Question

Question 1

1. What Unix command can be used to change the access permission of a file ?   and how ?

2. Explain how pipe works in Unix. Give one example; Explain how redirect works in Unix and give an example.

3. Explain the structure of Unix file system and how absolute and relative paths work

4. What is UML ?   Briefly explain two types of diagrams in UML.

5. Briefly explain two types of testing methods for software development and the major stages in software development cycles

Answer 1

1

a.What Unix command can be used to change the access permission of a file ?   and how ?

"chmod" command is used to change the access permissions of file.It changes the permission according to the modes.There are to types of mode i.e numerical mode and symmetric mode.Mode describes what permissions will be changed.Modes are specifies with octal numbers or letters.

Syntax:

chmod[reference][operator][mode] file

a.Explain how pipe works in Unix. Give one example; Explain how redirect works in Unix and give an example.

Pipe is a form that allows one system to send one command or process to another command or process for further processing.It provides one way traffic or pipe flow of data.In Unix, pipe is created using pipe system call.There are two discriptors field[0] that is used for read and field[1] that is used for write.

When pipe is used in Unix,one process is used to write to stdout and other reads from stdin.Pipes uses"grep" and "sort" command.Grep command is used to find strings from text document and sort command is used to sort content of file in alphabaticall order.

a.Explain the structure of Unix file system and how absolute and relative paths work?

The Unix file system is a metho used for logically organizing and storing large quantities of data to manage system easily. In Unix file system file is the smallest storage unit. A file system consists of files, relationships to other files, and attributes of each file. File attributes are information relating to the file, but do not include the data contained within a file.

In Unix file system there is a multilever hierarachy.In which directory at top is known as root and represented as"/".This representation is known as directory tree.Other files are descendents or childs of root.

Path is a unique location of file in file system.Absolute path is specifying location from root.It starts from root and then goes down.We write / after every file name.Relative path is path related to present working file or directory.It never starts with "/".In this we use single dot and two dots for representing current directory and parent directory respectively.

a.What is UML ?   Briefly explain two types of diagrams in UML

UML is Unified Modeling Language that is used for modeling and documenting software.It is diagrammetic representation of software components.It is used as general purpose modelling language.Two types of diagram in UML are:

1.Structural

2.Behavioral

Structure diagrams show the things in the modeled system. They show different objects in a system.

Behavioral diagrams show what will happen in a system. They describe how the objects interact with each other to create a functioning system.

a.Briefly explain two types of testing methods for software development and the major stages in software development cycles

Two types of testing methods for software development are functional testing and non-functional testing.

Functional testing tests the functionality of system or we can say how system performs its functionality.

Non Functional testing tests how software responds in various conditions.

Major stages of software development cycles are:

1. Planning
2. Requirement analysis
3. Designing
4. Software development
5. Deployment
6. Testing
7. Maintainence

NOTE:

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