OPS Midterms

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Questions and Answers

What is one of the strengths of Command Line Interfaces (CLIs)?

Well-suited for automation, such as mass-conversion of thousands of images (correct)

Well-suited for editing images and documents

Well-suited for occasional tasks

Requires far more data than Graphical User Interfaces (GUIs)

GUIs are well-suited for automation tasks.

False

What type of interface was dominant on personal computers before Microsoft Windows and the Apple Macintosh existed?

Text User Interfaces

A typical CLI display contains about ______ kilobytes of data.

2 Signup and view all the answers

Why are CLIs often used over remote connections?

Because they require far less data than GUIs Signup and view all the answers

Graphical User Interfaces (GUIs) are well-suited for occasional tasks.

False Signup and view all the answers

Match the following interfaces with their characteristics:

Command Line Interfaces (CLIs) = Well-suited for automation tasks Graphical User Interfaces (GUIs) = Well-suited for graphical tasks Text User Interfaces (TUIs) = Dominant on personal computers before GUIs Signup and view all the answers

What was the state of computing in the very early days?

Impossible to standardize Signup and view all the answers

What type of user interface enables the user to interact with multiple application windows?

Graphical User Interface (GUI) Signup and view all the answers

Operating systems provide at least three types of user interfaces.

False Signup and view all the answers

What is the primary purpose of the user interface?

to enable the user to interact with the system Signup and view all the answers

Most operating systems provide a set of basic starter applications, such as a _______________, clock, a few games, and sometimes a web browser.

text editor Signup and view all the answers

Match the following user interfaces with their descriptions:

CLI = enables the user to enter commands and view output GUI = enables the user to interact with multiple application windows TUI = full-screen text interfaces such as file editors and file managers Signup and view all the answers

Utilities in an operating system can use either the GUI or CLI.

True Signup and view all the answers

What is another term for Text-Based User Interface?

Text User Interface (TUI) Signup and view all the answers

What type of tasks do utilities in an operating system perform?

setup, configuration, and maintenance Signup and view all the answers

What is the primary function of the kernel?

To manage resources and security settings Signup and view all the answers

System libraries are provided by third-party vendors.

False Signup and view all the answers

What are system libraries?

A common set of software routines that programs access to perform common operations. Signup and view all the answers

The kernel operates in a special ______________________ mode, which enables it to manage resources and security settings.

Privileged Signup and view all the answers

Match the following components of an Operating System:

Kernel = Manages resources and security settings System Libraries = Provides common software routines Services = Runs continuously in the background User Interface = Provides interaction with the user Signup and view all the answers

The kernel is loaded by the computer's firmware.

True Signup and view all the answers

What are services in an Operating System?

Programs that run continuously in the background, providing services such as WiFi authentication, print management, and file sharing. Signup and view all the answers

What is NOT a component of an Operating System?

Compiler Signup and view all the answers

What was a key difference between Unix and DOS?

DOS did not have a hierarchical filesystem while Unix did Signup and view all the answers

DOS used the forward-slash character in filenames.

False Signup and view all the answers

What was the version of DOS that introduced Unix-like features?

2.0 Signup and view all the answers

Microsoft introduced features from ______________ into DOS.

Xenix Signup and view all the answers

What was the reason DOS used the backward-slash character in filenames?

Because it was already being used for another purpose Signup and view all the answers

DOS was a multi-tasking system.

False Signup and view all the answers

Match the following operating systems with their characteristics:

DOS = Single-tasking system Unix = Multi-tasking system with hierarchical filesystem CP/M = Single-tasking system with flat filesystem Signup and view all the answers

What was the original heritage of DOS?

CP/M-like Signup and view all the answers

What is the primary purpose of hardware abstraction in an Operating System?

To hide hardware details from application software Signup and view all the answers

One customer of a cloud server can access another customer's data.

False Signup and view all the answers

What is the primary benefit of maintaining the programming model in an Operating System?

It allows programmers to create software using a single conceptual framework Signup and view all the answers

An application can send data to the network in the same way regardless of whether the connection uses _______________, WiFi, or 5G.

wired ethernet Signup and view all the answers

Match the following benefits of Operating System abstraction with their descriptions:

Hardware Abstraction = Hides hardware details from application software Programming Model = Provides a single conceptual framework for programmers Multi-Tenancy = Allows multiple customers to access a single resource Signup and view all the answers

What is an example of an Operating System abstraction?

A program requesting input from the keyboard Signup and view all the answers

Multiple programs can be written to work in the same region of memory without conflict.

True Signup and view all the answers

What is the primary benefit of multi-tenancy in a cloud server?

It allows multiple customers to access a single resource, while keeping their data isolated from each other Signup and view all the answers

What is the current significance of the Unix trademark?

Not as significant as it once was Signup and view all the answers

Linux is an officially recognized Unix system.

False Signup and view all the answers

What are the two operating systems focused on in this course?

Windows (version 10) and Linux Signup and view all the answers

A CLI is provided by two components: a terminal program which accepts user input from a _______________ and displays text output.

keyboard Signup and view all the answers

Match the following operating systems with their characteristics:

Mac OS and iOS = Unix-like Linux = Unix-like FreeBSD and OpenBSD and NetBSD = Unix-like Windows = Proprietary Signup and view all the answers

What is the primary interface available on the lab computers?

Both GUI and CLI Signup and view all the answers

Graphical User Interfaces (GUIs) are well-suited for automation tasks.

False Signup and view all the answers

What is the name of the large server system that provides a Linux CLI by remote connection?

Matrix Signup and view all the answers

What was added to PC-DOS/MS-DOS 2.0?

Hierarchical filesystems Signup and view all the answers

All modern versions of Windows are derived from MS-DOS.

False Signup and view all the answers

When was the X Window System introduced?

1984 Signup and view all the answers

Unix was originally a proprietary product of ________________.

Bell Labs / AT&T Signup and view all the answers

Match the following operating systems with their characteristics:

Unix = Original proprietary product of Bell Labs / AT&T MS-DOS = Added hierarchical filesystems in version 2.0 Windows NT = Combined features from DOS/Windows and OS/2 OS/2 = Jointly-developed by Microsoft-IBM Signup and view all the answers

What was the primary purpose of the X Window System?

To add GUIs to Unix systems Signup and view all the answers

Unix became a family of related operating systems customized by various vendors.

True Signup and view all the answers

What was the new 32-bit operating system released in 1993?

Windows NT 3.1 Signup and view all the answers

What is the primary purpose of the kernel?

To manage resources and security settings Signup and view all the answers

System libraries are provided by third-party vendors.

False Signup and view all the answers

What are the two broad categories of software licenses in use?

Proprietary licenses and Open Source Licenses Signup and view all the answers

What type of argument is 'ls -l' in the command 'ls -l'?

Option Signup and view all the answers

The copyright holder can license the software to another party under a _______________________ license.

Open Source Signup and view all the answers

Open Source Software is generally protected by patent.

False Signup and view all the answers

What type of user interface enables the user to interact with multiple application windows?

Graphical User Interface (GUI) Signup and view all the answers

What is the primary purpose of the option '-l' in the command 'ls -l'?

To select 'long' output Signup and view all the answers

Match the following types of Open Source Licenses with their characteristics:

Free Software Licenses = require anyone redistributing the software to do so under the same terms as the software was received. Permissive Licenses = allow the open source software to be redistributed without the same permissions as the software was received under. Signup and view all the answers

The 'dir' command is used to list files in _______________ systems.

Windows Signup and view all the answers

Match the following types of arguments with their descriptions:

Option = Alters the operation of the command Option with a Value = Consists of an option immediately followed by a value Positional Argument = All other arguments, and their position may be significant Signup and view all the answers

DOS used the forward-slash character in filenames.

False Signup and view all the answers

What are the two operating systems focused on in this course?

Unix-like systems and other Operating Systems Signup and view all the answers

The 'cp' command is used to copy files in Windows systems.

False Signup and view all the answers

What is the purpose of the option '-h' in the command 'ls -l -h'?

To show human-readable sizes Signup and view all the answers

What type of argument is 'new' in the command 'cp old new'?

Positional Argument Signup and view all the answers

What is a shell?

A program that interprets commands and displays their output Signup and view all the answers

All commands are built into the shell.

False Signup and view all the answers

What is the name of the shell widely used on Linux systems?

Bash Signup and view all the answers

Commands may also be called ______________, utilities, applications, or executables.

programs Signup and view all the answers

Match the following shells with their primary usage:

Bash = Linux systems PowerShell = Windows systems CMD = Windows systems Signup and view all the answers

What is the primary purpose of a command?

To perform a specific task or function Signup and view all the answers

The terms 'programs', 'utilities', 'applications', and 'executables' are interchangeable only in the context of shell scripting.

False Signup and view all the answers

What is the structure of most commands?

command_name arguments Signup and view all the answers

What is the name of the course being discussed in the lecture?

OPS102 Signup and view all the answers

Labs account for 30% of the total mark in OPS102.

False Signup and view all the answers

What is the name of the Linux distribution that provides a command-line interface by remote connection?

Matrix Signup and view all the answers

The course OPS102 focuses on two operating systems: _______ and Windows.

Linux Signup and view all the answers

Why did the instructor swap weeks 1 and 2 in OPS102?

Because week 2 topics will help students in their other courses. Signup and view all the answers

All modern versions of Windows are derived from MS-DOS.

True Signup and view all the answers

Match the following course components with their weightage:

Labs = 20% Quizzes = 25% Mid-Term Test = 25% Final Test = 30% Signup and view all the answers

What is the course code that was replaced by OPS102 for SDDS students?

ULI101 Signup and view all the answers

What is required to access Matrix?

Being on-campus or connected to SenecaNet or VPN Signup and view all the answers

You can connect to Matrix from any location using SSH.

False Signup and view all the answers

What protocol is used to securely connect to Matrix?

SSH (Secure Shell) Signup and view all the answers

You can connect to Matrix from any Seneca lab workstation, or from your personal computer using ___________________.

SSH (Secure Shell) Signup and view all the answers

Why is SSH used to connect to Matrix?

For security reasons Signup and view all the answers

Web access is allowed to Matrix from off-campus.

True Signup and view all the answers

Match the following access methods with their descriptions:

On-campus = Physically present at Seneca campus Off-campus with VPN = Connected to Seneca VPN from outside Off-campus without VPN = No access to Matrix Signup and view all the answers

What is the name of the server system that provides a Linux CLI by remote connection?

Matrix Signup and view all the answers

What might be the reason you can't connect to matrix.senecapolytechnic.ca?

All of the above Signup and view all the answers

PuTTY is a terminal emulator for MacOS only.

False Signup and view all the answers

What is the port number used when connecting to matrix.senecapolytechnic.ca using PuTTY?

22 Signup and view all the answers

To connect to matrix from MacOS, you would use the command `ssh [email protected]`

senecausername Signup and view all the answers

What is the default connection type used in PuTTY?

SSH Signup and view all the answers

You should not log out of matrix.senecapolytechnic.ca when you're finished.

False Signup and view all the answers

Match the following platforms with their corresponding terminal emulators:

Windows = PuTTY MacOS = Terminal Linux = Terminal Signup and view all the answers

What is the hostname used when connecting to the Linux server?

matrix.senecapolytechnic.ca Signup and view all the answers

What is the name of the server cluster that provides a Linux CLI by remote connection?

Matrix Signup and view all the answers

All modern versions of Windows are derived from MS-DOS.

True Signup and view all the answers

What type of OS is CentOS?

a version of Linux Signup and view all the answers

Matrix has been configured to allow users to only interact with the Linux OS using a _______________ interface.

command line Signup and view all the answers

Match the following storage systems with their descriptions:

NFS = a file system that allows access to files on a remote computer HyperV = a virtual machine Signup and view all the answers

Linux is a multi-tasking system.

True Signup and view all the answers

What is the primary benefit of maintaining the programming model in an Operating System?

it allows multiple programs to work in the same region of memory without conflict Signup and view all the answers

How do Seneca students access the Linux OS on matrix?

using SSH Signup and view all the answers

What is the purpose of the /dev directory in a Linux file system?

To store device driver files Signup and view all the answers

A relative pathname always starts with a slash.

False Signup and view all the answers

What is the symbol used to represent the user's home directory in Linux?

tilde (~) Signup and view all the answers

In Linux, the path separator is a _______________.

forward slash (/) Signup and view all the answers

Match the following directory paths with their descriptions:

/home/cory = User's home directory /var = Dynamic files /tmp = Temporary files for programs /opt = Additional installed application programs Signup and view all the answers

The kernel operates in a user mode.

False Signup and view all the answers

What is the purpose of the /tmp directory in a Linux file system?

Temporary files for programs Signup and view all the answers

A full pathname that starts from the root of the hierarchy is called a _______________ pathname.

absolute Signup and view all the answers

What is the command to create a directory in Linux?

mkdir Signup and view all the answers

The 'rmdir' command can remove non-empty directories.

False Signup and view all the answers

What is the purpose of the 'touch' command?

Create an empty file or update the time of an existing file Signup and view all the answers

The 'rm' command is used to _______ files or directories.

remove Signup and view all the answers

Match the following commands with their functions:

mkdir = Create a directory mv = Move or rename files/directories cp = Create a copy of files/directories rm = Remove files or directories Signup and view all the answers

What is the command to move or rename files/directories in Linux?

mv Signup and view all the answers

The 'pushd' and 'popd' commands are used to change directories.

True Signup and view all the answers

What is the purpose of the 'cp' command?

Create a copy of files or directories Signup and view all the answers

What is a primary purpose of the "man" command in Linux/Unix systems?

To provide access to documentation Signup and view all the answers

In Linux/Unix, text files are commonly used for data, presentations, configuration, logs, and more.

True Signup and view all the answers

What is the primary function of file management skills in Linux/Unix systems?

To create files and directories, read the contents of files, copy files for backup purposes, move or rename incorrectly spelled filenames, and view text file contents without the danger of editing or corrupting those files. Signup and view all the answers

In Linux/Unix, the system and shell provide "easy" ways to deal with ______.

files Signup and view all the answers

What is a common use of file management skills in Linux/Unix systems?

All of the above Signup and view all the answers

Match the following file operations with their descriptions:

Creating files = To create new files Moving files = To rename or relocate files Copying files = To create duplicate files Deleting files = To remove files Signup and view all the answers

The "man" command is divided into sections, and you can see these sections by running "man man".

True Signup and view all the answers

What is the primary purpose of the "dir /?" command in Windows?

To provide help on the "dir" command. Signup and view all the answers

What is the purpose of file globbing in Linux?

To expand wildcards into a list of matching files Signup and view all the answers

File globbing is a feature provided by the kernel.

False Signup and view all the answers

What happens when you press the enter key after typing a command with wildcards?

The shell expands the wildcards into a list of matching files before executing the command. Signup and view all the answers

When you type a command with wildcards and press the enter key, the shell performs _______________________ on any wildcards on the command line before executing the command.

file name expansion Signup and view all the answers

Which of the following commands is used to find specific lines in a file?

grep Signup and view all the answers

The `find` command is used to sort the lines of a file.

False Signup and view all the answers

Match the following file operations with their descriptions:

sort = Sort the lines of a file uniq = Display identical consecutive lines only once cut = Remove undesired columns from your data in a file grep = Find specific lines in a file Signup and view all the answers

Bash shell automatically expands wildcards into the names of all the files and directories in the current working directory before executing the command.

True Signup and view all the answers

What is the purpose of the "touch" command in Linux/Unix systems?

To create an empty file or change the file's timestamp Signup and view all the answers

In Linux/Unix systems, the "cp" command can only copy files to a new directory.

False Signup and view all the answers

What is the purpose of the "rm" command with the "-r" option?

To remove directories recursively Signup and view all the answers

The "cat" command is used to ______ the contents of a file.

display Signup and view all the answers

Match the following Linux/Unix commands with their functions:

cp = Copy a file mv = Rename a file rm = Remove a file touch = Create an empty file or change the file's timestamp Signup and view all the answers

What is the purpose of the "head" command in Linux/Unix systems?

To display the beginning of a file Signup and view all the answers

In Windows, you can use the "cat" command to display the contents of a file without any additional software.

False Signup and view all the answers

What is the difference between the "mv" and "cp" commands in Linux/Unix systems?

The "mv" command renames a file, while the "cp" command copies a file. Signup and view all the answers

What is the purpose of the question mark (?) in globbing?

To match any exactly one character Signup and view all the answers

The character class [0-2] will match any character that is not 0, 1, or 2.

False Signup and view all the answers

What is the effect of using an exclamation mark (!) as the first character in a character class in globbing?

It inverts the class, making it match any character that is not listed in the class Signup and view all the answers

The command `rm img?.jpg` will delete all files with names starting with "img", followed by _______________, and ending with ".jpg".

any one character Signup and view all the answers

What is the interpretation of the pattern `ls File?.pdf`?

Lists all files with names starting with "File", followed by any exactly one character, and ending with ".pdf". Signup and view all the answers

Match the following patterns with their interpretations:

ls File?.pdf = Lists all files with names starting with "File", followed by any exactly one character, and ending with ".pdf". rm img?.jpg = Delete all files with names starting with "img", followed by any one character, and ending with ".jpg". ls File[0-2].pdf = Lists all files with names starting with "File", followed by either 0, 1, or 2, and ending with ".pdf". Signup and view all the answers

The command `ls File[0-2].pdf` will list all files with names starting with "File", followed by any zero or more characters, and ending with ".pdf".

False Signup and view all the answers

What is the purpose of globbing in the bash shell?

Globbing is used to expand filenames and directories based on wildcard characters and patterns Signup and view all the answers

What is the main purpose of a text editor?

To create, modify and save editing changes of text files Signup and view all the answers

Graphical User Interfaces (GUIs) are well-suited for automation tasks.

False Signup and view all the answers

What is the end-of-line indicator in UNIX/Linux?

new line (line feed or ^J or ) Signup and view all the answers

In Windows, the end-of-line indicator is a _______________ followed by a line feed.

carriage return (^M or ) Signup and view all the answers

Match the following text files with their uses:

System configuration files = Editing text files is an everyday activity for both programmers as well as administrators Scripts and programs = Edit System configuration files Documentation = Write/edit documentation Web pages = Develop web pages Signup and view all the answers

Why are text files important in Linux/Unix?

For data, presentations, configuration, logs, and more Signup and view all the answers

CLIs are well-suited for automation tasks.

True Signup and view all the answers

What is the name of the commands that can help when transferring text files between systems?

dos2unix(1) and unix2dos(1) Signup and view all the answers

Manual typewriters and teletype machines worked similar to how _______________ files work.

text files Signup and view all the answers

Match the following with their descriptions:

Text editors = Allows users to create, modify and save editing changes of text files Unix/Linux = System and shell provide “easy” ways to deal with files Line endings = End-of-line indicators in text files Signup and view all the answers

What was the original editor used on Unix systems?

ed Signup and view all the answers

Which of the following text editors is the default on many Linux distributions?

Nano Signup and view all the answers

The vi editor was developed by Bill Joy at UCBerkeley.

True Signup and view all the answers

The notation ^G in nano editor means pressing and holding the __________ key and then the G key.

control Signup and view all the answers

Which of the following text editors is known for its visual mode?

vi Signup and view all the answers

What is the purpose of the grep command?

to echo the ed syntax of: g/regexp/p Signup and view all the answers

Match the following text editors with their characteristics:

Nano = Easy to use and default on many Linux distributions VIM = Highly customizable and powerful Gedit = A popular text editor on Linux systems Notepad = A basic text editor on Windows systems Signup and view all the answers

All modern versions of Windows are derived from MS-DOS.

False Signup and view all the answers

The ed editor was replaced by __________ on Unix systems.

ex Signup and view all the answers

What is a benefit of using the nano editor?

It provides a menu at the bottom of the screen. Signup and view all the answers

The vim editor is an older version of the vi editor.

False Signup and view all the answers

What is the purpose of the ^G command in nano?

To get help at any time Signup and view all the answers

The _______ command is used to open a file in nano.

^R Signup and view all the answers

Why is it recommended to become familiar with vi/vim?

For anything beyond the absolute basics. Signup and view all the answers

Nano is a more advanced text editor than vi/vim.

False Signup and view all the answers

Match the nano command with its function:

^O = Save a file ^W = Find ^R = Open a file Signup and view all the answers

What is the purpose of the vimtutor(1) command?

To get started with learning vi/vim Signup and view all the answers

The nano editor is suitable for ________________ use.

casual, occasional Signup and view all the answers

Vi/vim is only used by programmers.

False Signup and view all the answers

What is the purpose of the "chmod" command in Linux?

To change permissions of a file Signup and view all the answers

In the "ls -l" output, the first character represents the file type.

True Signup and view all the answers

What are the three types of permissions that can be set for a file in Linux?

read, write, and execute Signup and view all the answers

The "chmod" command uses ______ methods to set permissions: symbolic and octal.

two Signup and view all the answers

Match the following permissions with their corresponding abbreviations:

Read = r Write = w Execute = x User = u Group = g Others = o Signup and view all the answers

What is the purpose of the "chmod" command with the "g+rw" option?

To add read and write permissions for the group Signup and view all the answers

In the octal method of setting permissions, permissions can be set explicitly by "chmod" with an octal number.

True Signup and view all the answers

What is the purpose of the "chmod" command with the "a-w" option?

To remove write permissions for all users Signup and view all the answers

What is the primary purpose of setting permissions in a multi-user operating system?

To control who has access to files and folders Signup and view all the answers

In Linux, directory permissions have the same meaning as file permissions.

False Signup and view all the answers

What are the three permission indicators in Linux?

Read, Write, and Execute Signup and view all the answers

In Linux, the ______________ permission allows the execution of a file as a command.

Execute Signup and view all the answers

What is the purpose of Access Control Lists (ACLs) in Linux?

To provide an advanced permission mechanism Signup and view all the answers

Match the following permissions with their descriptions:

Read = Read access to the file's contents Write = Permission to modify the file's contents Execute = Allows the execution of a file as a command Signup and view all the answers

In Linux, the kernel operates in user mode.

False Signup and view all the answers

Why is it necessary to have read permission to execute a script in Linux?

Because scripts need to be read before they can be executed Signup and view all the answers

What is the purpose of the setuid bit in a file's mode?

To run the file with the owner's permissions Signup and view all the answers

The `chmod` command with 3 octal digits sets the permissions for user, group, and others.

True Signup and view all the answers

What is the octal representation of the permissions `rwxr-x---`?

750 Signup and view all the answers

The `chmod` command with the octal number `754` sets the permissions to ______________.

rwx r-x r-- Signup and view all the answers

Match the following special permission bits with their descriptions:

a) setuid = 2. Runs the file with the owner's permissions. b) setgid = 3. Runs the file with the group's permissions. c) sticky bit = 1. Ensures that only the owner of a file or the root user can delete or modify it. Signup and view all the answers

What is the purpose of the sticky bit in a file's mode?

To ensure that only the owner of a file or the root user can delete or modify it Signup and view all the answers

What is the binary representation of the octal number `7` in permissions?

111 Signup and view all the answers

The command `chmod 755 file1.txt` sets the permissions to ______________.

rwxr-xr-x Signup and view all the answers

What is the purpose of the setuid bit in Linux?

To allow normal users to execute a command with root privileges Signup and view all the answers

The sticky bit is used to ensure the privacy and security of files in shared directories.

True Signup and view all the answers

What is the purpose of the umask in Linux?

to 'mask off' (disable) permission bits for files or directories created by a process Signup and view all the answers

The 'passwd' command allows users to change their own password without requiring ________________ access.

sudo Signup and view all the answers

What is the effect of the sticky bit on a directory?

Only the owner of a file can delete or rename it Signup and view all the answers

The umask is set on a per-user basis.

False Signup and view all the answers

Match the following Linux security features with their descriptions:

setuid = Allows normal users to execute a command with root privileges sticky bit = Ensures the privacy and security of files in shared directories umask = Masks off permission bits for files or directories created by a process Signup and view all the answers

What is the purpose of the 'passwd' command in Linux?

to allow users to change their own password Signup and view all the answers

What is the purpose of the 'x' permission in a Linux directory?

Grant 'pass-through' permission to access and through the directory Signup and view all the answers

The 'ls -l' command shows permissions and details of a file.

True Signup and view all the answers

What option is used with the 'ls' command to show permissions and details of a directory?

-ld Signup and view all the answers

The 'r' permission grants permission to _______________________ the contents of a directory.

read Signup and view all the answers

What is the purpose of the 'w' permission in a Linux directory?

Grant permission to write/edit directory content Signup and view all the answers

Match the following Linux permissions with their descriptions:

r = Grant permission to read the contents of a directory w = Grant permission to write/edit directory content x = Grant 'pass-through' permission to access and through the directory Signup and view all the answers

Write permission on a directory allows removing files in that directory.

True Signup and view all the answers

The 'ls -ld' command shows permissions and details of the _______________________ directory.

current Signup and view all the answers

What is the standard input file descriptor?

0 Signup and view all the answers

The greater than symbol (>) is used to read input from a file.

False Signup and view all the answers

What does the '2>&1' syntax do in the command './myprog >myoutput.txt 2>&1'?

It sends standard error output to the same place as standard output. Signup and view all the answers

The shell uses special characters and syntax on command lines to implement I/O _______________________.

redirection Signup and view all the answers

Match the file descriptors with their standard streams:

0 = Standard Input 1 = Standard Output 2 = Standard Error Signup and view all the answers

What is the purpose of the '>>' symbol in the command 'tr '[A-Z]' '[a-z]' lowercase.txt >> output.txt'?

To append to the output file Signup and view all the answers

The 'less than' symbol (<) is used to write output to a file.

False Signup and view all the answers

What is the purpose of the '2>' syntax in the command 'gcc -o myprog myprog.c 2>gccerrors.txt'?

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

The shell provides convenient ways to attach the file descriptors to _______________________, devices, or other commands.

files Signup and view all the answers

What is the purpose of the '>' symbol in the command 'tr '[A-Z]' '[a-z]' lowercase.txt > output.txt'?

To write output to the file Signup and view all the answers

What is a key aspect of the Unix philosophy?

Write programs to work together Signup and view all the answers

In Unix, commands can only read input from files.

False Signup and view all the answers

What is the universal interface in Unix?

text streams Signup and view all the answers

Commands can send their output to files or other commands instead of displaying it on the _______________.

terminal Signup and view all the answers

Match the following concepts with their descriptions:

Input/Output Redirection = Sending output to files or commands instead of the terminal Pipes = Connecting commands to work together Filters = Commands that read input, process or modify it, and send it along as output Signup and view all the answers

What is a characteristic of Unix/Linux commands?

They can work together as filters Signup and view all the answers

Error messages are typically printed on the terminal.

True Signup and view all the answers

What is the term for redirecting output or error messages to files or commands?

Input/Output Redirection Signup and view all the answers

In Unix, commands can get their input from _______________ or the terminal.

other commands Signup and view all the answers

What is a key concept in Unix philosophy?

Write programs to work together Signup and view all the answers

What is the purpose of "/dev/null" in Linux?

To ignore any output or errors Signup and view all the answers

Commands can send their standard output directly to the standard input of another command. (True or False)

True Signup and view all the answers

What is the magic of pipes in Linux?

The ability to connect the output of one command to the input of another command without creating intermediate files. Signup and view all the answers

The shell uses the ______ system call to connect the necessary file descriptors before running commands.

pipe(2) Signup and view all the answers

Match the following Linux filter commands with their descriptions:

sort = sorts lines of text cut = extracts columns from a file more = displays a file one page at a time less = displays a file one page at a time Signup and view all the answers

What is the purpose of the "|" pipe operator in Linux?

To connect two commands together Signup and view all the answers

Commands must be chained in a specific order when using pipes in Linux. (True or False)

True Signup and view all the answers

What is the standard output of a command in Linux?

The output of a command that is sent to the screen or to another command. Signup and view all the answers

The "2>" symbol in the command "grep Linux * 2>/dev/null" redirects ______ to /dev/null.

error messages Signup and view all the answers

What is the benefit of using pipes in Linux?

To make commands more powerful Signup and view all the answers

What is the primary function of the OS in process management?

To manage system resources Signup and view all the answers

The 'ps' command in Linux shows all running processes by default.

False Signup and view all the answers

What is the purpose of the 'pstree' command in Linux?

To offer a tree view of process, branching from parent process to child process Signup and view all the answers

The OS keeps track of the ______________ and of the system resources.

processes Signup and view all the answers

Match the following Linux commands with their functions:

ps = Offers a snapshot of processes pstree = Offers a dynamic real-time view of processes top = Offers a tree view of process, branching from parent process to child process Signup and view all the answers

What is an important concept in all operating systems?

Process Management Signup and view all the answers

The 'top' command in Linux offers a snapshot of processes.

False Signup and view all the answers

Why is it crucial for system administrators to monitor processes?

To know which processes are running, their current state, resources they use, and which user started them Signup and view all the answers

During the lifetime of a process, it uses many system resources like ______________ and memory.

CPU Signup and view all the answers

What is the primary benefit of process management in operating systems?

To manage system resources fairly Signup and view all the answers

What is the command to display all processes of the current user?

ps x Signup and view all the answers

The 'ps' command only displays processes that are currently using the CPU.

False Signup and view all the answers

What is the state of a process that is waiting for its parent process to retrieve its exit code?

Zombie Signup and view all the answers

The 'pstree' command shows a tree view of all current _______________.

processes Signup and view all the answers

What is the purpose of the 'top' command?

To provide a dynamic view of what's going on Signup and view all the answers

Foreground processes are initiated by the system and run in the background.

False Signup and view all the answers

What is the command to display process information of a specific user?

ps -u username Signup and view all the answers

Match the following process states with their descriptions:

Running = currently using the CPU Sleeping = waiting in queue to use the CPU Stopped = stopped (but not terminated), either by user or other process Zombie = terminated but is waiting for its parent process to retrieve its exit code Signup and view all the answers

The 'ps' command displays information about processes, including _______________, TTY, Time, and CMD.

PID Signup and view all the answers

All processes in Linux are initiated by the 'systemd' process.

True Signup and view all the answers

What type of processes usually run in the background?

System-related processes Signup and view all the answers

Foreground processes do not take away the command line until the process is finished.

False Signup and view all the answers

How can you start a process in the background?

By appending '&' at the end of the command line. Signup and view all the answers

To send a process to the background while also stopping it, you can press ______ and then the 'bg' command.

Ctrl+Z Signup and view all the answers

Match the following process types with their characteristics:

Foreground processes = Take away the command line until the process is finished Background processes = Run non-interactively and do not expect user input System-related processes = Usually run in the background and are called daemons User-initiated processes = Run in the foreground by default Signup and view all the answers

What is the purpose of the 'kill' command?

To send signals to processes Signup and view all the answers

The 'kill' command can kill multiple processes at once.

False Signup and view all the answers

What is the syntax for the 'kill' command?

kill PID (PID or %job) Signup and view all the answers

To start a process in the foreground, you can simply run the command ______.

normally Signup and view all the answers

What happens when you press Ctrl+Z and then the 'bg' command?

The process is sent to the background and stopped Signup and view all the answers

What happens when you press Ctrl+Z in the terminal?

The current process is stopped and returned to the shell prompt Signup and view all the answers

The kill command can only send the TERM signal to a process.

False Signup and view all the answers

What is the purpose of the jobs command?

To show stopped and background processes. Signup and view all the answers

The bg command is used to move a job to the _______________________.

background Signup and view all the answers

Match the following commands with their functions:

bg = Move a job to the background fg = Move a job to the foreground jobs = Show stopped and background processes kill = Send a signal to a process Signup and view all the answers

What is the purpose of the kill -9 command?

To send a signal to a process to terminate it instantly Signup and view all the answers

Process management is not an important component of an operating system.

False Signup and view all the answers

What is the purpose of the fg command?

To move a job to the foreground Signup and view all the answers

The _______________________ signal is sent to a process by default when using the kill command.

TERM Signup and view all the answers

You can only send two types of signals to a process using the kill command.

False Signup and view all the answers

What is monitored in the Details tab of Task Manager?

Process states Signup and view all the answers

Windows PowerShell provides commands for managing processes.

True Signup and view all the answers

What is the purpose of the Get-Process command in PowerShell?

Get a list of running Windows processes Signup and view all the answers

The Set Affinity option is used to set the ______________________ priority of a process.

CPU Signup and view all the answers

Match the following PowerShell commands with their functions:

Get-Process = Get a list of running Windows processes Start-Process = Start a process/program Stop-Process = Forcibly stop (kill) a process Debug-Process = Debug a process Signup and view all the answers

What can be done to a specific process by right-clicking on the process name?

All of the above Signup and view all the answers

Process management is not an important component of every operating system.

False Signup and view all the answers

Why should users monitor the processes?

For better system performance Signup and view all the answers

Monitor resource usage includes monitoring ______________________ usage.

CPU, Memory, Disk, Network, GPU Signup and view all the answers

What can be used to monitor a specific process?

All of the above Signup and view all the answers

What is the term used in Windows for a process?

Task Signup and view all the answers

In Windows, the Task Manager is used to monitor threads.

False Signup and view all the answers

What is the function of the CreateProcess() function in Windows?

To create a new process Signup and view all the answers

In Windows, the ___________________ function is used to wait for a process to finish.

WaitForSingleObject() Signup and view all the answers

Match the following Windows functions with their descriptions:

CreateProcess() = Create a new process WaitForSingleObject() = Wait for a process to finish CloseHandle() = Close a process handle Signup and view all the answers

What is the hierarchical structure of processes in Windows?

Parent-child Signup and view all the answers

In Windows, all processes run as the same user.

False Signup and view all the answers

What is the primary interface for monitoring processes in Windows?

Task Manager Signup and view all the answers

In Windows, the ___________________ function is used to close a process handle.

CloseHandle() Signup and view all the answers

What is the Microsoft documentation resource for process management in Windows?

<a href="https://learn.microsoft.com/en-us/windows/win32/procthread/processes-and-threads">https://learn.microsoft.com/en-us/windows/win32/procthread/processes-and-threads</a> Signup and view all the answers

Study Notes

User Interfaces

Command Line Interfaces (CLI) are used in Windows, Linux, and Android
Graphical User Interfaces (GUI) are used in Windows and Linux
GUIs are well-suited for graphical tasks, but may require excessive repetitive actions
CLIs are well-suited for automation, but not for occasional tasks
GUIs require more data than CLIs (e.g., 6 megabytes vs. 2 kilobytes)

GUI vs CLI

GUIs are suitable for graphical tasks, such as editing images and documents
CLIs are suitable for automation, such as mass-conversion of thousands of images
GUIs require more data than CLIs, making CLIs suitable for remote connections

Text User Interfaces

A Text User Interface (TUI) employs the same display technology as a CLI, but presents a full-screen interface
TUIs were dominant in personal computers before Microsoft Windows and Apple Macintosh
TUIs are still common in traditional business applications, such as banking

A Bit of History

In the early days of computing, standardization was impossible due to unique computers
One customer of a cloud server should not be able to access another customer's data
Multiple smartphone apps may be permitted to access a single photo album

Hardware Abstraction

The OS hides hardware details so that application software can deal with hardware consistently
Examples: a program can request input from a keyboard without knowing the connection, and an application can send data to the network regardless of the connection type

Maintaining the Programming Model

The OS controls the hardware to maintain the illusion of the programmer's model
Example: multiple programs can operate simultaneously without conflict, using the hardware virtual memory system to load programs into different regions of physical memory

The User Interface(s)

The user interface is the software that enables the user to interact with the system
Most operating systems provide at least two types of user interfaces: text-based (CLI) and graphical (GUI)

Components of an Operating System

The four key components of an operating system are:
- The Kernel
- System Libraries
- Services
- User Interface(s)
- Utilities and Applications

The Kernel

The kernel is the heart of the operating system, operating in a special privileged mode
The kernel manages resources and security settings for all other software
The kernel is loaded by the computer's firmware and initializes the hardware and resources

System Libraries

System libraries provide a common set of software routines for programs to access
These libraries eliminate the need for duplicate code in programs for common operations
Examples: drawing on the screen, accessing the network, and playing sound

Services

Services are programs that run continuously in the background, providing services such as WiFi authentication, print management, and file sharing

Unix and Unix-like Operating Systems

Unix became a trademark, and any operating system that conforms to the Unix standards can use the Unix trademark.
Apple's MacOS is officially a Unix system, but Linux is not.
Unix-like operating systems include Linux, Mac OS, iOS, FreeBSD, OpenBSD, and NetBSD.

Operating Systems in this Course

The course focuses on two operating systems: Windows 10 (a proprietary operating system) and Linux (representing Unix-like operating systems).
Windows 10 is installed on the lab computers, and Linux is available through a remote connection to a server called Matrix.

Command Line and Commands

A Command Line Interface (CLI) is provided by two components: a terminal program and a shell.
The shell interprets commands, starts and stops programs, and displays output.
Common shells include Bash, PowerShell, and CMD.

What is a Command?

A command is a small program that performs a specific task.
Commands can be built into the shell or be separate programs.
Examples of commands include the Chrome web browser, git version control tool, and LibreOffice Writer word processor.

Command Structure

Most commands have a similar structure: command_name arguments.
The command_name is the name of the command, and the arguments are options, values, or positional arguments.

Types of Arguments

Option (or switch or control argument): alters the operation of the command.
Option with a value: consists of an option followed by a value.
Positional arguments: all other arguments, where the position may be significant.

Options – Examples

ls command: lists files, with options like -l for long output.
dir command: lists files, with options like /b for bare output.

Options – Long and Short Versions (Linux)

ls -l -h : shows human-readable sizes.
ls -l --human-readable : same as above.
ls -lh : same as above.

Option with a Value

ls -l -sort=size : sorts files by size (Linux).
ls -l -sort time : sorts files by time (Linux).

Positional Arguments

cp old new : copies file "old" to "new" (Linux).
copy old new : copies file "old" to "new" (Win10).

Open Source and Proprietary Software

Software is protected by copyright, and the copyright holder controls how it is used.
There are two broad categories of software licenses: proprietary licenses and open source licenses.

Open Source Licenses

Open source licenses conform to the Open Source Definition (https://opensource.org/osd/).
There are two types of open source licenses: free software licenses and permissive licenses.

Types of Open Source Licenses

Free software licenses: require redistributing software under the same terms as received.
Permissive licenses: allow redistributing software without the same permissions as received.

Course Introduction and Overview

OPS102 is a course about Operating Systems for Programmers, covering both Linux and Windows.
The course is designed for software developers and replaced ULI101 for SDDS students.
The course breakdown includes labs (20%), quizzes (25%), mid-term test (25%), and final test (30%).

Matrix and Connecting to Matrix

Matrix is a server cluster with multiple computers running CentOS (a version of Linux).
All registered students in OPS102 have access to an account on Matrix.
To connect to Matrix, you must be on campus or connected to SenecaNet, or off campus with Seneca VPN.
You can connect to Matrix from any Seneca lab workstation or personal computer using SSH (secure shell).
SSH is a protocol for secure remote login/connection from one computer to another.

Simple Commands to Start With

Simple commands to practice on Matrix include basic Linux commands.

Hierarchical File Systems

A file system location is found by following the directory tree hierarchy.
There are multiple ways of specifying pathnames: absolute, relative, and relative to home.
Absolute pathnames start from the root of the hierarchy, while relative pathnames do not start with a slash.
Relative to home pathnames use a tilde (~) as a shorthand for the user's home directory.

Practicing Linux Commands and File Systems

You will practice Linux commands and perform lab exercises on Matrix.
You will reference your Matrix account during quizzes and tests.

Troubleshooting Connection Issues

Common connection issues include mis-spelled username, password, or hostname.
Ensure that your username is in lowercase and CAPS LOCK is off.

Connecting to Matrix Using PuTTY (Windows) or Terminal (MacOS/Linux)

Download and install PuTTY on Windows, or use the Terminal app on MacOS/Linux.
Set up PuTTY with the host name "matrix.senecapolytechnic.ca", port 22, and connection type SSH.
On MacOS/Linux, use the SSH command to connect to Matrix.

Files in Linux/Unix

Data is saved in files, and Linux/Unix systems prefer text files.
Files are used for data, presentations, configuration, logs, and more.
The system and shell provide easy ways to deal with files.

Learning About Commands

Extensive documentation is available on Linux/Unix systems using the "man" command.
The "man" command provides access to most documentation, which is divided into sections.
Man pages can be accessed using the command "man man".

File and Directory Operations

Important file management skills include creating and deleting files and directories, reading file contents, copying files, moving or renaming files, and viewing file contents without editing.
These operations can be performed using various commands:
- Creating directories: mkdir (Linux/Unix) and mkdir (Windows)
- Moving files and directories: mv (Linux/Unix) and move (Windows)
- Copying files and directories: cp (Linux/Unix) and copy (Windows)
- Deleting files and directories: rm (Linux/Unix) and del (Windows)
- Removing empty directories: rmdir (Linux/Unix) and rmdir (Windows)
- Recursive directory removal: rm -r (Linux/Unix) and deltree (Windows)

Directory Operations

The "cd" command is used to change directories.
The "pushd" and "popd" commands are also used to manipulate directories.
The "mkdir" command creates one or more directories, and the "-p" option ensures the path/parents exist.
The "rmdir" command removes one or more empty directories.

File Operations

Files can be created using a text editor or output from program output redirection.
The "touch" command creates an empty file or updates the file's timestamp.
The "cp" and "mv" commands copy and move files, respectively.
The "rm" command removes files, and the "-r" option removes directories recursively.

Working with Text Files

Linux/Unix systems have many tools for working with text files, including:
- cat and copy file con: (Windows) to display the contents of a file.
- more and less to display the contents of a file one screen at a time.
- head and tail to display the beginning or end of a file.
- file to determine the type of file.
Windows typically requires add-on programs for most of these operations, or the use of WSL (Windows Subsystem for Linux).

Working with Text Files (cont'd)

Additional tools for working with text files include:
- sort to sort the lines of a file.
- uniq to display identical consecutive lines only once.
- cut to remove undesired columns from data in a file.
- tr to translate/replace the occurrences of characters.
- grep to find specific lines in a file.
- find to find files matching specific criteria in the filesystem.
- diff to show the differences between two files.

File Globbing

File globbing is a feature provided by the shell, allowing the use of special characters called wildcards to write a generic name that the shell will expand into specific matching names.
Wildcards include:
- * to match any characters.
- ? to match any one character.
- [ ] to match any one of the characters contained in the class.
- ! to invert the character class and match any character not listed.

File Globbing Examples

* can be used to expand into a list of files and directories, such as img001.jpg, imgface.jpg, and img500.jpg.
? can be used to match files with a specific pattern, such as File?.pdf to match files starting with File, followed by any one character, and ending with .pdf.
[ ] can be used to match files with a specific pattern, such as ls File[123].pdf to match files starting with File, followed by any one of the characters 1, 2, or 3, and ending with .pdf.

What is a Text File?

A text file is a file that contains data in a human-readable format.
In Linux/Unix, text files are widely used for data, presentations, configuration, logs, and more.
The system and shell provide "easy" ways to deal with files.

Line Endings in Text Files

Each line in a text file has an end-of-line indicator.
In UNIX/Linux, the end-of-line indicator is a "new line" (line feed or ^J or \n).
In Windows, the end-of-line indicator is a "carriage return" (^M or \r) followed by a "line feed".
In MacOS, the end-of-line indicator is a "carriage return" (^M or \r).
When text files are transferred between systems, there could be problems.

Text Editors

A text editor is a software that allows users to create, modify, and save editing changes to text files.
Text editors are essential for programmers and administrators in Unix and Linux systems.
Text editors are used for editing system configuration files, writing scripts and programs, writing/editing documentation, and developing web pages.

Text Editors – History

Before video terminals, "line editors" were used, such as qed, ed, and edlin (DOS).
The ed(1) editor was replaced by ex(1) on Unix, which later evolved into vi(1).
The vi(1) editor originated from Bill Joy at UCBerkeley and first appeared in BSD.

Text Editors – Many Choices Today

There are many text editors available in Linux and Windows, such as VIM, Nano, Gedit, Notepad, Notepad++, and Sublime.

Nano Text Editor Introduction

The Nano text editor is an easy-to-use text editor installed on many Linux systems.
Nano editing commands typically use control characters.
The menu is always displayed at the bottom of the nano screen.

More About Nano

Basic Nano commands include:
- ^G – to get help at any time
- ^R – open a file
- ^O – save a file
- ^W – find
- ^\ – replace
- ^X – exit

Nano vs Vi

The vi(1) command is often actually vim(1), which adds modern features to classic vi.
For casual, occasional use, the nano editor is fine.
For anything beyond the basics, it's recommended to become familiar with vi (or vim).

File System Security: Permissions

In multi-user operating systems, controlling access to files and folders is crucial, and this is achieved by setting permissions.

How Does setuid/setgid Work?

setuid allows a program to run with the permissions of the file owner, enabling it to perform actions that would typically require the owner's privileges.
An example of setuid in action is the "passwd" command, which allows users to change their own passwords without requiring "sudo" access for root user permissions.

The Sticky Bit

The sticky bit is a special permission that can be set on directories, ensuring that only the owner of a file or the root user can delete or rename the file.
The main purpose of the sticky bit is to ensure the privacy and security of files in shared directories.

Default Permissions and Umask

umask is an attribute of a process that is inherited by child processes, and is normally set at shell start-up.
umask "masks off" (disables) permission bits for any files or directories created by the process.

File Permissions in Linux

Every file and folder in the file system has its own set of permissions, which determine who may access a file, and in what way(s).
There are three permission indicators: user (u), group (g), and others (o).
Permissions include:
- Read (r): allows reading the file's contents.
- Write (w): allows modifying the file's contents.
- Execute (x): allows executing the file as a command, and scripts also need read permission to execute.

Directory Permissions in Linux

Directory permissions are similar to file permissions, but have slightly different meanings.
Permissions include:
- Read (r): grants permission to read the contents of the directory, and list contents using the "ls" command.
- Write (w): grants permission to change or edit the directory content, and create or delete subdirectories and files.
- Execute (x): allows access to and through the directory, but does not in itself allow reading or writing.

Viewing Permissions

The "-l" (long) option to "ls" shows permissions and other details about files and directories.
The "ls -d" command on a directory shows the directory, not its contents.

Setting Permissions

The "chmod" (change mode) command is used to change or grant permissions to different users or groups.
There are two methods to set permissions with "chmod": the symbolic method and the octal method.

Symbolic Method for "chmod"

Permissions are set for user (u), group (g), others (o), or all (a).
Permissions are set by adding (+), removing (-), or setting (=) read (r), write (w), and/or execute (x) permissions.

Octal Method for "chmod"

Permissions can be set explicitly by "chmod" with an octal number.
Octal numbers represent the permission bits, with read = 4, write = 2, and execute = 1.
Combine the octal representation of user, group, and other permissions to form a 3-digit octal number.

Standard Input, Output, and Error

Every program or command has three open file descriptors: 0 (standard input), 1 (standard output), and 2 (standard error output).
These file descriptors can be attached to files, devices, or other commands.

Input/Output Redirection and the Shell

The shell uses special characters and syntax to implement I/O redirection.
< is used to read input from a file.
> is used to write output to a file, overwriting the file if it exists.
>> is used to append output to a file.
I/O redirection can be used with any command, but it may not be useful with some commands (e.g., "date").

Redirecting Error Output

The standard error output can be redirected using 2> or 2>>.
2>&1 sends the standard error output to the same place as the standard output.

Input/Output and "/dev/null"

/dev/null is a special file that can be written to or read from, but the data is discarded.
/dev/null is useful for ignoring output or error messages.

Connecting Commands with Pipes

Pipes connect the output of one command to the input of another command.
The | operator is used to create a pipe between commands.
Commands can be chained together in a specific order to achieve a specific task.

The Unix Philosophy

The Unix Philosophy states that programs should:
- Do one thing and do it well.
- Work together.
- Handle text streams, which is a universal interface.
Many Linux/Unix commands act as filters, reading input, processing or modifying it, and sending it as output.

Process Management

Process management is crucial in operating systems, where programs executing are referred to as processes
The OS keeps track of processes and system resources to manage them fairly

Monitoring Processes

System administrators need to monitor:
- Which processes are running in the system
- The current state of the processes
- Resources these processes are taking
- Which user started which process
Tools for monitoring processes:
- "ps" command: offers a snapshot of processes
- "pstree" command: offers a tree view of process, branching from parent process to child process
- "top" command: offers a dynamic real-time view of processes

The "ps" Command

Displays all processes of the current user by default
Options:
- "-e" displays all processes currently running
- "aux" displays user-oriented variant, all processes
- "-u username" displays process of a user named username
Columns description:
- PID: Process ID
- TTY: The terminal that controls the process
- Time: the number of hours, minutes, and seconds the process has been running
- CMD: the command line, the process was called with

Process States

Processes in Linux can exist in four different states:
- (R)unning: currently using the CPU
- (S)leeping: waiting in queue to use the CPU
- s(T)opped: stopped (but not terminated), either by user or other process
- (Z)ombie: terminated but waiting for its parent process to retrieve its exit code

The "pstree" Command

Shows a tree view of all current processes
Processes are always instantiated by other processes
Your system starts with the "systemd" process
Parent processes start child processes

The "top" Command

Provides a dynamic view of what’s going on
Shows process listed according to CPU usage
Shows memory usage and status

Process Control

Two types of processes in Linux:
- Foreground: interactive, initiated by a user and controlled through terminal session
- Background: non-interactive, not connected to a terminal

Starting a Process

Once you run a command or program, it will start a process in the system
You can start a process in the background by appending "&" at the end of the command line
System-related processes usually run in the background and are called daemons

Terminating (Signalling) a Process

The "kill" command is used to send signals to processes
Syntax: "kill PID" (PID or %job)
The kill command sends signals to processes, including the terminate signal
Many different signals are available
- Ctrl+Z sends the TSTP (terminal stop) signal

Jobs – Foreground, Stopped, Background

The shell starts processes and allows you to stop/re-start and foreground/background processes (jobs)
Ctrl+Z stops the currently active foreground job and returns you to the shell prompt
The jobs command shows stopped and background processes
bg moves a job to the background, fg moves to foreground
Add a job number to affect a particular job e.g. bg %2

Process Management in Windows

Monitor resource usage: CPU, Memory, Disk, Network, and GPU.
The Details tab of Task Manager shows the process states.

Process Control in Windows

When an application is started, a process is created, which can be viewed in the Task Manager.
Right-clicking on the process name shows actions that can be taken on the specific process, including:
- End task
- Set Priority
- Set Affinity

Managing Processes Using PowerShell

Windows PowerShell provides the following commands for managing processes:
- Get-Process: Get a list of running Windows processes
- Start-Process: Start a process/program
- Stop-Process: Forcibly stop (kill) a process
- Debug-Process: Debug a process
- Wait-Process: Wait until a process ends
Monitoring processes using Get-Process, and monitoring a specific process using Get-Process.

Process Management Recap

Everything that runs on a computer is a process.
Processes in Linux are hierarchical - every process has a parent.
Tools like "ps", "pstree", and "top" are used to manage processes.
The shell allows foreground, stopped, and background processes.
Signals can be sent to processes with the "kill" command.

Processes in Windows

Windows generally says "task" rather than "process".
A hierarchy of parent and child processes exists, and tasks can run as different users.
In code, CreateProcess(), WaitForSingleObject(), and CloseHandle() are used.
Microsoft documentation provides more information on processes and threads.

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