Red Hat glossary
Key Red Hat certification terms and acronyms.
Definitions are AI-assisted and reviewed for general accuracy — verify critical details against Red Hat's official documentation.
ACLAccess Control List
An extended permission mechanism that allows fine-grained read, write, and execute rights to be assigned to specific users or groups beyond standard POSIX permissions.
Ad-hoc
A one-line Ansible command run directly from the CLI to execute a single module on managed hosts without writing a playbook.
Ansible
An agentless IT automation tool by Red Hat that uses SSH to configure systems, deploy applications, and orchestrate tasks via YAML-based playbooks.
ansible.cfg
The primary Ansible configuration file where settings such as inventory path, remote user, and privilege escalation are defined.
autofsAutomounter File System
A service that automatically mounts file systems on demand when accessed and unmounts them after a period of inactivity.
Block
A logical grouping of tasks in a playbook that allows shared directives, error handling via rescue, and cleanup via always.
chconChange Context
A command-line utility used to change the SELinux security context of a file or directory, effective until a relabel is performed.
Collection
A distribution format that bundles modules, plugins, roles, and playbooks into a single installable package identified by a namespace and name.
cron
A time-based job scheduler daemon that executes commands or scripts at specified intervals defined in crontab files.
DNFDandified YUM
The default package manager in RHEL 8 and later that installs, updates, and removes RPM packages while resolving dependencies automatically.
Facts
System information automatically gathered by Ansible from managed hosts at the start of a play, accessible as variables during execution.
firewalld
A dynamic firewall management daemon in RHEL that uses zones and services to manage iptables/nftables rules without requiring a full restart.
FQCNFully Qualified Collection Name
The complete namespace.collection.module reference format used to unambiguously identify Ansible modules and plugins from collections.
fstabFile Systems Table
A system configuration file at '/etc/fstab' that defines how disk partitions and remote file systems are mounted automatically at boot.
GalaxyAnsible Galaxy
A public repository and CLI tool for finding, sharing, and installing community-contributed Ansible roles and collections.
group_vars
A directory or file structure used to assign variables to all hosts within a specific inventory group.
GRUB2Grand Unified Bootloader version 2
The default bootloader for RHEL systems that loads the kernel and initramfs, and can be modified to pass kernel parameters at boot.
Handler
A task that runs only when notified by another task, typically used to restart services after a configuration change.
host_vars
A directory or file structure used to assign variables to specific hosts, overriding group or default variable values.
Idempotency
The property of Ansible tasks whereby running the same task multiple times produces the same end state without unintended side effects.
Inventory
A file or directory listing managed hosts and groups that Ansible targets during automation runs; can be static or dynamic.
Jinja2
A Python-based templating language used in Ansible to dynamically generate configuration files and evaluate expressions within playbooks.
journald
A systemd component that collects and stores binary log data from the kernel, services, and applications, queryable via journalctl.
Loop
A playbook directive that iterates a task over a list of items, reducing repetitive task definitions within a play.
LVMLogical Volume Manager
A device-mapper framework that abstracts physical storage into volume groups and logical volumes, enabling flexible disk management and resizing.
Module
A discrete, reusable unit of code that Ansible executes on managed hosts to perform specific actions such as file management or package installation.
NFSNetwork File System
A distributed file system protocol that allows a client to mount and access directories shared by a remote server over a network.
Playbook
A YAML file containing one or more plays that map hosts to tasks, defining the desired state of managed nodes.
Privilege Escalation
The mechanism in Ansible (via become) that allows tasks to run as a different user, typically root, on managed hosts.
PVPhysical Volume
A disk or partition initialized for use by LVM, serving as the lowest-level storage building block in the LVM hierarchy.
RHELRed Hat Enterprise Linux
A commercially supported Linux distribution by Red Hat designed for enterprise servers, and the target platform for the RHCSA exam.
Role
A structured directory layout that bundles tasks, handlers, variables, templates, and files into a reusable, shareable automation unit.
RPMRed Hat Package Manager
A package management system and file format used to install, query, verify, and remove software packages on RHEL-based systems.
SELinuxSecurity-Enhanced Linux
A Linux kernel security module that enforces mandatory access control policies to confine processes and limit damage from compromised services.
SSHSecure Shell
A cryptographic network protocol used for secure remote login, command execution, and file transfer between hosts.
stratis
A local storage management solution in RHEL that simplifies creating and managing pools and file systems with thin provisioning.
sudoers
A configuration file at '/etc/sudoers' that defines which users or groups may run commands with elevated privileges using the sudo command.
swap
A designated disk area used to extend virtual memory by paging inactive memory pages out of RAM when physical memory is exhausted.
systemd
The init system and service manager used in RHEL that manages system boot, services, targets, and dependencies via unit files.
Tags
Labels applied to tasks or plays allowing selective execution of only tagged portions of a playbook at runtime.
target
A systemd unit type that groups other units to define system states, replacing SysV runlevels (e.g., multi-user.target, graphical.target).
Task
A single unit of work in a playbook that calls an Ansible module with specific arguments to perform an action on managed hosts.
Template
A Jinja2-based file used with the template module to generate dynamic configuration files deployed to managed hosts.
tuned
A system tuning daemon in RHEL that applies pre-defined performance profiles to optimize kernel parameters for specific workloads.
umaskUser file-creation mode mask
A value that determines the default permissions subtracted from the maximum when new files and directories are created.
Variable
A named placeholder in Ansible used to store dynamic values that can be reused across tasks, templates, and conditionals.
VaultAnsible Vault
An Ansible feature that encrypts sensitive data such as passwords and keys within playbooks or variable files using AES256 encryption.
VDOVirtual Data Optimizer
A RHEL storage layer that provides inline deduplication and compression to reduce physical disk usage for block devices.
VGVolume Group
An LVM construct that pools one or more physical volumes into a single storage unit from which logical volumes are allocated.
When
A conditional directive in Ansible tasks that restricts task execution to hosts or situations matching a specified Jinja2 expression.