General format of the cp command is:
        $ cp [-ip] source_file dest_file
   $ cp [-ipr] source_file_list dest
         directory
               $ cp [-ip] source_directory
                      dest_directory
   First format copies one ordinary file to a new file. Second format will copy one or more files to a specific directory. Third format allow you to copy an entire directory structure to a new directory.
   Option:
   
   • i:
     Interactive confirmation is required. You are prompted if an existing file is overwritten. If "Y" or "Yes" is given in response, copy is performed otherwise not.
   • -p:
     Preserve the characteristics of the source file. Copy the contents modification times and permission modes of the source file to the destination file.
   • -r:
     Recursively copy and source directories. If a directory is given as the source file, then all of its files and sub-directories are copied. The destination must be a directory.
   Example:
   
   1. $ cp letter letter.bak                                       make a backup copy of file letter
   2. $ cp letter ../temp                                           copy letter to temp working directory
   3. $ cp /dev/tty note                                           copy input from keyboard to file note
   4. $ cp file1                                                        copy file1 to file stuff
   5. $ cp calendar letters                                       copy file calendar directory
9. RM Command:
   The external RM command removes (delete) files or directories.
   The general format of the RM command is
                       $ rm [fi] file_list
                       $ rm [-fir] directory_list [file_list]
   Option:
   
   • -f:
     Forces the removal of all files listed. Does not check whether file is write-protected or not. Does not prompt for confirmation. If directory is write-protected, files are never removed.
   • -i:
     Interactive file removal. Response is awaited.
   • -r:
     Recursively removes files and directories. All files are removed from each directory. Each directory is then remove. If a file is write-protected, then rm prompts you for confirmation to remove the file.
   Example:
   
   1. # rm stuff                            to remove a file named stuff
   2. $ rm-ri letters
      letters calendar ?y
      letter ?
      press Return not to delete letter directory
10. More/Page Command:
    The external more command allows you to view a file on your terminal.. It lets you view one screen of text at a time. The page command performs the same function as more but with a different screen control. The screen is cleared before each full screen of text is displayed.
    The general format of the move command is:
                                       $ more [-option] [+linenum] [file_list]
    OR                             $ page [-option] [+linenum] [file_list]
    Option:
    
    • -f:
      Do not long lines. Court logical lines instead of screen lines. Normally more truncates lines longer than the screen width.
    • -s:
      Squeeze out adjacent blank lines. Two or more blank lines are grouped together and are reduced to one blank line. This increase amount of text displayed on the screen.
    • -w:
      Prompts and waits for any key to be pressed before exiting. By default more / page will exit without waiting when end-of-file reaches.
    • -rows:
      Specifies the No. of rows (lines) to display on your terminal screen.
    • +linenum:
      Begin display at line number linenum of the input.
    • file_list:
      The list of files to be read by more.
    Example:
    
    1. Type more/etc/passwd /etc/group /u/ts/my/login/file1 and press Return. First screen of /etc/passwd file appear.
    2. Press Speacebar, next screen of data is displayed. (If the data in the file has been finished, next file is started)
    3. Type 2:n to skip to /etc/group file. The output will like
       .... skipping
       .... skipping to file /ul/ts/mylongin/file1
                       ---more---(Next file:/ul/ts/mylogin/file1)
    4. To return to second file, type :p to skip backward to /etc/group file.
       ... skipping
       ... skipping of file /etc/group
       ---more---(Nextfile:/etc/group)
    5. Press Spacebar to move forward on screen.
    6. Press Spacebar to move until (Next file: /ul/ts/mylogin/file1) appears
       At the end, type 'q' to exit from more.
11. Grep Command:
    Search files for lines matching a specified pattern and display the lines:
    Syntax                 Grep [option] [pattern] files
    Option:
    
    • -c:
      Instead of displaying matching lines simply output a count of total number matching the expression.
    • -i:
      Ignore case in both the pattern and file.
    • -L:
      Instead of displaying each line simply display the names of each file that contains no matches for the pattern.
    • -n:
      Prefixes each out put line its line number in the file.
    • -w:
      Display only those lines with matches for the patterns that complete word.
    • -x:
      Display only those lines with matches for the patterns that complete line.
     
12. Zip Command:
    Create a Zip archive from one or more files and directories.
    Syntax            zip zipfilename file1 file2 file3
    Option:
    
    • -f:
      Recursively work with directories adding all files in the sub-directories to the archive.
    • -m:
      Move files into the archive deleting them form original location.
    • -e:
      Encrpt the archive after prompting for a password this password will be use in extracting.
     
13. Unzip Command:
    Manipulate and extract ZIP archive
    Syntax           unzip [option] ziped filename
    Option:
    
    • -f:
      Extract only those files that are newer than already-existing version of the file.
    • -I:
      Displays the contents of the archive without extraction.
14. Chmod Command:
    Change the access permission of one or more files or directory
    Syntax                chmod [option] mode files
    Option:
    
    • -r:
      Recursive Recursively changes the permissions of all files in all sub-directories.
    • -v:
      Verbose Displays the results of all permission changes.
    • -f:
      Silent Suppress display of error messages when files permissions cannot be changed
      Mode it is in the form [ugoa][+-=] [rwx]
      u            =              user who owned the file
      g            =              all members of the group that owns the file
      o            =              anyone who is not the owner or in the owner group
      a            =              all user
      +            =             specified modes should be add to already specified permission
      -             =             specified modes should be remove from already specified permission
      =            =             specified modes will replace existing permission
      r             =             read permission
      w           =             write permission
      x            =             execute permission
      Example
      $ Chmod u+x a.bat                      will give execute permission to user on a.bat file
      $ Chmod u-x a.bat                       will remove execute permission to user
      $ Chmod a+x a.bat                       will give execute permission to all user
      $ Chmod a=rx a.bat                      will give read and execute permission to all user and
                                                           remove existing permission
     
15. At Command:
    Schedules commands to be executed at a specific time. User is prompted for the commands.
    Syntax          at [option] time
    
    • -f filename:
      Read commands from the specified file rather than prompting for the commands.
      example                    $at 2.30
                        rm*.Temp                ctrl-d
      specifying times
              now                                  =              specifies the current time
              today                                =              specifies the today
              tomorrow                         =              specifies the next day
                   +                                 =               specifies offsets in minutes hours days of weeks
               now + 2 hours                =               3 days from today
      Job Control
      Using Job Control, it is possible to use a single shell to execute and control multiple programs running simultaneously.
      Normally, when you execute a command, it runs in the foreground. That is, the shell executes the command and prompt and the prompt doesn't return until the command is finished.
      I.t. executing a command
                     $ find / -name'*.tmp' -print > findfile
      This command searches the entire structure of Linux system for files with the .tmp extension and store the result in the findfile file. While executing this command you won't be able to run other commands while find is running.
      To place a job in the in background is to add an ampersand(&) to the end of the command when you run it.
                    $ find / -name'*.tmp' -print&
      Once you press enter to execute this command, you are immediately presented with a new command prompt; at the same time and you will be able to execute the next command same time
      Thus you can execute multiple task an the same time
16. Job Command:
    This command will list all jobs running
    Syntax               $ jobs
    
    1. Running                                        $ find / -name '*.tmp' -print > findfile &
    2. Running                                        $ Is -IR / '*bmp' >dirlist &
17. Fg Command:
    This command bring the background job to foreground
    Syntax               fg Jobs no
    Example:
                 $ fg 1
    This will bring $ find / -name '*tmp' -print >findfile from background to foreground ie on screen.
18. Bg Command:
    This command start the stopped job in the background
    Syntax              bg Jobs no
    The foreground job first stopped by pressing Ctrl+Z and command prompt will be available. Where you can run the bg command to run the stopped command in the background.
    Example:
    Suppose you enter another command.
             $ IS -IR / '*.bmp' >dirlist
    This will Execute in the foreground then press Ctrl+Z. This will temporary stopped the Is job.
    And give command prompt to see the all current job.
              $ jobs
    
    1. Running                    find / -name '*.tmp' -print>findfile &
    2. Stopped                     $ Is -IR / '*.bmp' >dirlist &
    Now to start the stopped job ie [2] enter the command and prompt.
           $ bg 2
    To see the result
           $ jobs
    
    1. Running                    $ find / -name '*.tmp' -print >findfile &
    2. Running                    $ Is -IR / '*.bmp' >dirlist &
19. Cal Command:
    The external call command generates a simple calender and write it to the standard output. The default output for cal is current month. Using specific argument, a calendar for specific year or year and month can be created. Valid years are 1 to 9999. Valid months are 1 to 12.
    The general format of the cal command is
    Syntax              $ cal [[month]year]
    year:               Produces calendar for given year
    month:            Produces calendar for specified month of given year
    Example:
    To create a calendar for September 2010, the command is given as:
               $ cal 9 2010
20. Echo Command:
    Displays a line of text to your terminal. Some of the feature and use of echo are
    
    • Display string of text
    • Display variables
    • Display menu screen
    Syntax              echo "string"
    Example:
                $echo "my home directory is $home"
    Result will be display a line of text
                 May home directory is alihomedir
    Sending or eceiving messages from or to another uiser.
21. Write Command:
    The external write command sends message you type on your terminal to another user's terminal. Write reads the standard input and writes to the specified user's terminal tty. The write commands used to communicate with the fellow users on an interactive basis. It is useful to send a brief message to someone immediately or to carry on conversations using terminals. The general format of the write command is:
                          $ write user_name [tty]
    Option:
    
    • \user_name:
      The name of a user who is currently logged in to the system. Use the who command to list who is on the system.
    • tty:
      Specify which terminal tty to connect to if the same user is logged on more than once
    Example:
    
    1. Create a file and type some message in it, then use the following command:
       $ write alpha < tempmesg
       Where alpha is the name of the user to whom the message is to send while tempmesg is file containing the text of the message.
    2. Type the following command:
       $ echo "How are you? I want to meet you in the library at 09:00" ! write alpha. The echo will send the message to write via a pipe. The message will appear on the screen of username alpha all at one time as shown below:
       message from mylogin tty11 [date & time]
       How are you? I want to meet you in the library at 09:00
22. Wall Command:
    The external wall command performs a write to all users currently logged on to the system.
    The general format of the wall command is
            $ wall
    The wall message precedes its message text with the following line:
            Broadcast message from use_name
    It is usually used by super user to warn all users of immediate problems. The most command warning is that the system is being shutdown within 60 seconds.
    The super user can write to any user's terminal regardless of the permissions set by that user using mesg command. The wall command is commonly used by the super user. It can also be used by any user but may users do not need to send message to every one on the system.
    Common formats are:
                  $ wall < mesgfile
    OR        $ cat mesgfile ! wall
    Example:
    
    1.    $ wall
       This is a broadcast message of the Linux Beginners Broadcasting Foundation. Please disregard this message and get back to your work immediately. Ctrl-D.
    The message will also be sent to your tty since you are also logged on to the system. This provides a verification that the message was sent as expected.
23. Man Command:
    The external man command display help about any command to your terminal screen.
    The general syntax format of the man command is
    $ man command
    Example:
             $ man cp
    Will display help page of cp command.
24. Head Command:
    The External  head command will display the first 23 lines of the file on the screen.
    The general format of the head command is
               $ head file_name
    Example:
               $ head abc
    Will display first 23 lines of abc file.
25. Tail Command:
    The external tail command will display the last 23 lines of a file on screen.
    The general format of the tail command is
                 $ tail file_list
    Example:
                 $ tail abc
    will display last 23 lines of abc file.
26. Mail Command:
    The external mail command is an electronic post office. You can send, receive and store messages using mail command. There is a long list of options associated with mail command which can be used according to the requirement. The general format of mail command is
                 $ mail options
    To read mail, use the following command
                 $ mail
    All the messages stored in the mailbox can be displayed.
    To send mail to another user of the system, the following command is used:
               $ mail user_name
    Example:
    
    1. To send mail to a user named alpha
       $ mail alpha and press Return. The following screen appears
       Subject --------------- (type the subject of the message) (type the message) press Ctrl-d to end the message
    2. To read mail, type
       $ mail
       The display will show          mail version................ 01/29/99 type? for help
       Type ? to display the commands to view, edit, delete or store the messages to file. aq
27. Shutdown Command:
    the external Shutdown command will shutdown the system. The root user are allowed to use this command on server, specifying time, will broadcast the message to all connected users. This command be used according to the requirement. The general format of shutdown command is
    Syntax             $ shutdown option time [message]
    Option:
    
    • -h:
      Will halt after shutdown.
    • -r:
      System will reboot after the shutdown or restart the system.
    • Time:
      Time specified in minutes
     Example:
    $ shutdown -h 3 "please save your work, the system is shutdown in 3 minutes.
    
    

HISTORY OF LINUX

HISTORY 

In August 1991, a student form university of Helsinki in Finland began a post to the comp.os.minix, news group with word "Hello every body out there using minix, I am doing a free Operating System (Just a hobby, won't be big and professional like GNU) for 386 (486) at colons. Name Linus Torvalds."

 The hobby he spoke of eventually become what we know today LINUX.

At that time UNIX and other operating systems were costly then PC hardware. While versions of UNIX have long been available for PC's. They never had the grace of power of operating available for mini computers, mainframes and today servers. This lack of accessing ultimately give birth to LINUX as a means to make a UNIX like operating system available on wide spread basis.

Today's Linus was developed with the assistance of programer's word wide; Linus Torvalds still retains control of evolving core of Linus operating system the Kernel ..0000000

In March 1992, version 1.0 of the Kernal was first official release of Linux.

MAIN FEATURE & ADVANTAGES OF LINUX

1. Multitasking Capability:
   Full multitasking and 32-bit support. Linux, is a real multitasking system allowing multiple users to run many programs on the same system at once.
2. Multiuser Capability: Multiuser operating system several users to use the same computer to carry out their computing job. Can run programs, access files and print documents at the same time.
3. System Portability:
   Linux has this outstanding feature that it is not written for specific hardware platforms. It can be ported to another system (installation) without the need to make any major changes.
4. System Security:
   Several levels of security exits in Linux.
• First level is system security is A login is simply the name that you supply to Linux to identify yourself to the operating system. Linux keeps track of which names are permitted to log in or access the system and only allows valid users to have access.
1. Another level of security is when it comes to accessing files. Three permission "Read, Write & Execute" can be assigned by the owner of the file to each of his files. All of these permissions can be individually either granted or denied to all the users of the system.
2. Third level of security allows users to encrypt data files on the disk so that even if someone manage to access then he can't make much sense of it.
5. Linux Application:
• Text & Word Processing Application:
  
  In addition to commercial word processing software's such as Word Perfect, Star Office, Applixware, Linux offers powerful tools for editing text files and processing text in an automated fashion.
• Programing Languages:
  There is a wide variety of programming and scripting languages & tools available for Linux.
• Internal Tools:
  In addition to supporting Well-Known software such as Netscape Communicator and Mosiac, Linux provide wide verity of internet software and full range of software needed to create internet services such as Web Server, Mail Server plus complete network support to connect to the internet via Local Network or Modem. 
• Databases:
  Linux provide robust platform for running client server database application such as free database SQL and postgre available for Linux also commercial database such as Oracle, Sybase and Informix.
6.   DOS & Windows Compatibility:
   Linux can run DOS software with a high degree of stability and compatibility and offers several approaches to run Windows software, Wabi, Win3e, VM ware.
7. Linux is Free Software:
   Linux kernel and most of the applications written for Linux are available for free on the Internet, often with no restriction on the copying and redistribution of the software.
8. Virtual Memory & Shared Libraries:
   Linux can use a portion of your hard drive as virtual memory, expanding your total amount of available RAM. Linux also implements shared libraries, allowing programs that use standard subroutines to find the code for these subroutines in the libraries at runtime. This saves a large amount of space on your system.
9. Linux Support (almost) all of the Features of Commercial Versions of UNIX:
   In fact, some of the features found in Linux may not be available on other proprietary UNIX system.
10. GNU Software support (Free Software's):
    Linux supports a wide range of free software written by the GNU project, including utilities such as the GNU and C++ compiler, gawk, groff and so on. Many of the essential system utilities use by Linux are GNU software.
11. Built-in Support for Networking, Multitasking, & other features
12. X Windows System: 
    The X Windows convert text base Linux to graphics Operating System A complete version of the X Windows System, known as XFree86, is available for Linux. The X Windows System is a very powerful graphics interface, supporting many applications.

HARDWARE REQUIREMENT

You can run entire system from a single, hi8gh-density 5.25-inch floppy, but Hardware requirement depends upon Linux software & accessories selection.

Component                                      Minimum                                   Good Pe

Processor                                            386                                             Pentium 133

RAM                                                  4 MB                                          32 - 64 MB

Hard Disk                                          150 MB                                       IGB

Display  VGA, Mouse, CD-Rom

                      

Linux Tools & Applications:

The outermost layer of the Linux operating system is its tools and applications. These tools can be invoked from the command line itself and help perform the day-to-day as well as complex tasks of the system.

The Shell:

It is the command interpreter of the operating system. It accepts commands from users and analyses and interprets these commands.

The Linux Kernel:

It is the core of the system. It controls all the tasks, schedules all the processes and carries out all the crucial functions of the operating system. All operating systems have a kernel that contains thousands of routines to carry out the numerous tasks that the operating system has to handle. The major duties of the kernel are under:

1. To keep track of the programs that are executing
2. All processor time to each and also decide when one program stops and another starts.
3. It also handles exchange of information between computer and its terminals tape drives and printers.

Linux File System:

To store data in a computer system so that you can retrieve it at some time in the future, you place it in a file in the file system and give the file a filename so that you can reference it again later on. File are, stored on magnetic disk and hence continue to exit even if the computer is switched off and also set permission on it.
Linux distinguishes three types of files in its file system -
An ordinary file has no internal structure imposed on it by the system - it is simply a sequence of characters.
A directory file stores information about other files and directories. This enables Linux to organinse its file system into a hierarchy of files and directories.
The special files are the input/output devices attached to a particular computer system.

Important Directories in the Linux File System:

Most of the directories that hold Linux system files are "standard" some of the most important directories on your Linux system.

• /          
  This is the root directory. It holds the actual Linux program, as well as sub-directories. Do not store your own files here.
• /home   
  This directory holds users' home directories. After logging to the system this is PWD for a user.
• /bin       
  This directory holds many of the basic Linux programs. Bin stands for binaries, files that are executable and that hold text only computers could understand.
• /usr       
  This directory holds many other user-oriented directories. Like games, help files.
• /dev      
  Linux treats everything as a file! The /dev directory holds devices. These are special files that serve as gateways to physical computer components. For instance, if you copy to /dev/fd0, you are actually sending data to the system's floppy disk. You terminal is one of the /dev/tty files. Partitions on the hared drive are of the form /dev/hd0. Even the system's memory is a device! 
• /usr/sbin
  This directory holds system administration files. If you do an Is -1, you see that you must be the owner, root, to run these commands.
• /sbin
  This directory holds system files that are usually run automatically by the Linux system.
• /etc
  This directory and its sub-directories hold many of the Linux configuration files. These files are usually text and they can be edited to change the system's configuration.

 File & Directories:

A file as a container of information. Once information is stored in a file, it will remain there until it is changed or the file is removed from the system.
A Linux allows filenames to be up to 256 characters long. These characters can be lower and upper cases letters, numbers and other characters, usually the dash(-), the underscore (_) and the dot (.).

Directory:

Whenever a new user is created in the Linux system to use Linux, a directory is created for that user which has a unique name. This directory is called the home directory. When you login successfully, Linux makes your home directory the current directory and you are then ready to begin your session. You can also make and remove sub-directories.

File Naming Rules:

1. A file name must be 1 to 255 characters long.
2. All characters are legal except (/) which is used for separating directory levels and files.
3. Spaces and tabs must be quoted if used as a part of file name. Avoid using following characters:
   @      #     $     ^    &     *      ?     (     )   [     ]     {    }        /        \        !        ;        '           "       <     >
4. All (.) at the beginning of a file name hides it from Is command.
5. Upper and lower case characters are interpreted differently. TMP is different from tmp.
6. Do not use following at beginning of file name:
   +      -        =      _

Wildcards:

It matches any string with zero or more characters.
?   It matches any single character.
[characters] It matches any one of the character enclosed in [ ] c1 - c2 will match characters c1 through c2.
[!characters] It matches any one of characters not enclosed in [ ]
Example using wildcards:

1. IS *.db
   It displays all files ending with .db.
2. Is[0-9]*
   It displays all files beginning with a numbers.
3. Is [!0-9]*
   It displays all files not beginning with a number.
4. Is *.[bdfg]
   It displays all files ending with characters b, d, f or g.
5. Is!(m*)
   It displays all files not beginning with m.

THE SHEL

It is the command interpreter of the operating system. It accepts commands from users and analyses and interprets these commands. Most of the Linux commands are executable C programs. Shell interprets user commands and starts executing appropriate executable file. It then request kernel to carry out actual transfer of data which finally leads to output that is displayed of the screen of the terminal. Shell acts are mainly used with Linux:

1. Bourne Shell (sh):
   This is one of the most widely used shells in the Linux world. It was developed by Steve Bourne of AT&T Bell Laboratories in the late 1970's. It is the primary Linux command interpreter and comes along with every Unix system. It introduced many shell concepts such as the ability to text program for success of failure status, allows for sophisticated scripting (Programing) but lack of features such as history list and command line editing. The prompt used by the Bourne shell in the Linux installation is shown by a ($) dollar sign.
2. C Shel (Csh):
   The C shell was developed by Bill Joy at the University of California at Berkeley. The C shell is the default shell in the Berkeley version of Unix. It has a few principal advantages over the Bourne shell.
• A history mechanism:
  The C shell remembers the commands that the user types and allows him to recall them without having to retype them.
• Aliasing:
  The C shell permits you to call frequently used commands by your own formulated abbreviations. This is a type of "micro" facility that is available at the command line.
• Arithmetic:
  Arithmetic calculation and comparison, testing can be performed by the shell itself.
3. Korn Shel (Ksh):
   Developed by David Korn at AT&T, this shell was designed to be much bigger than the Bourne shell and includes several features that make it more superior. It includes all the enhancement of C shell like command history and aliasing and offers a few more features itself which makes it more efficient than the Bourne shell.
4. Broune Again Shell (Bash):
   It is the most common shell installed with Linux Distribution. It is based on Bourne Shell and provides additional feature set including command line editing, a history list and file name completion and allow to write sophisticated shell scripts using Bourne Shell like syntax.

WHAT IS DISTRIBUTION

Distribution is different sets of applications,  utilities, tools and drivers modules are built on same versions Kernel (the heart of the Operating System), can include and can offer different installation and upgrade programs to ease management of the system.
As windows 98 or Window NT defines the complete set of windows utilities applications and drivers that Microsoft ship. There is no room for variation in any application, drivers or utility.
But Linux has opened the door to different flavors of Linux meet differed need. On the same Kernel version they allow3 to add are remove applications, drivers and utility and allow3 to redistribute their product. Hence each product are called Distribution.
Following are the different types of Distributions.

1. Red Hat:Red Hot Linux distribution from Red Hat Software (www.redhat.com) has emerged as the favorite Linux distribution for most users. Red Hat gained fame for its tools for installation and upgrading the operating system. It introduce GNOME Desktop some feature are Improve installation, improved Administration Tools like LinuxConfig, Xconfigurator, GNOME Desktop environment for X Windows, improved performance features like Symmetrical Multiprocessing and offer different RAID Techniques.
2. Slack Ware:
   Before Red Hat Linux come to fame slack ware was the distribution to beet but still a popular distribution and found on (www.slakware.com) the distribution offers the full Range of expected utilities, tools, application, including X windows, development tools such as GNU computers Full Java Support and Java SDK for Linux. It can be downloaded Walnut Greek FTP site (ftp.cdram.com)
3. Debian:
   Debian has no commercial organisation backing it. It is produced by a team of volunteers. Debian offer more than 1000 software packages and publicised their bugs on website (www.debian.org). It is offer free distribution redistribution right, available source code.
4. Caldera Open Linux:
   This distribution can be downloaded at no cost from Caldera Website at (www.calerasystems.com). It include K desktop environment and non commercial Star office for Linux. Word Perfect 6 for Linux Netware support and license of DR-DOS for Dos compatibility.

INSTALLING LINUX (REDHAT)

Step by Step Guide to Installing Redhat

• Screen 1:
  If you have booted your system with the Redhat installation media or are installing by NFS you will see the Redhat welcome scree. Press enter for install in graphical mode.
• Screen 2:
  Press Next.
• Screen 3:
  For language select English.
• Screen 4:
  Keyboard type. Choose US International.
• Screen 5:
  Mous4e type. Select your mouse type here and if you are going to use this system as a desktop, enable the emulate 3 buttons check box.
• Screen 6:
  Installation type. Choose custom.
• Screen 7:
  Disk Partitioning. Choose Manually with Disk Drive.
• Screen 8:
  Disk setup. Delete all existing partitions (Warning: All Data currently on the disk is erased!) Depending on your needs, create new partitions. for simplicity, creating two partitions, one for use as swap which I make twice as large as the amount of physical RAM and one for all other data, called a root partition. Here's how;
  Select new then enter the following into the pop-up box;
  file system type swapsize (2x RAM) e.g. 64
  then OK
  then;
  Select new
  enter the following into the pop-up box;
  Mount Point /
  File system type EXT3
  and click the Fill to maximum  allowable size check box then click OK
  You should now have two visible partitions, called /dev/hdal.1 and /dev/hda2 underneath the /dev/hda entry. One will be type EXT3 and one will be type swap.
  At this stage will have finished configuring partitions. Click next to go to the next screen.
• Screen 9:
  Boot Loader. Grub is the preferred boot loader and the default options are suitable, so nothing needs to be changed here. Click Next. 
• Screen 10:
  Network configuration. You will see a list of your network interfaces (such as eth0). Configure each one to suit your own physical network requirements.
  here we don't use DHCP for wired machines so we select to configure manually and enter the IP information in the box provided.
  Note that your wireless card probably has not been detected by this stage. Do not worry will shell configure it later.
• Screen 11:
  Firewall configuration. If you intend to run NoCat your entries here will be superseded by the NoCat configuration process. For the purpose of the initial configuration, select Medium security level and ETH0 as a trusted device. Allow Incoming ssh.
• Screen 12:
  Additional Language Support. Select Other language from the list and uncheck English (USA).
• Screen 13:
  Time Zone. Click on the map of Pakistan to set the time zone.
• Screen 14:
  Root password. This screen is where we set the password for the super-user. Create a root password that you will remember. Click OK then Next.
• Screen 15:
  Authentication Configuration. The default settings don't need to be changed. Click Next.
• Screen 16:
  Package selection. The packages you choose here will depend on what you want to do with you system, so the recommendations we make below are guidelines. Anything that you omit here but need later can be installed at a later stage. Here it is section by section.;
  
  In Editors Emacs can be removed and vim-enhanced can be added.
  
  In Graphical Internet evolution, gaim, Mozilla-mail, pane and xchat can be remove.
  
  In Office/Productivity mrproject and open-office can be removed.
  
  In Sound and Video any selected packages in this section can be removed.
  
  In Graphics gimp, gimp-data-extras, gtkam, sane-frontends, xsane and xsane-gimp can be removed.
  
  In Server Configuration Tools select all of the GUI configuration tools you require for the various services you intend to have on the box. You may find redhat-config-bind, redhat-config-httpd, redhat-config-network and redhat-config-services useful.
  
  In Web Server select all that are applicable for you situation if you intend to use this system as a web server in addition to an Access Point. For use with NoCat you will need mod_perl and mod_ssl.
  
  In Network Servers select all of the services you wish to run. For our Access Point we need ZEBRA and DHCP cipe, pxe, rsh-server, talk-server, telnet-server and ypserv can be removed.
  
  In Administration Tools select all of the GUI config tools that you think you require. They are safe to install even if you don't end up using them.
  
  In System Tools amanda, ethereal, etheral-gnome, nmap and nmap-front-end are useful and can be installed and we will use shapecfg in appendix C for configuring bandwidth management. Click next to being the actual RedHat installation. The install process will begin by formatting the new partitions and installing the various packages required for a functioning Linux system. The installation should take approximately 25 minutes. At the end of this process, configure the X display system for you hardware if required. It is a good idea to turn off Graphical login type at this point. You will be presented with the option to create a boot disk once the installe is complete. It is good idea to do so.

 Tuning off Unnecessary Services 

One last job remains; after you have logged into your system and are satisfied that it is working correctly, we'll turn off some of the plethora of services and Redhat has enabled. Some of these services we will enable later but in the mean time they are using system boots, both of which are inconvenient while we are building and testing our new system.
You can manually turn off services by re-naming files in the /ect/rc.d/ hierarchy, but Redhat has a menu driven system called simply setup that is easier use. Access it with this command;

[root@accesspoint root]# setup

A menu will come up. Scroll down to System Services and press enter to select it. You will see a list to services, those with an asterix are enabled. Disable the following services by highlighting the asterix and pressing the space bar.

anacron Scheduling daemon

apmd Power management daemon 

atd Scheduling daemon

autofs Auto-mounting of remote file systems

cups Unix print daemon

gpm Console mouse support daemon

isdn iisdn

iptables Firewalling

kudzu Hardware maintenance daemon

netfs Remote file system mounter daemon

nfslock Network File System daemon

pcmcia PCMCIA monitor daemon

portmap RPC control daemon

rhnsd Redhat update daemon

Sendmail Mail server daemon

xinetd TCP/IP se4rvices supe-daemon

This leave us with only these services enabled; crond, keytable, network, random, rawdevices, sgi_fam, sshd, syslog & xfs which will make the system more responsive. Note that xfs, the X font server, can be disabled as well if you have no intention of running X.

Reboot & Test

You may like to reboot your system now to make sure that it comes back up OK. Reboot with this command;

[root@accesspoint root]# shutdown-r now

Once your system comes back up and you are satisfied that it is functioning nominally.

LINUX Files System Management

• badblocks:
  Used to search a disk or partition for badblocks.
• efdisk:
  Similar to fdisk but with nicer interface.
• debugfs:
  Allows direct access to filesystems data sturcture.
• df:
  Shows the disk free space on one4 or more filesystems.
• dosfsck:
  Check and repair MS-Dos filesystems.
• du:
  Shows how much disk space a directory and all its files contain.
• dump:
  Used to back up an ext2 filesystem. Complement is restore.
• dumpe2fs:
  Dump filesystem superblock and bolcks group information. Ex: dump32fs/dev/hda2.
• e2fsck:
  Check a Linux sound extended file system.
• e2label:
  Change the label on an ext2 file system.
• exportfs:
  Used to set up file system to export for nfs (network file sharing).
• fdisk:
  Used to fix or create partitions on a hard drive.
• fdformat:
  Formats a floppy disk.
• fsck:
  Used to add new blocks to a file system. Must not be run on a mounted file system.
• hdparm:
  Get set hard disk geometry parameters, cylinders, heads sectors.
• mkfs:
  Initialises a Linux file system. This is a front end that runs a separate program depending on the file system's type.
• mke2fs:
  Create a Linux second extended file system.
• mkswap:
  Sets up a Linux swap area on a device or file.
• mount:
  Used to mount a filesystem. Complement is amount.
• rdev:
  Query / set image root device, swap device, RAM disk size of video mode. What this does is code the device containing the root filesystem into the kernel image specified.
• rdump:
  Same as dump.
• rmt:
  Remove magtape protocol module.
• restore:
  Used to restore an ext2 filesystem.
• setfdprm:
  Set floppy drive parameters.
• swapoff(8):
  Used to deactivate a swap partition.
• swapon(8):
  Used to activate a swap partition.
• sync:
  Forces all unwritten blocks in the buffer cache to be written to disk.
• tune2fs:
  Adjust tunable filesystem parameters on second extended filesystem.
• umount:
  Unmounts a filesystem. Complement is mount.

Creating a User Account

When you first start your Red Hat Enterprise Linux system after installation, you were given the opportunity to create one or more user accounts using the Setup Agent. If you did not create at least one account (not including the root account) you should do so now. You should avoid working in the root account for daily tasks.

There are two ways to create new and/or additional user account: using the graphical User Manager application or from a shell prompt.

To create a user account graphically using the User Manager:

1. Select Applications (the main menu on the panel) => System Setting => Users & Groups from the panel. You can also start the User Manager by typing redhat-config-users at a shell prompt.
2. If you are not logged is as root, you will be prompted for your root password.
3. The window will appear. Click Add User.
4. In the  Create New User dialog box, enter a username (this can be an abbreviation or nickname), the full name of the user for whom this account is being created and a password (which you will enter a second time for verification). The name of this user's home directory and the name of the login shell should appear by default. For most users, you can  accept the defaults for the other configuration options. Refer to the Red Hat Enterprise Linux system Administration Guide for detail about additional options.
5. Click OK. The new user will appear in the user list, signaling that the user account creation is complete.

To create a use account from a shell prompt:

1. Open a shell prompt.
2. If you are not logged in as root, type the command su - and enter the rot password.
3. Type useradd followed by a space and the username for the new account you are creating at the command line (for example, useradd khan2015). Press [Enter]. Often, usernames are variations on the user's name, such as adkhan2015for Adnan Khan. User account name can be anything from the user's name, initials or birthplace to something more creative.
4. Type password followed by a space and the username again (for example, password adkhan2015).
5. At the new password: prompt enter a password for the new user and press [Enter].
6. At the retype new password: prompt, enter the same password to confirm your selection.

How To Add a New User in Redhat

To add a user and set up the directories you want that user to have, user the useradd command. By default, this will add a user and create a home directory for that user, which will be located in /home.
EXAMPLE: /usr/sbin/useradd yourname will create the user yourname, and make the directory /home/yourname.
EXAMPLE: /ur/bin/passwd yourname. You will be prompted twice for a password.
NOTE: If you wand useradd to create more default directories than just /home/newuser, you can add then to /etc/skel. Anything you add to this directory will be created when you add a new user.
EXAMPLE: mkdir/etc/skel/www will add a directory called www to the skel dir. Now whenever you run useradd to create a new user, it will also create a www direcrtory in the new users home directory.
There are also some options for useradd you can if you wish, such as changing where the users home directory will be or which skeleton directory to use.