Numeric

$PATH A variable that contains a list of directories that will be searched for executable files when a user enters a command.

2FA See two-factor authentication.

A

absolute path The location of a file or directory that starts from the root of the filesystem and therefore begins with a slash character (/).

accessibility options A feature provided on desktops that makes it easier for individuals with physical limitations to work with the desktop.

address class ranges The primary subnets of Class A, B, C, D, and E networks.

Advanced Package Tool (APT) A package management system for Debian-derived systems that wraps lower-level tools and provides easy searching of remote package sources, including downloading any needed dependencies.

agent In orchestration, a monitoring system that has been installed on the system or component that is being monitored.

agentless In orchestration, a monitoring system that has not been installed on the system but is performed remotely.

AppArmor A security feature that uses MAC (mandatory access control) to provide more secure access to files and directories.

append To write data to the end of current data in a file without overwriting the file. Appending is always adding to and not replacing content.

application data Any data that is associated with the operation of a software application.

archive file A collection of at least one file into a standardized type of container file such as a tar archive, which is a compressed file such as those produced by bzip2 and gzip.

ASCII (American Standard for Information Interchange) A format for encoding letters, numbers, punctuation, spaces, and other characters into numbers between 0 and 255.

attribute In orchestration, a parameter that is used to customize an automation procedure.

autoconfiguration The process of automatically assigning network configurations such as IP addresses, hostnames, gateways, and subnet addresses.

B

back up The process of copying a file or set of files to another location in order to memorialize them in some manner, either as a long-term or short-term backup copy.

bandwidth The maximum amount of data that can travel through media.

Basic Input/Output System (BIOS) The first software that is started when a computer starts on older IBM-compatible computers. Settings in the BIOS can be changed by using the BIOS setup program.

binary log A systemd log that is not text based.

binary package A collection of applications, documentation, libraries, and configuration files that can be downloaded and run without needing to be compiled from source.

BIOS See Basic Input/Output System (BIOS).

block A contiguous chunk or amount of memory. Blocks can be of flexible size and contents.

blocks in A value that represents how many blocks have been received from a block device (such as a hard disk).

blocks out A value that represents how many blocks have been sent to a block device (such as a hard disk).

Boolean logic Operations such as OR and AND that operate on the true and false primitives that computers understand rather than numbers that humans understand.

boot loader A program that is called by the BIOS to start a computer and that takes care of loading the operating system kernel and initramfs.

boot logging The process of logging and then investigating the logs that pertain to the boot portion of a system’s logs.

boot process The set of steps a system goes through from power on to full functioning.

broadcast address A network address on an IPv4 network that is used to send network messages to all hosts on the subnet.

bus A hardware component that allows other components to connect and talk to each other over a single shared connection rather than each component needing a unique connection to every other component.

C

cache In memory management, the area of memory where recently used files are stored. Cache is an important mechanism to speed up reads on servers.

catenate To use output from one command as input to another command, typically through the use of a pipe. The process of catenation creates what is known as a process output chain.

certificate authority A commonly known organization that guarantees the reliability of PKI certificates. A certificate authority provides a certificate that can be used to sign public key certificates.

chain A set of firewall rules that includes both the type and the filtering point.

check in In version control, to send file changes to a repository.

check out In version control, to get a copy of one or more files that are located in a repository.

Chef Software that provides a relatively new method of configuration management; the logical successor to Puppet.

cloud-init The initial bootstrap tool that prepares a VM environment for the more feature-full Chef, Puppet, and other software options.

coldplug Describes a hardware device that needs the computer to be turned off and on to be recognized.

command substitution A shell scripting technique in which a command is run and then injected into another command.

Common Unix Printing System (CUPS) The software responsible for printing on most Linux systems.

conditional A piece of shell code that tests for given conditions and executes different code, depending on the result of the test.

console In Linux, the primary terminal where a user works. The console is also a specific device with the name /dev/console.

convert To alter from one format to another, such as converting uppercase to lowercase or converting a set of characters to another set of characters, as with the sed or tr commands.

cron A service that runs background jobs at scheduled times.

CUPS See Common Unix Printing System (CUPS).

CUPS back end A piece of the Common Unix Printing System that is responsible for sending a processed print job to a printer.

CVE (Common Vulnerabilities and Exposures) A system that provides information about publicly known vulnerabilities.

D

DAC See discretionary access control (DAC).

daemon A process that runs in the background and provides some sort of service, either to the local machine or to remote machines.

DAG See directed acyclic graph (DAG).

database In relational databases, a collection of tables that together are used to store data.

daylight saving time A system by which in summer months, clocks are moved ahead an hour to take advantage of the longer nights. Daylight saving time is a source of frustration for developers and systems administrators.

default chain policy The target to use when no rule in a chain is matched.

default gateway The gateway used by default for a host. See also gateway.

desktop A software program that acts as the interface between users and a GUI environment.

DHCP See Dynamic Host Configuration Protocol (DHCP).

directed acyclic graph (DAG) A check-in technique used in third-generation version control systems.

discretionary access control (DAC) The use of Linux file and directory permissions to limit access to items.

distributed version control system (DVCS) A type of version control system in which an entire project is checked out.

DNAT (destination NAT) A feature of a router in which inbound network packets are forwarded to another host. See also NAT (network address translation).

DNF (Dandified Yum) An updated version of YUM (Yellow Dog Updater).

DNS See Domain Name System (DNS).

Domain Name System (DNS) A system that makes it possible to translate computer names to IP addresses and vice versa. DNS involves several domain levels, resembling a directory structure in a filesystem.

dotted-quad notation An IPv4 address that consists of four octets.

driver A piece of software that allows a kernel to understand how to communicate with a particular device or set of devices.

dual-homed Describing a host that contains two network interface cards, each of which is on a different network for redundancy, performance, and other benefits.

DVCS See distributed version control systems (DVCS).

Dynamic Host Configuration Protocol (DHCP) A protocol that is often implemented by a server that takes care of providing an IP address and other related configuration information to clients. DHCP makes it possible to use systems in a computer network without the need to configure all of them with the required IP address configuration and related parameters.

dynamic linker (ld.so) The library on a Linux system that is responsible for finding dynamic libraries and presenting them to the application that needs them.

dynamic linking The process of sharing library code between applications rather than requiring each application to keep a copy of the library.

E

epoch time In Linux, the number of seconds that have passed since midnight on Thursday, January 1, 1970. Some utilities write epoch time instead of real clock time.

extended partition On MBR disks, a logical partition that performs just like a regular partition and allows a system administrator to exceed the usual maximum of four partitions that can be stored in the partition table.

extension module An optional feature with iptables that allows more functionality than what the default iptables program provides.

F

File System Hierarchy (FSH) A standard that defines which Linux directories should be used for which purpose. Read man 7 hier (the man page for hier in category 7 of the man pages) for a specification of FSH.

File Transfer Protocol (FTP) A software program that allows users to copy files to and from a remote system. Unfortunately, FTP sends data in plain text, making it an unsecure method.

filesystem Both the single virtual disk presented to a Linux system and the layout of files on the disks.

filtering point A component of a firewall where rules are placed.

firewall A software program designed to block or allow network packets.

firewalld A front-end utility designed to make the process of configuring firewalls with iptables easier.

FSH See File System Hierarchy (FSH).

FTP See File Transfer Protocol (FTP).

G

gateway A host that is used to allow hosts to communicate with other networks. Also known as a router.

GECOS A field in the /etc/passwd file that can be used to store personal data about a user on the Linux operating system. Originally stood for General Electric Comprehensive Operating System.

GID (group identification number) A unique number assigned to a group account.

Git A third-generation version control system.

GMT See Greenwich Mean Time (GMT).

GNOME A common desktop. See also desktop.

Gnu Privacy Guard (GnuPG) A software suite that allows users to encrypt data and digitally sign files.

GPT See GUID partition table (GPT).

graphical user interface (GUI) A Windows-based user interface.

Greenwich Mean Time (GMT) The reference time zone by which all other time zones calculate their times. A time zone is defined as being a certain number of hours and minutes ahead of, or behind, GMT.

GUID partition table (GPT) A modern solution for storing partitions on a hard disk, as opposed to using the older MBR partition table. A total of 128 GUID partitions can be created on a hard disk, and there is no difference between primary, extended, and logical partitions anymore.

H

hard link A name associated with an inode, which is used for storing a Linux file and contains the complete administration of the file, including the blocks where the file is stored. A file that doesn’t have at least one hard link is considered a deleted file. To increase file accessibility, more than one hard link can be created for an inode.

hardware The physical components of a computer, such as CPU, RAM, disk, network card, and so on.

hotplug A device that can be inserted and recognized while a computer is running.

I

IaC See infrastructure as code (IAC).

ICMP See Internet Control Message Protocol (ICMP).

infrastructure as code (IAC) The use of software tools to perform orchestration tasks.

init The first process started when the Linux kernel and initramfs have been loaded. From the init process, all other processes are started. In RHEL 7, the init process has been replaced by systemd.

init process The program that is called by the BIOS to start a computer and that takes care of loading the operating system kernel and initramfs.

integrated peripheral A piece of hardware that is part of the motherboard and is not removable or upgradable.

internationalization A software method that involves allowing an application to change out the language used without needing separate versions of the application.

Internet Control Message Protocol (ICMP) A protocol that allows networking devices, such as routers, to send error messages.

Internet Printing Protocol A modern web-based protocol that allows printers to communicate with computers over a network.

Internet Protocol (IP) A protocol that handles the addressing and communication between devices on a network. It defines IP addresses, subnetting, and routing.

IP See Internet Protocol (IP).

IP (Internet Protocol) address An address used to direct network traffic to a specific host.

IPv4 (Internet Protocol, version 4) An older version of IP that uses dotted-quad notation for IP addresses.

IPv6 (Internet Protocol, version 6) A newer version of IP that uses larger IP addresses and enhanced features.

ISO-8859 standard A series of standards that define standard 8-bit code pages for character encoding.

J–K

job In a Linux shell, a task running in the current terminal. Jobs can be started in the foreground as well as in the background. Every job is also visible as a process.

KDE A common desktop. See also desktop.

Kerberos A computer network authentication protocol that uses tickets to allow nodes and users communicating over an unsecure network to prove their identity. It provides mutual authentication and on Linux is used for authentication of users as well as services.

L

latency Any sort of delay in communication.

LDAP See Lightweight Directory Access Protocol (LDAP).

library A collection of reusable software components that can be used by multiple applications.

Lightweight Directory Access Protocol (LDAP) Originally, a protocol used to get information from an X.500 directory (which is a kind of address book). In modern computing environments, LDAP is also the service that provides centralized information that can be used for logging in and other purposes.

line printer remote An older network printing protocol optimized for less powerful printer hardware.

link A file, with its own inode, that points to another file.

Linux Unified Key Setup See LUKS (Linux Unified Key Setup).

load average The average CPU usage over a specific period of time.

locale In the context of internationalization and localization, the current language and country being used.

localization The process of displaying numbers, monetary values, dates, and times in a manner appropriate for the given country and language.

log rotation A service which ensures that log files cannot grow too big. Log files are monitored according to specific parameters, such as a maximum age or size. Once a specified parameter is reached, the log file closes, and a new log file is opened. Old log files are kept for a limited period and then are removed, often after only a couple weeks.

logging The process of submitting log entries to a service running on the system that notes those entries into a file or files or sends those entries across the network to another server that is configured to be a central logging repository.

logical extent The building block used in LVM to create logical volumes. It normally has a size of a few megabytes, which corresponds to the size of the physical extents that are used.

logical partition A partition created in an extended partition. See also extended partition.

logical volume (LV) The LVM component that represents a filesystem and that is composed of multiple physical extents.

logical volume manager (LVM) A Linux component that abstracts the layout of filesystems from the actual disks, allowing filesystems to be grown without needing to be contiguous.

LUKS (Linux Unified Key Setup) A disk encryption method commonly used on Linux systems.

LV See logical volume (LV).

M

MAC See mandatory access control (MAC).

mandatory access control (MAC) A system that makes use of security groups or domains to limit access to objects, such as files and directories.

mangle A firewall feature that modifies a network packet.

master boot record (MBR) On a BIOS system, the first 512 bytes on the primary hard disk. It contains a boot loader as well as a partition table that gives access to the different partitions on the hard disk of the computer. It is the first block on disk that is executed on boot to launch the boot manager.

MBR See master boot record (MBR).

merge In version control, to combine different versions of a file into a single result.

message of the day See MOTD (message of the day).

micro kernel A kernel in which modules are used to extend the basic kernel code.

module A piece of snap-in code. Modules are used by several systems on Linux, such as the kernel, GRUB2, and rsyslog. By using modules, Linux components can be extended easily, adding functionality without requiring a total rewrite of the software.

monolithic kernel A kernel in which all of the code is embedded within a single executable chunk of code.

MOTD (message of the day) A message that is displayed when a user logs in to a system.

mount point A directory on disk to which another filesystem is attached.

multifactor authentication A type of authentication in which a user is requested to provide multiple bits of evidence that prove the user’s identity.

N

name server In DNS, a server configured with a database that contains resource records used to answer DNS queries.

NAT (network address translation) In firewalling, a configuration in which a computer on a private network uses the public IP address of the router to connect to computers on the Internet; also referred to as masquerading. The computer on the Internet sees only the public IP address and therefore cannot connect directly to the computer on the private network. Masquerading makes it possible to share one public IP address between many computers and at the same time is a security feature.

network A grouping of hosts connected either by wireless signal or by cabling that can connect to each other and communicate in other ways.

Network File System (NFS) A common Unix solution to export physical filesystems to other hosts on the network. The other hosts can mount an exported NFS directory in their local filesystem.

network mask A dotted-quad notation used to define the network part of an IP address.

Network Time Protocol (NTP) A service that allows a computer to query time servers for the purpose of keeping accurate time.

NFS See Network File System (NFS).

NTP See Network Time Protocol (NTP).

numeric mode A method of setting object permissions that uses octal numbers.

O

octet A portion of an IPv4 address consisting of 8 bits, each with a value of 0 or 1.

OS (operating system) data Any data that is associated with the operation of an operating system.

OTP (One Time Password) A password that only permits access for a single instance.

OVA (Open Virtual Appliance) Effectively a bundling of one or more VMs together in an installable/runnable package such as a virtual appliance.

OVF (Open Virtualization Format) A compressed package file format that contains any needed certificates and disk image files and that is similar in format to a TAR archive file.

P

package manager A system such as APT or RPM that installs software and keeps track of what’s currently installed.

packet drop A process in which a remote system doesn’t respond to an inbound network packet.

page A page, memory page, or virtual page that is a fixed-length contiguous block of virtual memory, described by a single entry in the page table.

PAM (pluggable authentication module) A collection of libraries designed to provide an administrator with the means to change how user accounts are authenticated.

partition A subdivision of a hard disk on which a filesystem can be created to be mounted into the directory structure.

peripheral A device, such as a printer or a monitor, that connects to a computer.

permission trio A permission set for an object user owner, a group owner, and all other users.

physical extent A component of logical volume management that forms the basis of a logical volume. A physical volume, such as a disk, is split into blocks called physical extents.

physical volume (PV) The foundational building block of an LVM configuration that typically corresponds to a partition or a complete disk device.

PID See process identification number (PID).

pipe A structure that can be used to forward the output of one command to be used as input for another command.

pluggable authentication module See PAM (pluggable authentication module).

port A number associated with a service. The service listens for incoming network packets assigned to the port number.

Postfix A mail transfer agent, originally built by IBM, that is split into separate components to enhance security.

primary group The group owner of a file. Every Linux user is a member of a primary group.

primary partition In MBR, one of a maximum of four partitions that can be created in the master boot record. See also extended partition.

print queue A list of print jobs waiting to be printed.

print spooler The component responsible for taking the next job off the print queue and sending it to the printer.

priority In rsyslog, a level used to specify the severity of a logged event. Based on the severity, specific actions can be taken.

private key A key used to decrypt data that has been encrypted with a public key.

procedure In orchestration, the collection of steps that need to take place to complete an action.

process A task running on a Linux machine. A process roughly corresponds to a program, although one program can start multiple processes.

process identification number (PID) A unique number used to identify a process running on a Linux system.

public key A key provided to other users and hosts that is used to encrypt data. This data, when returned to the original host, can be decrypted by the private key.

Puppet An older and less capable method of providing configuration management that is being replaced by Chef.

PV See physical volume (PV).

Q–R

queue In process management, the list of processes waiting to be executed.

RADIUS (Remote Authentication Dial-In Service) A protocol that allows a client system to make use of a server to authenticate users.

RAID See redundant array of independent disks (RAID).

RCP See remote copy (RCP).

reboot To cause a system to go from a running or halted state to not running and then back to properly running again.

redirect To take content or output from a process and send that content or output to a file (either a device file or a regular file on disk).

redundant array of independent disks (RAID) A method of using regular disks to build a larger and more reliable set of disks, such as by mirroring writes to two separate disks.

relative path The location of a file, specified as an offset from the current working directory.

remote copy (RCP) A software program that allows users to copy files to and from a remote system. Unfortunately, this process sends data in plain text, making it an unsecure method.

repo See repository.

repository In version control, a storage area that keeps track of different versions of files. Also known as a repo.

Request for Comments (RFC) A publication that defines a standard, such as a protocol like IP.

RFC See Request for Comments (RFC).

root filesystem The filesystem that contains the root (/) directory.

router A device that transfers network packets from one network to another.

routing The process of sending network data from one Internet Protocol network to another via a gateway.

runlevel The services/daemons that will be running/stopped when the system is in a particular system state.

S

Samba The Linux service that implements the SMB protocol.

saturation A state in which throughput is often (or constantly) reaching the value of the bandwidth.

secondary group A group to which a user belongs but for which membership is not defined in the /etc/passwd file. When creating new files, the secondary group does not automatically become the owner of those files. Users can access files via permissions when using a secondary group.

Secure Shell (SSH) A solution that allows users to open a shell on a remote server, where security is implemented by using public/private key cryptography.

SELinux A security feature that involves using MAC (mandatory access control) to provide more secure access to files and directories.

SELinux Boolean A true/false value that can be used to configure an SELinux policy.

SELinux context Metadata applied to an object, such as a file, directory, or process. This metadata is used to determine how the rules of an SELinux policy will be enforced on the object.

SELinux policy Rules that determine how MAC is enforced on a system.

session The presence of a user on a system after being authenticated until logging out.

SetGID (SGID) A special permission set in which a command executes using the privileges of the group owner of the command.

SetUID (SUID) A special permission set in which a command executes using the privileges of the user owner of the command.

SGID See SetGID (SGID).

Shadow Suite A system function that allows for the encrypted passwords on a system to be kept in the much more secure /etc/shadow file instead of the less secure and often publicly available /etc/passwd file. Group passwords are also made more secure by being relocated from the public /etc/group file to the more secure /etc/gshadow file.

share A directory to which remote access is configured using a remote filesystem protocol such as NFS or CIFS.

shared object A library used by multiple applications and linked at runtime by the dynamic linker. Shared object files almost always end in .so.

shebang A pair of characters used in a script to indicate which shell should be used for executing the code in the shell script. If no shebang is used, the script code is interpreted by the parent shell, which may lead to errors in some cases. A shebang starts with a #, which is followed by a ! and the complete path name of the shell, such as #!/bin/bash.

shell metacharacters Characters such as *, ?, and [a-z] that allow users to refer to characters in filenames in a flexible way.

shut down To close down a system properly.

signal An instruction that can be sent to a process. Common signals exist, such as SIGTERM and SIGKILL, but the Linux kernel allows a total of 32 different signals to be used. To send a signal to a process, the kill command can be used.

Simple Mail Transfer Protocol (SMTP) A text-based protocol that allows different mail transfer agents to send mail between themselves.

Simple Network Management Protocol (SNMP) A protocol that allows for the management of network devices.

skel template A directory used to populate a new user account’s home directory with files.

slab A cache that holds objects that are located in memory and managed by a slab allocator; effectively a memory allocator for use by the kernel.

SMTP See Simple Mail Transfer Protocol (SMTP).

SNMP See Simple Network Management Protocol (SNMP).

source format A set of source files packaged up in an rpm or dpkg file that, when installed, populate a location and can be used to build a package from source.

source RPM A package containing source code and the instructions on how to build the source into a binary.

SQL See Structured Query Language (SQL).

SSH See Secure Shell (SSH).

standard error The default location to which a program sends error messages.

standard input The default location from which a program gets its input.

standard output The default location to which a program sends its regular output.

static linking The process of taking code from common libraries and making it a part of a runnable application rather than something brought in from a shared library.

sticky bit A special permission set that modifies the meaning of the write permission on a directory so that the only user who can delete a file in the directory is the file owner, the directory owner, or the root user. Historically, the sticky bit was used to keep a program resident in memory and prevent it from being swapped to disk.

strings A collection of characters, such as "hello", as opposed to a numeric type like an integer or a date.

Structured Query Language (SQL) A language used to query and manipulate relational databases.

subnetting The process of using a network mask to define the network part of an IP address.

SUID See SetUID (SUID).

swap space Hard drive space used in place of RAM when available RAM runs low.

symbolic mode A method of using symbols to set object permissions.

synchronization The process of producing an identical copy of a set of files from one location to another, typically for the purpose of backup or safekeeping. During this process, a comparison is made between the two locations, and the differences are copied from the source to the target, in varying levels of atomicity, such as file by file or byte by byte, depending on the parameters and options specified.

syslog A daemon that is the traditional logging service for Linux, recently supplanted in some instances by rsyslog and systemd logging.

system time The time maintained by the operating system. When a Linux system boots, system time is set to the current hardware time, and while the operating system is running, it is often synchronized using Network Time Protocol.

systemd The service manager on many distributions, which is the first process that starts after the kernel has loaded and takes care of starting all other processes and services on a Linux system.

T

table A type of firewall rule, such as filter, nat, or mangle.

TACACS+ (Terminal Access Controller Access-Control System Plus) A protocol that allows a client system to make use of a server to authenticate users.

tar command An archival tool that allows a user to create archives and to use compression utilities to additionally compress the contents of an archive.

target The action to be taken when a rule is matched.

TCP See Transmission Control Protocol (TCP).

TCP wrappers A library designed to allow the administrator the means to secure network-based services by using the /etc/hosts.allow and /etc/hosts.deny configuration files.

Telnet A software program that allows for connection to remote systems. Unfortunately, this connection is sent in plain text, making it an unsecure method.

throughput The amount of data that passes through media.

time synchronization A system which ensures that multiple servers are using exactly the same time. To accomplish time synchronization, it is common to use an external time server, as defined in the Network Time Protocol (NTP).

time zone A set of locations that share a common time, measured in an offset from Universal Coordinated Time.

timeout The use of a software component to determine whether a packet drop has occurred.

token A unique value (typically either a number or an alphanumeric value) that is generated by either a hardware device or a software program.

Transmission Control Protocol (TCP) A protocol that focuses on the transport of data packages. TCP differs from UDP in that the data packages are considered “reliable” because TCP performs error checking to make sure all data packages arrive at the destination.

two-factor authentication (2FA) A process in which a user must provide two different forms of identification to be authenticated.

U

UDP See User Datagram Protocol (UDP).

UFW (Uncomplicated Firewall) A front-end utility designed to make the process of configuring firewalls with iptables easier.

UID (user identification number) A unique number assigned to a user account.

ulimit A feature that allows an administrator to limit access to system resources for users and groups.

umask value A value applied to the default permissions for files and directories when creating a new file or directory. The umask value modifies the permissions placed on the new file or directory.

Unicode A universal encoding that defines each possible character as a code point (a unique number).

Universal Coordinated Time (UTC) A time standard that is globally the same, no matter which specific time zone a user is in. Universal Coordinated Time corresponds to Greenwich Mean Time.

Universal Serial Bus See USB (Universal Serial Bus).

UPG (user private group) A technique in which a new user is assigned to a private group that matches the user’s username.

Upstart The system used in RHEL 6 to start services during system initialization. It is similar in features to systemd and is an improvement over init.

USB (Universal Serial Bus) An industry standard for external devices.

User Datagram Protocol (UDP) A protocol that focuses on the transport of data packages. It is often contrasted with TCP, as they both perform similar functions. UDP differs from TCP in that the data packages are sent “connectionless,” so no error checking is performed.

UTC See Universal Coordinated Time (UTC).

UTF-8 A character encoding format that encodes all characters in a variable width using blocks of 8 bits. That is, characters are from 1 to 4 bytes long. UTF-8 is also backward compatible with 8-bit ASCII.

UTF-16 A character encoding format that encodes all characters in a variable width using blocks of 16 bits. That is, characters are either 2 or 4 bytes each.

V–Z

variable A label that corresponds to a location in memory that contains a specific value that can be changed dynamically. In scripting, variables are frequently used to allow the script to be flexible.

version control system Software that tracks changes to files over time and can be used to see history or revert to older versions of a file.

VG See volume group (VG).

virtual memory Hard drive space used in place of RAM.

virtualization The process of running a client operating system on a host as if it were running on hardware.

VM template A master version of a virtual machine that is used to make a copy that is then customized to become the VM that you want to spin up in your environment.

volume group A collection of physical volumes in a logical volume manager system. You can split up a volume group into logical volumes on which you make filesystems.

window A tmux or screen instance; a window is not necessarily a drawn window on the screen but may be a separate discrete instance of the BASH shell that contains a session.

Yellow Dog Updater (YUM) The meta package handler that on RHEL 7 is used to install packages from yum repositories.

Zypper The combination of ZYpp/libzypp and the zypper command, used to manage software mostly on SUSE systems and Ark.