Unix Operating System Overview

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Questions and Answers

What indicates an absolute pathname?

A pathname beginning with a tilde (~)

A pathname beginning with / (correct)

A pathname that does not start with /

A pathname with special characters

What does the command 'alph% cd ..' do?

Changes the directory to the current directory

Moves one level up in the directory structure (correct)

Creates a new directory

Displays the contents of the current directory

Which command sets the environment variable PRINTER to lpg17?

setenv PRINTER lpg17 (correct)

export PRINTER=lpg17

lpr setenv PRINTER lpg17

lpr -Plpg17 file.ps

What does the single full stop (.) represent in pathnames?

The current directory Signup and view all the answers

How can you print a file to a different printer using the lpr command after changing the PRINTER variable?

By entering 'lpr file.ps' after modifying PRINTER Signup and view all the answers

Which command can be used to view the current working directory?

pwd Signup and view all the answers

What does the command 'alph% mv ../ques.1 fortran' do?

Moves ques.1 from the current directory into the fortran directory Signup and view all the answers

Which symbol is used to reference an environment variable?

$ Signup and view all the answers

What is the primary function of special files in Unix?

To represent physical devices for system interaction. Signup and view all the answers

How is the root directory represented in the Unix file system?

As a forward slash (/) Signup and view all the answers

Which of the following statements about file names in Unix is correct?

File names can be of any length unlike in MS-DOS. Signup and view all the answers

What is the significance of a user's home directory in Unix?

It is the default directory users are placed in upon login. Signup and view all the answers

In which order must the components of a Unix command be typed?

Command, options, arguments Signup and view all the answers

How can options be combined in typical Unix command usage?

Options can be combined as long as they are prefixed with a single dash (-). Signup and view all the answers

What is the purpose of the 'man' command in Unix?

To access the online manual pages for commands. Signup and view all the answers

What indicates that a command and its options are correctly formatted in Unix?

Maintaining consistent spacing between command and options. Signup and view all the answers

What is the main purpose of the 'pwd' command in UNIX?

To print the working directory Signup and view all the answers

Which command would you use to create a new directory in UNIX?

mkdir Signup and view all the answers

What does the command 'rm' do in UNIX?

Removes files and directories Signup and view all the answers

What functionality does the 'grep' command provide?

Searches for strings in files Signup and view all the answers

When using the 'mv' command, which of the following can occur?

Files can be both moved and renamed Signup and view all the answers

What is the use of the 'chmod' command in UNIX?

To change access permissions Signup and view all the answers

Which command would you use to see the contents of a file one screen at a time?

more Signup and view all the answers

What is the function of the 'diff' command in UNIX?

To compare two files and indicate differences Signup and view all the answers

What does the '&' character do when used in a command line?

It sends a command to the background. Signup and view all the answers

What is the purpose of the 'jobs' command?

To list current jobs running in the shell. Signup and view all the answers

What does the output 'prime Done' indicate?

The prime program has finished executing. Signup and view all the answers

Which command is used to bring a job back to the foreground?

fg Signup and view all the answers

What is the main purpose of using the > operator in shell commands?

To redirect standard output to a file Signup and view all the answers

What happens when you type 'xclock' without the '&' at the end?

It runs in the foreground and blocks the prompt. Signup and view all the answers

Which command will produce output similar to that of the command 'date' when using an input file named 'todays.date'?

addup < todays.date Signup and view all the answers

What does typing 'ps' do in relation to job control?

It shows the active processes and their process numbers. Signup and view all the answers

How can you suspend a running job in the shell?

By typing Ctrl + Z. Signup and view all the answers

What is the expected effect of executing 'cat todays.date' after 'date > todays.date'?

It will display the contents of todays.date on the monitor Signup and view all the answers

Which command is used to kill a process from the window menu?

kill Signup and view all the answers

When using a pipe as shown in 'ls -l /usr/bin | more', what is the role of the command 'more'?

To display output one page at a time Signup and view all the answers

What does the < operator do in shell commands?

It sends standard input from a file to a command Signup and view all the answers

What will happen if 'addup < todays.date > answer' is executed, given the contents of todays.date is valid for addition?

The result will be saved in the file 'answer' Signup and view all the answers

In the context of shell commands, which of the following statements is true regarding stderr?

Stderr displays error messages in the monitor Signup and view all the answers

Which of the following reflects the correct way to use a file with the stdin operator?

cat input.deck | addup Signup and view all the answers

Study Notes

Intro

Unix is a multi-user, multi-tasking operating system, it allows for multiple users to access the computer at the same time, and run multiple programs concurrently.
The Unix file system is hierarchical, meaning that every file resides within a directory, a directory can contain files, subdirectories, or both
Unix has three types of files: Normal files (can contain data, text, code, executables etc), Special files (represent physical devices like terminals and disk drives), and Directories (contain pointers to other files and directories).
File names in UNIX can be as long as needed
The root directory is denoted by "/" and is the parent directory of all other directories
Users each have a "home" directory, the directory they are located in when they log in, they can access other parts of the system by navigating the file system.

Commands

Most Unix commands follow the format command [options...] [arguments...] spaces or tabs separate components
Commands must be typed in the correct case

Man Command

The man command is used to access the manual pages for Unix commands.
Provides detailed information about how to use specific commands and their options

pwd Command

The pwd command stands for "print working directory"
It displays the current directory the user is in

cd Command

The cd command stands for "change directory"
It allows the user to move between directories in the file system

ls Command

The ls command stands for "list"
It lists the contents of a directory, files and subdirectories

mkdir Command

The mkdir command stands for "make directory"
It creates a new directory in the file system

rmdir Command

The rmdir command stands for "remove directory"
It removes an empty directory from the file system

cp Command

The cp command stands for "copy"
It copies files or directories from one location to another, with the option to create a new directory if needed.

cat Command

The cat command stands for "concatenate"
It displays the contents of a file on the screen

more Command

The more command displays the contents of a file one screen at a time allowing the user to scroll through the file's content.

mv Command

The mv command stands for "move"
It moves files or directories from one location to another, also renames files or directories.

rm Command

The rm command stands for "remove"
It deletes files or directories from the file system

chmod Command

The chmod command stands for "change mode"
It allows the user to change the permissions of files and directories, which controls who can access them.
Permission modes typically include: read, write, and execute

diff Command

The diff command is used to compare two files and find the differences between them

grep Command

The grep command stands for "global regular expression print"
It searches lines within files for specific patterns, useful for searching for strings within files

wc Command

The wc command stands for "word count"
It counts the number of words, lines, and characters in a file

Starting Remote Clients

Clients can connect to remote machines over a network

Shells

Shells are interactive programs that provide an interface for interacting with the Unix kernel
They allow users to run commands and access the operating system

Files and Pathnames

Files are organized within a hierarchical directory structure
Pathnames are used to identify specific files and directories within the system

Variables and Environments

Variables and environment variables help to store information and preferences for user access
Variables can be set and changed to customize behavior of both user and shell

Wildcards

Wildcards are special characters that can be used in file names
Examples include: * (match any string of characters), ? (match any single character), [ ] (match a range of characters or a set of characters).

Filename Expansion

The shell expands wildcard characters to create a list of matching files.

Redirection and Pipes

Redirection is a method to send data between programs, it can be used to redirect input and output.
Pipes connect the output of one program to the input of another

Job Control

Job control allows users to manage background processes
The & symbol sends a command to the background, allowing other tasks to run in the foreground

Configuring Your Working Environment

Users can customize their working environment through configuration files

Mtools

Mtools are a set of commands for working with floppy disks

Xman

Xman is a graphical interface for viewing Unix manual pages.

Xcalc

Xcalc is a graphical calculator for use with the X Window System.

Finger

The finger command is used to find information about users on a remote computer.

Compression Utilities

Compression utilities are used to reduce the size of files.
Examples include: gzip, bzip2, zip

Printing and Scanning

Unix systems can interface with printers and scanners

Remote Logging In

Remote users can connect to Unix systems over network connections

File Transfer

Unix systems support file transfer protocols like FTP and SCP for moving files between machines

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Description

This quiz covers the fundamentals of the Unix operating system, including its multi-user capabilities, hierarchical file system, and types of files. It also delves into the structure of commands and their components used in Unix. Test your knowledge on Unix functionalities and file management.