220-1202 Operating Systems Study Guide for the CompTIA A+ Core Series Exam

Linux OS Desktop

The Linux client/desktop OS has its own set of OS-specific common features and tools that you must be able to identify.

File Management

File Management commands on the Linux OS are used to access and manage files using the command-line interface. You should be familiar with these:

• ls—The ls command is known as the list command in Linux. This is because the command will list all the files or folders in a given directory. In order to use this command, navigate to the folder or directory you’re interested in and type “ls”. After hitting enter, a list of all the files and folders in that location will be displayed.

• pwd—While many people see the term pwd and think “password,” it actually means something very different in Linux. The pwd command stands for present working directory, and it displays the full path of the current working directory.

• mv—The mv command in Linux is the move command. This command allows a user to move a specified file to another location. Move is similar to a cut-and-paste command in Windows.

• cp—The cp command in Linux stands for copy. Its functionality is similar to that of the move file, except that it places a copy in the new location while leaving the file in the original location.

• rm—The rm command stands for remove in the Linux OS. This is similar to deleting, as it removes the file, directory, or other objects from the location.

• chmod—To modify Linux file permissions, you must use the chmod command. Before changing Linux file permissions, it’s important to first understand how they are represented. Each permission is represented by a letter: r–read permission; w–write permission; x–execute permission.

• chown—Just as the chmod command changes the permissions, the chown command changes the ownership of a file, directory, or other objects.

• grep—The grep command is a search command and stands for global regular expression print. You can use it to search for a string of characters within a file or standard text output. For example, if you are viewing a file in the terminal and type the grep “unix” command, the terminal will display all of the instances of the word “unix” in that file.

• find—The find command can be used for searching for specific text within a file hierarchy.

File System Management

The file system on a Linux OS is used for file management and organization, utilizing a hierarchical structure. These file system management commands are used to access and configure file systems:

• fsck—The fsck command is used to check for and repair inconsistencies in the file system. This command is often deployed during the boot process but may also be manually deployed if needed, such as if corruption is suspected.

• mount—The mount command is used to connect a file system to a directory, allowing user and OS access. Additional instructions, such as file system type and read/write permissions, can also be added using this command. Conversely, the umount command is used to detach a file system from a directory.

Administrative

These administrative commands are used to manage a Linux OS’s users, groups, or system:

• su—The su command stands for switch user (or substitute user). This command can be used by adding a username that you wish to switch to after the command (e.g., su linuxuser1), or it can be used by itself, which will switch it to the root user by default.

• sudo—The sudo command switches the user for only a single command, whereas su switches the user until it’s switched back.

Package Management

Package management command tools are used to manage software packages, including installing, updating, and removing the package and associated dependencies. A dependency is additional software packages or libraries required by a package for functionality. You should know these commands:

• apt—APT stands for “advanced packaging tool” and is used in conjunction with flags for handling packages in some Linux distributions, primarily Ubuntu. For example, the apt-get command launches a tool used to retrieve packages from authenticated sources for the installation, upgrading, and removal of packages, along with their dependencies.

Note: The latest research indicates that apt-get is not deprecated and is still used in operations like scripting. That said, apt (e.g., apt install) is the newer method that is suggested to be used for newcomers to the field. The apt-get command may still be used by more experienced Linux admins (mostly out of habit).

• dnf—The dnf command, otherwise known as the Dandified YUM command, is a package management tool available on some Linux OS distributions, including Fedora and Red Hat, which is used for the simplified installation, updating, and removal of software packages and related dependencies.

Network

Network commands on the Linux OS, such as the following, are used to manage, monitor, and configure network connections:

• ip—The ip command is used to display and configure information related to a network interface card (NIC). The ip command has replaced the previously used ifconfig command on the Linux OS.

• ping—The ping command on the Linux OS provides the same functionality as on the Windows OS and tests for network connectivity.

• curl—The curl command is used for data transfer with URLs. The curl command is compatible with multiple protocols, including HTTP, HTTPS, FTP, and SFTP.

• dig—The dig command is used in networking and is a DNS query utility.

• traceroute—The traceroute command is used to follow a packet from the source to the destination and is useful for providing insight into network connectivity issues.

Informational

Informational commands are used to identify, display, and manage data related to the system, files, or users on the Linux OS. You should know these commands:

• man—The man command displays system help for executable files.

• cat—The cat command displays the contents of a file.

• top—The top command displays a list of running processes.

• ps—The ps command (which stands for process status) displays all of the currently running processes and their process numbers.

• du—The du command (disk used) is used to identify the amount of disk space used by individual files or directories.

• df—The df command (disk free) is used in processing files and displays the total free disk space for a directory.

Text Editors

A text editor command is used to navigate, manage, and manipulate text files on the Linux OS. You should know this command for this test:

• nano—The nano command is a text-based editor for files.

Common Configuration Files

Most Linux configuration files are stored in the /etc directory. Configuration files are used to house data related to different aspects of the OS, installed applications, and available services. These are file types you should know:

OS Components

The core components of the Linux OS are the underlying systems and processes responsible for the overall functionality of the OS. The core components work together during the boot process to load the Linux OS in the following order: the firmware loads first using BIOS or UEFI, the bootloader initiates next, which launches the kernel, and that is followed by systemd.

• bootloader—The bootloader is the software responsible for retrieving the kernel from the storage location after the firmware loads, most commonly using either BIOS or UEFI, and loading it into the device’s memory, allowing the OS to launch. The bootloader essentially takes control of the system after the BIOS or UEFI runs and transfers control to the OS kernel.

• kernel—The kernel is the primary component of the Linux OS, providing communications between hardware and software components. The kernel also manages critical tasks such as managing and allocating hardware resources like CPU and RAM usage.

• systemd—Systemd is the init system, also known as the process ID 1 (PID1), which runs after the kernel and initiates other services and processes on the system during boot and operation. Systemd acts as the system manager for services, organizing resources into easily managed units. The systemctl command is used to interact with systemd.

Root Account

The root account, also known as the superuser, on a Linux OS is the most privileged user on the system and has completely unrestricted access. The root account, with the designated user ID of UID 0, bypasses all security restrictions and should be used with extreme caution. To enhance security while using root account privileges, the sudo command can be used.

Application Installment

There are multiple methods for installing new applications and software, as well as a number of considerations to ensure installation is completed successfully. You must be able to apply the following installation and configuration concepts. Questions on these concepts will be scenario-based.

System Requirements for Applications

Before you install any new applications, you must ensure the system has sufficient resources to support the installation. The specific requirements depend on the application and can usually be found in the supporting documentation for the application.

32-bit vs. 64-bit Application Requirements

Application requirements must match the architecture of the CPU and OS for either 32-bit or 64-bit architectures. However, if the architecture supports 64 bits, it will be able to properly run 32-bit applications.

Dedicated vs. Integrated Graphics Card

A dedicated graphics card, also known as a discrete graphics card, is a separate hardware component designed specifically for rendering graphics and display tasks. In contrast, an integrated graphics solution is typically built directly into the CPU of modern computers, although some older systems might have it on the motherboard. It’s essential to ensure that the graphics solution, whether integrated or dedicated, meets the requirements of the applications and OS being used.

Random-Access Memory (RAM) Requirements

To run an application, it needs to be loaded into memory. If there is insufficient RAM available, the application will run slowly, slowing down other processes, or it will not be able to run at all.

Video Random-Access Memory (VRAM) Requirements

The VRAM requirements are for graphics-intensive applications, such as gaming. For the application to function properly, the device’s VRAM requirements must be met by the program.

Central Processing Unit (CPU) Requirements

The CPU requirements of an application are typically given in gigahertz (GHz) and show the amount of processing power the application requires. The system must meet or exceed these requirements for proper functionality.

External Hardware Tokens

External hardware tokens are physical devices that can be connected to the device for increased security. The requirements for the hardware token must be met or exceeded by the host computer.

Storage Requirements

Before running an application, its files need to be stored on the computer’s disk. There should be enough free disk space to copy and use the program’s files.

Application to OS Compatibility

The application needs to be compatible with the host OS. Many applications come in various OS-compatible versions, so make sure you are installing a Windows-compatible application on a Windows OS, for instance. Applications that require a 64-bit OS will not be compatible with a 32-bit OS, but a 32-bit application will be compatible with a 64-bit OS.

Distribution Methods

There are multiple ways to distribute software installation files. You should be familiar with all of these and comfortable using them in a real-world situation.

Physical Media vs. Mountable ISO File

The only way to install new software on a computer that is not connected to any network is to have the application on a portable media, CD, or USB disk. This can also be useful for large applications or slow networks. The installation files can be run directly from the media or be copied to the hard disk first and then installed. A mountable ISO application installation is one in which the application ISO is downloaded from the vendor and installed directly onto the host machine to act as a virtual optical drive.

Downloadable Package

On computers connected to a network, applications can be installed remotely over the network, rather than being downloaded from portable media or local files. If the application is downloaded from the internet, the files are first copied to the local disk and then installed. OSs also include forms of application stores and repositories that make it easy to find and install new software.

Image Deployment

Image deployment is the process of using a copy, or image, of a reference device to create multiple devices with identical OSs, configurations, applications, and settings. An image can be deployed using either physical media, such as a USB drive, or through a network connection.

Impact Considerations for New Applications

When a new application is installed on a device or system, unintended consequences may occur, impacting not only the device itself but also other components and operations connected to the network.

Device

Installing a new application may allow it access to other files on the computer. Some software can be malicious and may require research before installation. Even if there are no ill intentions, some software functions may not be suitable for protected corporate environments with sensitive information.

Network

If a new application is installed on a computer connected to the network, it will effectively gain access to the network. It may compromise the security of other computers on the same network.

Operation

New applications can affect the operations of the OS and its information system. These effects can be negative and may compromise the efficiency of the computer.

Business

Before installing new applications on a computer connected to a business network, the effects of the application should be considered and evaluated for potentially harmful effects to the business.

Cloud-Based Productivity Tools

Cloud-based productivity tools are software, systems, and platforms that are hosted in a cloud environment, enabling interaction by multiple users from any location attached to the hosting network, such as the internet. For the CompTIA A+ exam, you must be able to identify, install, and configure common cloud-based productivity tools. Questions in the section will be scenario-based.

Email Systems

Cloud-based email systems are third-party email systems hosted on cloud servers that provide complete emailing capabilities and synchronization across an internet connection. Cloud-based email systems place the responsibility for the infrastructure and security of the email system on the host. Common cloud-based email systems include Gmail, Outlook, iCloud, Microsoft 365, and Amazon SES.

Storage

Cloud-based storage services, also known as cloud storage, offer digital data storage to users, along with data management and sharing through a third-party provider. Cloud storage enhances ease of accessibility, cost-effectiveness, and scalability, and it is available in public, private, and hybrid cloud configurations. Common cloud-based storage services include Google Drive, Dropbox, OneDrive, iCloud Drive, and Amazon S3.

Sync/Folder Settings

Sync/folder settings in cloud-based storage services are used to define how, when, and where data is stored and shared in the cloud. For example, the sync folder provides automatic upload and synchronization of all data within the folder to the cloud, providing access to all connected devices. Selective sync is a feature that allows users to choose which files will be synced and shared to the cloud. Synchronization of folders can be either two-way sync, where changes on any device are reflected on all other devices, or one-way sync, where only changes made in one direction are reflected.

Collaboration Tools

Cloud-based collaboration tools are platforms that allow for real-time usage and interaction between the platform and multiple users simultaneously. Cloud-based collaboration tools provide centralized storage and ease of accessibility with an internet connection (not dependent on location), as well as project management and communication features within the platform.

Spreadsheets

A spreadsheet is an organizational document that arranges data in columns and rows, which can be manipulated, searched, and sorted based on specified parameters. Common cloud-based spreadsheet collaboration tools include Google Sheets and Microsoft Excel Online.

Videoconferencing

Cloud-based videoconferencing and collaboration tools enable real-time video and audio communication via an internet connection. Videoconferencing tools often include additional functionalities such as screen and file sharing, as well as instant messaging. Common videoconferencing tools include Microsoft Teams, Google Meet, Skype, Zoom, and Slack.

Presentation Tools

A cloud-based presentation tool is a platform that is used to create and display data in an easily digestible format, commonly in a slideshow format, via an internet connection, providing real-time access, collaboration, and manipulation to authorized users. Common cloud-based presentation tools include Google Slide, Microsoft PowerPoint Online, and Canva.

Word Processing Tools

A cloud-based word processing tool is a platform that enables the creation, editing, formatting, saving, printing, and manipulation of text-based documents through a cloud-based third-party service. Common cloud-based processing tools include Google Docs, Microsoft Word Online, and Dropbox Paper.

Instant Messaging (IM)

A cloud-based IM tool is a platform that enables real-time text-based communication exchanges between users through a cloud-hosted service. Cloud-based IM service providers commonly offer additional functionality, such as voice and video calls, file sharing, and integration with other common platforms and tools. Common cloud-based IM tools include Slack, Microsoft Teams, Google Chat, and Discord.

Identity Synchronization

Identity synchronization is the process of creating, modifying, and deleting user identities automatically across multiple systems, platforms, and applications. Cloud-based identity synchronization can be used to replicate user identity data from an on-premises directory to a cloud environment, providing the user access to both on-premises and cloud-based resources.

Licensing Assignment

Licensing assignment is the transfer of rights and obligations from one party to another via a predefined usage agreement. Cloud-based licensing assignment is used to manage, distribute, and store licensing agreements in a cloud infrastructure. This allows for the centralization of the management, distribution, and access of licenses to users and groups.