Unix Commands & vi Editor Lab - BITS Pilani | Exercises Computer Programming

BIRLA INSTTUTE OF TECHNOLOGY & SCIENCE, PILANI (RAJ.)

First Semester 2019-20

CS F111 Computer Programming

LAB SESSION #2

(Basic Unix Commands and vi Editor)

 Unix is a multi-user, multi-tasking operating system, and Linux is a variant of Unix that

we shall be using throughout this course.

 Everything is treated as a file in Unix. One or more files are stored inside a directory (i.e.,

folder).

 As soon as you are logged in, Unix places you in a directory that will be your “home”

directory. This will vary for each user. The home directory is also denoted by the symbol ~

(tilde, found below the <Esc> key on your keyboard).

Attempt each of the following tasks on the Linux machine, and write down the

corresponding Linux commands you used for each task in your notebook:

1. How do you make the system print out the name of your home directory?

You notice that a long string starting with the / character is printed, with words separated

by the / character again. The starting / is called the root directory under which all other

directories and sub-directories reside.

Your instructor will explain (or would have already explained) to you about absolute and

relative paths.

2. What is the parent directory of your home directory?

Just as the home directory is denoted by ~ symbol, the current directory is denoted by the

symbol ‘.’ (period), while the parent is denoted by ‘..’ (two periods).

3. Change to the parent directory using (i) absolute path addressing, and (ii) relative path.

4. Make a directory called dir1 under your home directory.

a. Change to this directory.

b. Make three empty files: file1 file2 and file3 under the current directory.

(You can either use the touch command, or the > operator. Try both options.)

c. Make a sub-directory called dir1-1 under the current directory.

5. Draw the file structure of the existent files and directories under your home directory.

6. Remove the subdirectory dir1-1.

7. Try now removing dir1. Why is this not happening? Ask your instructor how to remove

dir1.

Input and Output Redirection

Most Unix system commands take input from your keyboard and send the resulting output to

your terminal. A command normally reads its input from the standard input, which happens to

be your keyboard by default. Similarly, a command normally writes its output to standard output,

which is again your terminal by default. However, these default streams can be changed using

input/output redirection, for instance, an input taken from a file or the output that goes to a file.

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BIRLA INSTTUTE OF TECHNOLOGY & SCIENCE, PILANI (RAJ.)

First Semester 2019- CS F111 Computer Programming

LAB SESSION # (Basic Unix Commands and vi Editor)  Unix is a multi-user, multi-tasking operating system, and Linux is a variant of Unix that we shall be using throughout this course.  Everything is treated as a file in Unix. One or more files are stored inside a directory (i.e., folder).  As soon as you are logged in, Unix places you in a directory that will be your “home”

directory. This will vary for each user. The home directory is also denoted by the symbol ~

(tilde, found below the key on your keyboard).

Attempt each of the following tasks on the Linux machine, and write down the corresponding Linux commands you used for each task in your notebook:

How do you make the system print out the name of your home directory? You notice that a long string starting with the / character is printed, with words separated by the / character again. The starting / is called the root directory under which all other directories and sub-directories reside. Your instructor will explain (or would have already explained) to you about absolute and relative paths.
What is the parent directory of your home directory? Just as the home directory is denoted by ~ symbol, the current directory is denoted by the symbol ‘.’ (period), while the parent is denoted by ‘..’ (two periods).
Change to the parent directory using (i) absolute path addressing, and (ii) relative path.
Make a directory called dir1 under your home directory. a. Change to this directory. b. Make three empty files: file1 file2 and file3 under the current directory. (You can either use the touch command, or the > operator. Try both options.) c. Make a sub-directory called dir1-1 under the current directory.
Draw the file structure of the existent files and directories under your home directory.
Remove the subdirectory dir1-.
Try now removing dir1. Why is this not happening? Ask your instructor how to remove dir.

Input and Output Redirection

Most Unix system commands take input from your keyboard and send the resulting output to your terminal. A command normally reads its input from the standard input, which happens to be your keyboard by default. Similarly, a command normally writes its output to standard output, which is again your terminal by default. However, these default streams can be changed using input/output redirection, for instance, an input taken from a file or the output that goes to a file.

The output from a command normally intended for standard output can be easily diverted to a

file instead. This capability is known as output redirection. If the notation > f1 is appended to

any command that normally writes its output to standard output, the output of that command will be written to file f1 instead of your terminal. This is output redirection. Just as the output of a command can be redirected to a file, so can the input of a command be redirected from a file.

As the greater-than character > is used for output redirection, the less-than character < is used

to redirect the input of a command. This is input redirection.

Store the list of all the files and directories (long listing) in a file called dirfile. (You may not understand the significance of the output, but you will soon learn in the lecture.)
Display the contents of dirfile on the screen using the cat command.
Store in a file called userlist , the list of users who are currently logged into the system.
Combine the contents of dirfile and userlist and store in a file called file.
Print the number of lines, words and characters in file1 using the wc command.
Copy the contents of file1 into file.
Append the following two lines into file2 : This is file2. And I am using Linux!

Beginning to use the vi editor

Open file3 using vi editor and add the following line of text to it: This is file3!
Save and exit editing file3. You will now be at the shell prompt.
Append the contents of file2 to file.
Open file3 using vi editor again, and insert the following line after the first line: ( asterisks)
Now insert a line of 25 asterisks after the last line of file3 , just by using few vi commands (that is, do not type out the line again).
Save the modified file into another file named file4 , without exiting vi editor.
Now, count the number of characters in file4, without exiting vi editor. (You can escape to the shell by typing ‘!’ in the command line mode.)
Exit vi editor, so that none of these changes you made is recorded in file3.

Unix Commands & vi Editor Lab - BITS Pilani, Exercises of Computer Programming

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Partial preview of the text

Download Unix Commands & vi Editor Lab - BITS Pilani and more Exercises Computer Programming in PDF only on Docsity!

BIRLA INSTTUTE OF TECHNOLOGY & SCIENCE, PILANI (RAJ.)

directory. This will vary for each user. The home directory is also denoted by the symbol ~

file instead. This capability is known as output redirection. If the notation > f1 is appended to

As the greater-than character > is used for output redirection, the less-than character < is used