Operating System and Administration (CO2011)

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What is a major reason why UNIX became so popular?

It is written in a high-level language, making it easy to read, understand, change, and move to other machines.

What is a key characteristic of the user interface in UNIX?

It has a simple user interface that has the power to provide the services that users want.

How does the file system in UNIX facilitate maintenance and implementation?

It uses a hierarchical file system that allows easy maintenance and efficient implementation.

What is the format of files in UNIX that makes application programs easier to write?

A consistent format for files, the byte stream. Signup and view all the answers

How does UNIX provide interface to peripheral devices?

It provides a simple, consistent interface to peripheral devices. Signup and view all the answers

What is a key feature of UNIX that allows for the creation of complex programs?

It provides primitives that permit complex programs to be built from simpler programs. Signup and view all the answers

What is one of the key features of UNIX that allows users to write programs that run on different hardware implementations?

It hides the machine architecture from the user. Signup and view all the answers

What was the significance of the 1973 Fourth Edition of UNIX?

It was rewritten in C, making it portable and changing the history of OS's. Signup and view all the answers

What was the first version of UNIX to be widely available outside of Bell Labs?

The Sixth Edition, also known as Version 6. Signup and view all the answers

What notable features were introduced in the 1979 Seventh Edition of UNIX?

C, UUCP, and the Bourne shell. Signup and view all the answers

What was the significance of the 1982 release of System III?

It was the first public release outside Bell Laboratories. Signup and view all the answers

What was introduced by Microsoft in 1980?

Xenix. Signup and view all the answers

What happens to a program after a user compiles it in Unix?

The program resides on disk as an executable file. Signup and view all the answers

What does the term 'process' describe in the context of Unix?

A program that is actually running within the purview of Unix. Signup and view all the answers

What are the steps that Unix takes when a user requests to run a program?

Unix loads the program from the executable file on disk, builds appropriate data structures, and then starts it running. Signup and view all the answers

What is a process to Unix?

A (fairly complex) data structure in which Unix keeps all of the information about the status of the program that is running. Signup and view all the answers

What is the significance of the TRAP instruction in Unix system calls?

It does the actual call to the Unix system service in question. Signup and view all the answers

What are examples of functions that require accessing hardware and are therefore only available through services provided by the operating system?

printf, exit, and open. Signup and view all the answers

What is the outcome when the fork() system call is executed?

A new complete copy of the program main is created, including all its data and code areas as they exist at that moment. Signup and view all the answers

What value does the child process return from the fork() call?

Zero Signup and view all the answers

What happens to the parent process when it resumes running after the fork() call?

It returns from the call to fork() with a nonzero return value. Signup and view all the answers

What happens when a process such as P25 executes the wait system call?

It causes a Unix service to be accessed which puts the process to sleep by putting its data structure into a wait queue. Signup and view all the answers

What does the exec1 system call do in the child process?

Replaces the program and data areas of P50 with a new program (program copy). Signup and view all the answers

What is the purpose of I/O redirection in Unix?

To redirect output of a command into a file or to issue another command on the output of one command. Signup and view all the answers

How does the operating system determine which process to run, the child or the parent?

Either the child process or the parent process can run, putting the other on the ready to run queue. Signup and view all the answers

What are the two building block primitives of Unix?

I/O redirection and Pipe(|). Signup and view all the answers

What is the default input device for most Unix commands?

The keyboard, which is the standard input (stdin) device. Signup and view all the answers

What is the state of the child process when it starts running?

It starts by returning from the call to fork() with a return value of zero. Signup and view all the answers

What happens when a child process finishes executing?

Unix will wake up any process that was waiting for it to finish and put the data structure for that process on the ready to run queue. Signup and view all the answers