Home > GE2155 computer lab > GE 2155 – COMPUTER PRACTICE LABORATORY




1. UNIX COMMANDS                                 15

Study of UNIX OS – Basic Shell Commands – Unix Editor

2. SHELL PROGRAMMING                             15

Simple Shell program – Conditional Statements – Testing and Loops

3. C PROGRAMMING ON UNIX                         15

Dynamic Storage Allocation-Pointers-Functions-File Handling



  1. 1 UNIX Clone Server
  2. 33 Nodes (thin client or PCs)
  3. Printer – 3 Nos.


  1. OS – UNIX Clone (33 user license or License free Linux)
  2. Compiler – C





List of experiments

Sl. No

Name of the Experiments

Page No.

1 Study of UNIX Operating system
2 Study of Basic Shell Commands
3 Study of UNIX vi editor
  1. Write a shell program to find sum and product for the given two numbers.
  2. Write a shell program to check whether the given number is odd or even.
  3. Write a shell program to generate student mark details.
  1. Write a shell program to perform arithmetic operations.
  2. Write a shell program to read N numbers from the user with command line arguments and display its sum.
  3. Write a shell program to find the sum of first N natural numbers.
  1. Write a shell program to find the factorial of a given numbers.
  2. Write a shell program to generate Fibonacci Series.
  3. Write a shell program to count the number of vowels in the given String.
  1. Write a C program to perform linear search using function.
  2. Write a C program to perform binary search using function.
  1. Write a C program to print the elements of an array using pointers.
  2. Write a C program to find the length of the string.
  1. Write a C program to concatenate two strings.
  2. Write a C program to copy the contents of one string to another.
  1. Write a C program to copy the contents of one file to another.
  2. Write a C program to count the characters and lines in a file.

Study of UNIX OS

EX. NO. :


AIM: To study the UNIX OS.

What is UNIX?

UNIX is an operating system which was first developed in the 1960s, and has been under constant development ever since. By operating system, we mean the suite of programs which make the computer work. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops.

UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy to use environment. However, knowledge of UNIX is required for operations which aren’t covered by a graphical program, or for when there is no windows interface available, for example, in a telnet session.

Types of UNIX

There are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, and MacOS X.

The UNIX operating system

The UNIX operating system is made up of three parts; the kernel, the shell and the programs.

The kernel

The kernel of UNIX is the hub of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to system calls.

As an illustration of the way that the shell and the kernel work together, suppose a user types rm myfile (which has the effect of removing the file myfile). The shell searches the filestore for the file containing the program rm, and then requests the kernel, through system calls, to execute the program rm on myfile. When the process rm myfile has finished running, the shell then returns the UNIX prompt % to the user, indicating that it is waiting for further commands.

The shell

The shell acts as an interface between the user and the kernel. When a user logs in, the login program checks the username and password, and then starts another program called the shell. The shell is a command line interpreter (CLI). It interprets the commands the user types in and arranges for them to be carried out. The commands are themselves programs: when they terminate, the shell gives the user another prompt (% on our systems).

The adept user can customise his/her own shell, and users can use different shells on the same machine. Staff and students in the school have the tcsh shell by default.

The tcsh shell has certain features to help the user inputting commands.

Filename Completion – By typing part of the name of a command, filename or directory and pressing the [Tab] key, the tcsh shell will complete the rest of the name automatically. If the shell finds more than one name beginning with those letters you have typed, it will beep, prompting you to type a few more letters before pressing the tab key again.

History – The shell keeps a list of the commands you have typed in. If you need to repeat a command, use the cursor keys to scroll up and down the list or type history for a list of previous commands.

Files and processes

Everything in UNIX is either a file or a process.

A process is an executing program identified by a unique PID (process identifier).

A file is a collection of data. They are created by users using text editors, running compilers etc.

Examples of files:

  • a document (report, essay etc.)
  • the text of a program written in some high-level programming language
  • instructions comprehensible directly to the machine and incomprehensible to a casual user, for example, a collection of binary digits (an executable or binary file);
  • a directory, containing information about its contents, which may be a mixture of other directories (subdirectories) and ordinary files.

The Directory Structure

All the files are grouped together in the directory structure. The file-system is arranged in a hierarchical structure, like an inverted tree. The top of the hierarchy is traditionally called root (written as a slash / )

Most UNIX file system types have a similar general structure, although the exact details vary quite a bit. The central concepts are superblock, inode, data block, directory block, and indirection block. The superblock contains information about the file system as a whole, such as its size (the exact information here depends on the file system). An inode contains all information about a file, except its name. The name is stored in the directory, together with the number of the inode. A directory entry consists of a filename and the number of the inode which represents the file. The inode contains the numbers of several data blocks, which are used to store the data in the file. There is space only for a few data block numbers in the inode, however, and if more are needed, more space for pointers to the data blocks is allocated dynamically. These dynamically allocated blocks are indirect blocks; the name indicates that in order to find the data block, one has to find its number in the indirect block first.

Like UNIX, Linux chooses to have a single hierarchical directory structure. Everything starts from the root directory, represented by /, and then expands into sub-directories instead of having so-called ‘drives’. In the Windows environment, one may put one’s files almost anywhere: on C drive, D drive, E drive etc. Such a file system is called a hierarchical structure and is managed by the programs themselves (program directories), not by the operating system. On the other hand, Linux sorts directories descending from the root directory / according to their importance to the boot process.

Linux, like Unix also chooses to be case sensitive. What this means is that the case, whether in capitals or not, of the characters becomes very important. This feature accounts for a fairly large proportion of problems for new users especially during file transfer operations whether it may be via removable disk media such as floppy disk or over the wire by way of FTP.

The image below shows the file system of Linux

The following bin/ dev/ home/ lost+found/ proc/ sbin/ usr/ boot/ etc/ lib/ mnt/ root/ tmp/ var/ are explained in detail.

/sbin – This directory contains all the binaries that are essential to the working of the system. These include system administration as well as maintenance and hardware configuration programs.

/bin – In contrast to /sbin, the bin directory contains several useful commands that are used by both the system administrator as well as non-privileged users.

/boot – This directory contains the system.map file as well as the Linux kernel. Lilo places the boot sector backups in this directory.

/dev – This is a very interesting directory that highlights one important characteristic of the Linux filesystem – everything is a file or a directory. Look through this directory and you should see hda1, hda2 etc, which represent the various partitions on the first master drive of the system. /dev/cdrom and /dev/fd0 represent your CDROM drive and your floppy drive.

/etc – This directory contains all the configuration files for your system. Your lilo.conf file lies in this directory as does hosts, resolv.conf and fstab.

/home –These are the user home directories, which can be found under /home/username.

/lib – This contains all the shared libraries that are required by system programs. Windows equivalent to a shared library would be a DLL file.

/lost+found – Linux should always go through a proper shutdown. Sometimes your system might crash or a power failure might take the machine down. Either way, at the next boot, a lengthy filesystem check using fsck will be done. Fsck will go through the system and try to recover any corrupt files that it finds. The result of this recovery operation will be placed in this directory.

/mnt – This directory usually contains mount points or sub-directories where you mount your floppy and your CD.

/opt – This directory contains all the software and add-on packages that are not part of the default installation.

/proc – This is a special directory on your system.

/root – We talked about user home directories earlier and well this one is the home directory of the user root.

/tmp – This directory contains mostly files that are required temporarily.

/usr – This is one of the most important directories in the system as it contains all the user binaries. /usr/src/linux contains the source code for the Linux kernel.

/var – This directory contains spooling data like mail and also the output from the printer daemon. The above content briefs about Linux and the file system of Linux.


EX. NO. :


AIM: To study the basic commands in UNIX.


1. TASK : To display the system date and time.

COMMAND     : date.

SYNTAX : date.

EXPLANATION: This command displays the current system date and time on the



2. TASK : To display the current month.

COMMAND : date.

SYNTAX      : date +%m.

EXPLANATION: This command displays the current month on the screen.


3. TASK : To display the name of the current month.

COMMAND : date.

SYNTAX : date +%h.

EXPLANATION: This command displays the name of the current month on the



4. TASK : To display the current system date.

COMMAND : date.

SYNTAX : date +%d.

EXPLANATION: This command displays the current system date on the screen.


5. TASK : To display the current system date (year).

COMMAND : date.

SYNTAX : date +%y.

EXPLANATION: This command displays the current year on the screen.


6. TASK : To display the current system time.

COMMAND : date.

SYNTAX : date +%H.

EXPLANATION: This command displays the current system time (in hours) on the



7. TASK : To display the current system time.

COMMAND : date.

SYNTAX : date +%M.

EXPLANATION: This command displays the current system time (in minutes) on the screen.


8. TASK : To display the current system time.

COMMAND : date.

SYNTAX : date +%S.

EXPLANATION: This command displays the current system time (in seconds) on the screen.


9. TASK : To display the calendar of the current month.

COMMAND : calendar.

SYNTAX : cal.

EXPLANATION: This command displays the calendar of the current month on the



10. TASK : To display user-defined message.

COMMAND : echo.

SYNTAX : echo “message”.

EXPLANATION: This command displays on the screen the argument of the echo



11. TASK : To display the details of all users.

COMMAND : who.

SYNTAX : who.

EXPLANATION : This command lists the information about all the users who have

logged on to that system.


12. TASK : To display the user detail.

COMMAND : who.

SYNTAX : whoami.

EXPLANATION : This command displays information about the current user of the

system on the screen.


13. TASK : To create a directory.

COMMAND : make directory.

SYNTAX : mkdir.

EXPLANATION : This command is used to create a new directory with the specified




14. TASK : To change directory.

COMMAND : change directory.

cd directory name.

EXPLANATION : This command is used to switch from one directory to another.



15. TASK : To delete a directory.

COMMAND : remove directory.

rmdir directory name

EXPLANATION : This command is used to delete the specified directory.



16. TASK : To come out of a sub-directory.

COMMAND : change directory.

SYNTAX : cd ..

EXPLANATION : This command helps in switching to the main directory.


17. TASK : To list all the files and directories.

COMMAND : list.


EXPLANATION : This command displays all the files and directories of the system.


18. TASK : To create a file.

COMMAND : cat.

cat> file name.

EXPLANATION : This command leads to the creation of a new file with the specified

file name and contents.



19. TASK : To view a file.

COMMAND : cat.

cat file name.

EXPLANATION : This command displays the contents of the specified file.



20. TASK : To copy a file.

COMMAND : copy.

cp sourcefile destinationfile.

EXPLANATION : This command produces a copy of the source file and is stored in

the specified destination file by overwriting its previous




21. TASK : To move a file.

COMMAND : move.

mv sourcefile destinationfile.

EXPLANATION : After moving the contents of the source file into destination file,

the source file is deleted.



22. TASK : To display / cut a column from a file.

COMMAND : cut.

cut –c no. filename.

EXPLANATION : This command displays the characters of a particular column in the

specified file.




23. TASK : To delete a file.

COMMAND : remove.

rm file name.

EXPLANATION : This command deletes the specified file from the directory.



24. TASK : To retrieve a part of a file.

COMMAND : head.

head –no. of rows file name.

EXPLANATION : This command displays the specified no. of rows form the top

of the specified file.



25. TASK : To retrieve a file.

COMMAND : tail.

SYNTAX : tail –no. of rows file name.

EXPLANATION : This command displays the specified no. of rows form the bottom

of the specified file.



26. TASK : To sort the contents of a file.

COMMAND : sort.

sort file name.

EXPLANATION : This command helps in sorting the contents of a file in ascending





27. TASK : To display the no. of characters in a file.

COMMAND : word count.

wc file name.

EXPLANATION : This command displays on the screen the no. of rows, words, and

the sum of no. of characters and words.



28. TASK : To display the calendar of a year.

COMMAND : cal.

cal year.

EXPLANATION : This command displays on the screen the calendar of the specified                      year.



Listing Directory Contents

1. Log in to the system.

2. Issue the command pwd . What is the path?


3. Issue the command ls. What do you observe?


4. Issue the command ls –l . In an abbreviated form, what do you observe?



5. Issue the command ls –a. In an abbreviated form, what do you observe?



6. Issue the command cd /var.

7. Issue the command pwd . What is the path?


8. Issue the command ls. What do you observe?


9. Issue the command ls –l . In an abbreviated form, what do you observe?


10. Issue the command ls –a. In an abbreviated form, what do you observe?


11. Issue the command ls – i . Record the inode value for each file and directory. inode filename inode filename




In your own words, explain the meaning of:

1. The Root


2. Administrator Root


3. Home directory Root


4. Group Root


5. What is the difference between the user root and group root.


  1. Beside the UNIX commands below, define what each command does.

Frequently used UNIX commands

Command Result
ls lists files in current working directory
ls *.out lists all files in current directory that end in .out
ls -l lists files giving details including file size
pwd displays full-path name of your current working directory on screen (stands for “present working directory”)
cd dirname changes directory to dirname
cd .. changes directory to one above the current directory
cd with no argument, takes you to your home directory
mkdir dirname creates new directory dirname
rmdir dirname removes empty directory dirname
cp filename newname makes a copy of filename with the name newname
cp ../filename . copies filename in directory one tier above to current directory giving it the same name
mv filename newname renames filename to newname (mv stands for “move”)
cat filename displays contents of filename on screen
more filename displays filename contents one screen at a time (Enter key scrolls through file by line; space bar scrolls through by screen)
head filename displays first 10 lines of filename on screen
tail filename displays last 10 lines of filename on screen
rm filename deletes filename
without double check (rm stands for “remove”)
grep string filename displays lines from filename containing string on screen
./ filename & runs job filename in the background
qsub filename sends job filename to queue (where qsub is a submission script file in your bin directory)
qstat lists jobs running on queue
qstat -a lists only your jobs
qdel job# deletes job with number job# from queue
ps lists processes you have running
ps -ef lists all processes
kill pid# kills process with ID number pid#
kill -9 pid# kills (with the “sure kill” signal) process with ID number pid#
kill -kill 0 kills all processes you have running and logs you off
man commandname displays manual page for command commandname
man -k keyword lists manual pages for commands related to keyword
lp filename prints filename on printer in room 4241
chmod ### filename changes “read, write, execute” mode of filename

Example: to set the privileges for filename so that the owner has the ability to read, overwrite and execute the file, the group has the ability to read and execute the file, and everyone else has no access to the file, use the command chmod 750 filename.







4 2 1

4 2 1

4 2 1

sum numbers for each of the three categories of user
Ctrl+c kills current operation
Ctrl+h delete (always works even when delete key doesn’t)
Ctrl+d logout

UNIX: vi Editor

EX. NO. :


AIM: To study the basic of vi Editor.

UNIX: vi Editor

General Introduction

The vi editor (short for visual editor) is a screen editor which is available on almost all Unix systems. Once you have learned vi, you will find that it is a fast and powerful editor. vi has no menus but instead uses combinations of keystrokes in order to accomplish commands.

There are three basic modes of vi:

Command mode

This is the default when you enter vi. In command mode, most letters, or short sequences of letters, that you type will be interpreted as commands, without explicitly pressing Enter
. If you press Esc when you’re in command mode, your terminal will beep at you. This is a very good way to tell when you’re in command mode.

Insert mode

In insert mode, whatever you type is inserted in the file at the cursor position. Type a (lowercase letter a, for append) to enter insert mode from command mode; press Esc to end insert mode, and return to command mode.

Line mode

Use line mode to enter line oriented commands. To enter line mode from command mode, type a colon ( : ). Your cursor moves to the bottom of the screen, by a colon prompt. Type a line mode command, then press Enter. Any sensible command from the Unix line editor ex will work, and a few are good to know about. These commands are indicated in this handout by a colon in front of the command. Each time you use a line mode command, you must type a colon to enter line mode, then type the command by the colon prompt at the bottom of the screen, then press Enter when you finish typing the command. (The search commands starting with / and ? work similarly.

General Command Information

As mentioned previously, vi uses letters as commands. It is important to note that in general vi commands:

You will see some commands which start with a colon (:). These commands are ex commands which are used by the ex editor. ex is the true editor which lies underneath vi — in other words, vi is the interface for the ex editor.

  1. The vi editor has three modes: 1) command mode, 2) last-line mode, and 3) input mode. Note: The vi editor does not understand the “mouse” and only understands commands typed from the “keyboard.”
  1. The UNIX text editor, vi, is used by the UNIX administrator (superuser) to create or edit files. Usually these files require configuration information to host certain UNIX servers or I/O functions. Users can start a vi session by typing “vi” followed by the file name to be created or edited. In our example, we will create a file named “linux.” The vi editor will create a new file if the file does not already exist. If a file, in our example “linux,” does exist in our current directory, the vi editor will open linux for editing. Once we type ” vi linux” and hit the enter key, we are placed in command mode where communications is directed to the vi editor. Type the following command to initiate our vi session:

vi linux <enter>

  1. You will be presented with a full, empty screen. Each line will begin with the tilde (~) symbol. The tilde is vi’s way of indicating that a line is empty in its edit register. The vi editor uses the first 24 of 25 lines viewable on the terminal screen as “insert lines.”
  1. The last line (line number 25) is used for entering commands to the shell and is referred to as the “last-line mode.” In this space, our filename appears with the message “linux” and [new file].
  1. When you open a file, the cursor is placed at the top, left corner of the screen. You are said to be in “Command Mode.” You can issue commands that act upon the text in the file. In the command mode, pressing a key does not show on the screen, but performs a function like moving the cursor to the next line or deleting a line. The command mode cannot be used to enter text. The keyboard space bar moves the cursor ahead one space at a time. The keyboard backspace key moves the cursor backwards one space at a time.
  1. To enter text, you must be in “Insert Mode.” There are ten (10) keys that place you in Insert Mode. Each key has an upper case and a lower case function. The quickest way to learn insert mode is to simply type a lower case “i” for insert. The following chart the shows 10 ways to enter “Insert Mode:”



i Inserts text to left of the cursor. Existing text shifted right
I Inserts text at beginning of line. Existing text shifted right
a Appends text to right of the cursor. Existing text shifted right
A Inserts text at end of the line
o Opens a line below the current line the cursor is on
O Opens line above the current line the cursor is on
rch Replaces a single character (ch) under cursor. No [Esc] required
R Replaces text from cursor to right. Existing text overwritten
s Replaces character under cursor with any number of characters
S Replaces entire line that cursor is on


To exit input mode, you must enter the [Esc] key.

  1. The Last-line Mode is opened by pressing and holding the [shift] key and the [:] colon key simultaneously ([shift] + [colon]). If this fails to place you in “Last-line” mode, hit the escape <esc> key to move from insert mode to command mode. Upon entering this dual key-stroke combination, the cursor moves to the bottom, left corner of the screen and appears as a colon “:” . This mode allows the vi user to send commands to the actual UNIX shell. Commands used in the “Last-line Mode” write the contents of a file to the hard drive, reads contents into the existing file from another file, or quits the vi session. Once a command has been executed, the cursor moves back to the top, left of the screen. To move back to the top of the screen without executing a command, press the <esc> key. While in last-line mode (where we communicate with the shell and not with the vi editor), the following commands can be executed:

Last-line commands used to communicate with the UNIX/Linux shell:

Command Function
:w Writes file to hard drive and remains in editing mode
😡 Writes file and quits editing mode
:wq Writes file and quits editing mode
:q Quits editing mode with no changes made to file
:q! Forces vi to quit and exits to the command-line shell
:w >> note1 Appends current file contents to new file, note1
:r <filename> Reads contents of <filename> into current vi file
:n1, n2w customer.sql Writes selected lines, n1 through n2, to customer.sql
:.w customer.sql Writes current line [.] to file, customer.sql
:$w customer.sql Writes last line [$] to file, customer.sql
:! Used to execute a shell command without leaving vi
[Crtl-z] Suspends current session and escaped to UNIX shell

  1. Let’s begin our next lab exercise by opening an empty file named “linux” and manually inserting a script entitled, The Linux Story.

Note: The vi editor does not perform an automatic word-wrap, so hit the <enter> key at the end of a normal line (80 characters). This will help with editing features, perform a carriage feed, and begin a new line.

While you are entering “The Linux Story,” periodically write the file to the hard drive by typing <esc> and then entering the last-line command <SHIFT> + <:>. A colon appears at the bottom, left of the screen. Enter w and press <enter>. If a file fails to write, use <SHIFT>+<:> plus the ! symbol, such as :w! . The bang sign ( ! ) forces a write to the hard drive.

The linux Story

Linus Torvalds, creator of the Linux Operating System, was born Dec 28, 1969 in Helsinki, Finland. His grandfather had a Commodore VIC-20 that he had the opportunity to work with; by age ten he was already dabbling in programming. He enrolled at the University of Helsinki in 1989, and in 1990 he took his first C programming class.

( after entering the above information, write and quit vi by :wq! )

Note: Since vi places its text in a buffer, it is wise to frequently write a file to disk at specific intervals. This will prevent data loss if the system fails or an incorrect key combination closes our file. Saving the buffer is performed in the last-line mode. Every command in this mode is preceded by a : (colon) and followed by the <enter> key. To save, enter last-line mode and then enter w (for write) and press the enter key.

  1. Opening a new line: place the cursor on the main title, The Linux Story, and open a new line underneath the title by typing a lower case o. You can now enter, By Anonymous. Since the o placed you in the Insert Mode, you must enter [Esc] to return to the Command Mode.
  1. Replacing text: replacing text can be done by one character at a time or a string of characters at a time. Use the r, R, s, and S keys. Place the cursor over the l in linux in the first line. Now hit the r key and then type an upper case L. This changes the word linux to Linux.

Note: vi momentarily switches from the Command Mode to the Insert Mode when r is pressed and back to the Command Mode as soon as the character is entered.

  1. Replacing a word: replacing a word can be done using the cw (change word) command. Place the cursor on the letter D where Linus’ birthday is shown as “Dec”. Now, type cw. Dec should disappear. Now type December. This changes the word Dec to December. Press the Escape <esc> key.
  1. Replacing a single character with multi-character text: use the s key after placing the cursor at the beginning of the word string to be replaced.
  1. Replacing an entire line with another line: use the S key after placing the cursor at the beginning, or at any point, of the sentence to be replaced.
  1. Determining your current cursor position by line number: use the [Ctrl-g] key to see what line number your cursor is on. The line number is displayed in the last-line position at the bottom right of the screen.
  1. Placing the cursor on a predetermined line: Use the G key followed by a line number to place the cursor on a particular line (While in Command Mode enter, 12G to go to the 12th line).
  1. Moving the cursor from the beginning of or to the end of the current line: enter a caret (^) to move to the beginning of the current line or enter a dollar ($) to move to the end of the current line.
  1. Moving around in a document: Use the up-down, right-left keyboard keys or use b, e, and w to move between words in a sentence.
  1. Deleting a character: use x to delete a character.
  1. Deleting an entire line: use dd to delete the entire current line.
  1. Undoing a mistake: Use the u to undo a key sequence mistake.
  1. Searching for a pattern string of characters: use the / (forward slash) followed by the pattern being searched for. To find the first occurrence of the word Linux, type /Linux and press <Enter>. Using ? instead of / will search backwards.
  1. Searching and replacing a string pattern: enter the last-line mode and type: 1,$s/pattern1/pattern2/ where 1 indicates the first line of the file and $ indicates the last line of the file. Pattern1 is the string searched for and pattern2 is the string replacing pattern1. To practice this important editing function, enter the Last-Line Mode [:] and type 1,$s/Story/Song/ and [Enter].
  1. Undo Song and change it back to Story by hitting [esc] and then u.
  1. Exit out of vi by entering the last-line mode and typing wq!
  1. Name the three modes used with the vi text editor.
  1. List the 10 ways to be placed in the Insert Mode using vi.
  1. Show the key-stoke sequence used to enter the Last-Line Mode using vi.
  1. In vi, which letter can be used to undo an editing mistake?
  1. In vi, what does the dd command do?

Editing Files

1. Log on to the system.

2. At the moment we need to create a new directory and then change to it. Issue the command:

mkdir /lab

Then change to the /lab directory.

3. Note your location.

Prompt: ____________________________________________________________

Full working Path: ____________________________________________________

4. Issue the command touch testfile.

5. Issue the command ls –l testfile. Record the results of the display.

Filename: ___________________________________________________________

File Attributes: ________________________________________________________

File Owner: ___________________________________________________________

File Group: ___________________________________________________________

File Size: _____________________________________________________________

File Creation Date: _____________________________________________________

6. Issue the command vi testfile2. You have now opened the vi editor to a new file called testfile2. You are in the command mode. Enter the command the letter ” i “. You are now in the insert mode, able to type in text.

7. Enter the following text:

Name: {your name}

IP Address: {your system IP address}

File: testfile2 using vi

I am a great student and am working hard to prove myself as

an A student!

8. Strike the ESC key. This places you into the command mode. If you hear additional beeps from the (small) computer speaker, you are already in the command mode.

9. Enter the command ” :w “. This saves the text to the hard drive.

10. Enter the command ” :q “. This exits the vi editor.

11. Enter the command vi testfile3.

12. Enter the following text:

Name: {your name}

IP Address: {your system IP address}

File: testfile3 using pico

My classmates are great people too.

13. List the contents of the directory. Record the results.

1. Log onto the system.

2. What is the path? ______________________________________________

3. Change to the /lab directory ( create the lab directory)

4. Record the full path of the directory. (if it is not /lab, you made an error)


5. Using the vi text editor, create a new file called test1.

6. Insert into the test1 file the following:

Test file 1.

My name is {your name}.

I am learning Linux.

7. Save the file (look at the bottom of the screen to WriteOut the file). Then exit.

8. Using the vi text editor, create a new file called test2.

9. Insert into the test2 file the following:

Test file 2.

Created by {your name}.

This is a simple file.

10. Save the file and exit.

11. Issue the command cat test1 . Record what you observe.


12. Issue the command cat test2 . Record what you observe.


13. Issue the command cat test1 test2 . Record what you observe.


14. Issue the command more test1 . Record what you observe.


15. Issue the command history | more . Scroll down through the file. Try to scroll up. (Note that only the space bar will scroll through the file. The ” | “, or pipe, will be dicussed later.) Record what you observe.


16. Issue the command less test2 . Record what you observe.


17. Issue the command history | less . Scroll up and down through the file using both the Up / Down Arrow keys and the Page Up / Down keys.

18. Issue the command history | head . Record what you observe.


19. Issue the command history | tail . Record what you observe.


20. Issue the command history | tac . Record what you observe.


21. Issue the command cat > test3 and hit ENTER.

22. Enter the following lines:

Test file 3.

Created by {your name}.

Created using the cat command.

{on this line, enter a CTRL-D}

23. Display the file with the cat command, record your observations.


Case Study

1. Test to see if the two files (test1 and test2) may be displayed by different display utilities.

Discuss your findings.

2. Compare the differences between the output of the following:

cat –E testfile3

cat –n testfile3

hexdump –c testfile3

od –ta testfile3

od –tc testfile3

xxd testfile3

Record your observations:

Moving One Character at a Time

Try using your direction keys to move up, down, left and right in your file. Sometimes, you may find that the direction keys don’t work. If that is the case, to move the cursor one character at the time, you may use the h, j, k, and l keys. These keys move you in the following directions:

h    left one space        l    right one space
j    down one space        k    up one space

If you move the cursor as far as you can in any direction, you may see a screen flash or hear a beep.

Moving among Words and Lines

While these four keys (or your direction keys) can move you just about anywhere you want to go in your file, there are some shortcut keys that you can use to move a little more quickly through a document. To move more quickly among words, you might use the following:

w    moves the cursor forward one word 
b    moves the cursor backward one word (if in the middle of a
     word, b will move you to the beginning of the current word).
e    moves to the end of a word.

To build on this further, you can precede these commands with a number for greater movement. For example, 5w would move you forward five words; 12b would move you backwards twelve words. [You can also use numbers with the commands mentioned earlier. For example, 5j would move you down 5 characters.]


Two short cuts for moving quickly on a line include the $ and the 0 (zero) keys. The $ key will move you to the end of a line, while the 0 will move you quickly to the beginning of a line.

Screen Movement

To move the cursor to a line within your current screen use the following keys:

H    moves the cursor to the top line of the screen.
M    moves the cursor to the middle line of the screen.
L    moves the cursor to the last line of the screen.

To scroll through the file and see other screens use:

ctrl-f    scrolls down one screen
ctrl-b    scrolls up one screen
ctrl-u    scrolls up a half a screen
ctrl-d    scrolls down a half a screen

Two other useful commands for moving quickly from one end to the other of a document are G to move to the end of the file and 1G to move to the beginning of the file. If you precede G with a number, you can move to a specific line in the document (e.g. 15G would move you to line 15).

Moving by Searching

One method for moving quickly to a particular spot in your file is to search for specific text. When you are in command mode, type a / followed the text you wish to search for. When you press Return, the cursor will move to the first incidence of that string of text. You can repeat the search by typing n or search in a backwards direction by using N.

Deleting (or Cutting) Characters, Words, and Lines

To delete a character, first place your cursor on that character. Then, you may use any of the following commands:

x    deletes the character under the cursor.
X    deletes the character to the left of your cursor.
dw    deletes from the character selected to the end of the word.
dd    deletes all the current line.
D    deletes from the current character to the end of the line.

Preceding the command with a number will delete multiple characters. For example, 10x will delete the character selected and the next 9 characters; 10X will delete the 10 characters to the left of the currently selected character. The command 5dw will delete 5 words, while 4dd deletes four lines.

Pasting Text using Put

Often, when you delete or cut text, you may wish to reinsert it in another location of the document. The Put command will paste in the last portion of text that was deleted since deleted text is stored in a buffer. To use this command, place the cursor where you wish the deleted text to appear. Then use p to reinsert the text. If you are inserting a line or paragraph use the lower case p to insert on the line below the cursor or upper case P to place in on the line above the cursor.

Copying Text with Yank

If you wish to make a duplicate copy of existing text, you may use the yank and put commands to accomplish this function. Yank copies the selected text into a buffer and holds it until another yank or deletion occurs. Yank is usually used in combination with a word or line object such as the ones shown below:

yw    copies a word into a buffer (7yw copies 7 words)
yy    copies a line into a buffer (3yy will copy 3 lines)

Once the desired text is yanked, place the cursor in the spot in which you wish to insert the text and then use the put command (p for line below or P for line above) to insert the contents of the buffer.

Replacing or Changing Characters, Words, and Lines

When you are using the following commands to replace text, you will be put temporarily into insert mode so that you can change a character, word, line, or paragraph of text.

r    replaces the current character with the next character you enter/type.
       Once you enter the character you are returned to command mode.
R    puts you in overtype mode until you hit ESC which will then return
       you to command mode.
cw    changes and replaces the current word with text that you type.  A dollar
       sign marks the end of the text you're changing.  Pressing ESC when you
       finish will return you to command mode.

Inserting a Blank Line

To insert a blank line below the line your cursor is currently located on, use the o key and then hit ESC to return to the command mode . Use O to insert a line above the line the cursor is located on.

Appending Text

You can use the append command to add text at any place in your file. Append (a) works very much like Insert (i) except that it insert text after the cursor rather than before it. Append is probably used most often for adding text to the end of a line. Simply place your cursor where you wish to append text and press a. Once you’ve finished appending, press ESC to go back to command mode.

Joining Lines

Since vi does not use automatic word wrap, it is not unusual in editing lines to end up with lines that are too short and that might be improved if joined together. To do this, place your cursor on the first line to be joined and type J. As with other commands, you can precede J with a number to join multiple lines (4J joins 4 lines).


Be sure to remember this command. When you make a mistake you can undo it. DO NOT move the cursor from the line where you made the change. Then try using one of the following two commands:

u    undoes the last change you made anywhere in the file.  Using u again
       will "undo the undo".
U    undoes all recent changes to the current line.  You can not have moved
    from the line to recover the original line.

Closing and Saving Files

When you edit a file in vi, you are actually editing a copy of the file rather than the original. The following sections describe methods you might use when closing a file, quitting vi, or both.

Quitting and Saving a File

The command ZZ (notice that it is in uppercase) will allow you to quit vi and save the edits made to a file. You will then return to a Unix prompt. Note that you can also use the following commands:

:w    to save your file but not quit vi (this is good to do periodically in
    case of machine crash!).
:q    to quit if you haven't made any edits.
:wq    to quit and save edits (basically the same as ZZ).

Quitting without Saving Edits

Sometimes, when you create a mess (when you first start using vi this is easy to do!) you may wish to erase all edits made to the file and either start over or quit. To do this, you can choose from the following two commands:

:e!    reads the original file back in so that you can start over.
:q!    wipes out all edits and allows you to exit from vi.

EX. NO. :


A Linux shell is a command language interpreter, the primary purpose of which is to translate the command lines typed at the terminal into system actions. The shell itself is a program, through which other programs are invoked

What is a shell script ?

How to work with shell?


In the dollar prompt type

$ vi < file name>

Where vi is the editor ,it will open a new window in which you can type the program you want


After typing the program press ESC and : together then at the bottom of the vi screen you can see i.e. prompt .In that type as wq which means write and quit i.e. the content what is typed will be written and saved into that file that has been created


Once wq is typed at the : prompt ,the prompt would change to $ symbol in which you have to do the following

$ sh < file name >

Sh – command is used to run the shell program

<file name> – is the name of the file for which the output is to be got

Basically to print a text in the your shell programs echo command is used

Identifying System Variables

  1. The shell is the primary agency that determines a user’s environment. Determine which shell that you are using by typing the following command:

echo $SHELL

Write the output

2.     PATH is one of the important system variables. It provides the shell with a searchable path to explore in order to find commands stored in various directories in the file system structure. Once the command entered on the command line is found, the shell can interpret the command. Determine your shell’s path settings.

echo $PATH

Write your output

3.     HOME stores the user’s home directory after a successful login. Each user’s home directory is named after their user account name. Determine your home directory settings.

echo $HOME

Write your output

4.     LOGNAME is the variable that holds your username.


Write your output

5.     MAIL provides UNIX with an absolute path to each user’s mailbox. Determine your MAIL settings.

echo $MAIL

Write your output

6.     MAILCHECK determines how often the shell checks for the arrival of new mail. MAILCHECK is set for 600 seconds by default and can be modified by the super user. Determine your MAILCHECK settings.


Write your output

7.     PS1 is the primary prompt string for the shell. Determine your PS1 settings

echo $PS1

Write your output

8.     PS2 is the secondary string for the shell. If the shell does not have enough information on the command line to interpret the command, it presents the user with the secondary prompt. The user can finish the command line on the secondary prompt line and then hit the enter key. Determine your PS2 settings

echo $PS2

Write your output

9.     CDPATH is the variable search path used by the cd command. CDPATH works the same as PATH except it locates directories and not shell commands. Determine your CDPATH setting.

echo $CDPATH

Write your output

  1. TERM is the variable that indicates the type of terminal you are using. Determine your TERM setting.

echo $TERM

Write your output



if [ condition]

then <action>



fi (end of if)


while <condition>





Case $<option> in

  1. <statements>;;
  2. <statements>;;
  3. ..




*) <error statement>;;


For loop

For(( intitialization;condition;incremetation/decrementation))



To write a shell script to find the area of the triangle


Step1 : get the base and height

Step2 : calculate the area

Step3 : Display the result



To write a shell script which accepts a number less than 50 and display its square


Step1 : Get the number

Step2 : Check if the number is less than 50. If the number is less than 50 then compute

the square of the number

Step3 : Display the result.



To write a shell script display a list of odd numbers below a given number


Step1 : Get the limit

Step2 : Initialize count to 1

Step3 : Display the list of odd numbers by incrementing count by 2 until the given limit.



To write a shell script to print the Fibonacci series


Step1 : get the limit

Step2 : add the first two numbers to produce the third number

Step3 : add the second and third number to get the fourth number and so on

Step4 : display the series



To write a shell script to read the marks of 5 subjects from user and calculate the average and grade


Step1 : Read the Marks

Step2 : calculate the average

Step3 : if the average is greater than 75 then assign grade as “Distinction”

if the average is between 60 to 75 then assign grade as “First Class”

if the average is between 50 to 59 then assign grade as “Second Class”

else then assign grade as “Fail”



To write a shell script to find whether a given character is vowel or constant


Step1 : Read the characters

Step2 : If it matches with any of the vowels a,e,i,o,u print it as vowel

Step3 : Otherwise print it as a constant



To write a shell script for a menu driven program.


Step1 : Get the option, use case statement to display the various functions

Step2 : first option to view the content of the home directory

Second option to list the users who have logged

Third option to print the present working directory

Fourth option to count the words, characters and lines of a file

Fifth option to print the type of file

Step3 : Display the result according to the option chose



To write a shell script to check whether the given string is a palindrome or not


Step1 : read an input string

Step2 : find the length of the string

Step3 : extract the input string into another variable starting from the last character

Step4 : check whether the input string and the reversed string are the same

Step5 : if so, display “given string is a palindrome” else display “given string is not

a palindrome”



To write a shell script to accept the name of the user and check out if the user has

Logged in or not.


Step1 : accept username from command line

Step2 : use ‘grep’ filter ,extract username from /dev/null file

Step3 : check whether the input username is in the /dev/null file

.If the username is present in
the file,display message as “user has logged in”

else, display the message as “user has not logged in”



To write a shell script to find the number of ordinary files and directory files in the current directory .


Step1 : Read the directory name

Step2 : Check if the number of command line arguments read .

Step3 : If the number of arguments read is less than one, then display the message as

“invalid message”

Step4 : Check whether the file is ordinary file or directory file[-f or –d]

Step5 : Using ‘grep’ filter, extract the number of files and directory files in two variables

Step6 : Display the count of files and directory files



To write a shell script to accept the filenames and display the file permission from the long listing of files


Step1 : Accept filenames from command line

Step2 : In a for loop, using the ‘cut’ command extract the file permission from the long

listing of files

Step3 : Display the filenames and their permission.



To write a shell script to convert the content of given files to uppercase letters


Step1 : Accept filenames to be converted from command line

Step2 : Using the ‘tr’ command to convert the content of file to upper case

Step3 : Display the content of converted files



To write a C program to perform file operations using file descriptor


Step 1: Get file name from user

Step 2: Get the string and find the length of the string

Step 3: Open the file in write mode

Step 4: Write the string in the file

Step 5: Close the file

Step 6: Open the file in read mode

Step 7: Read the contents of the file and store it in a temporary storage space

Step 8: Print the buffer contents on the screen

Step 9: Close the file.



To write a C program to create a new process using fork


Step1 : Create the process using fork() system call

Step2 : Check the process id of current process

If it is 0 then display as “child process” and also display the process id of current and parent process

Else it is a “parent process” and display the process id of current process and parent process



To write a C program to implement grep unix commands


Step1 : Use system function to implement grep unix commands

  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: