Absolute path
A path that starts at the root directory, such as /etc/hosts, and does not depend on the current directory.
Glossary
Linux terms in plain English.
Short definitions for the words you will see across Linux documentation, command output, package managers, filesystems, boot logs, and troubleshooting guides.
A
APT
The high-level package manager used on Debian, Ubuntu, and related distributions.
B
Bootloader
Software started by firmware that loads the Linux kernel and passes it boot options.
Btrfs
A modern Linux filesystem with features such as checksums, snapshots, and subvolumes.
C
Command
A program, shell builtin, function, or alias invoked from a shell.
D
Daemon
A background process that provides a service, such as SSH, logging, printing, or a web server.
Desktop environment
A graphical user environment that includes a window manager, panels, settings, file manager, and desktop apps.
Distribution
A complete Linux operating system assembled from the kernel, tools, package repositories, installer, defaults, and documentation.
DNS
The naming system that translates hostnames such as example.com into IP addresses.
dpkg
The low-level Debian package tool used to query and install .deb package files.
E
EFI System Partition
A FAT-formatted partition used by UEFI firmware to store bootloader files.
Environment variable
A key-value string inherited by child processes, often used to configure command behavior.
ext4
A mature, common Linux filesystem used as a reliable general-purpose default.
F
Filesystem
The structure and rules used to store files and directories on a storage volume.
Firmware
Low-level software on hardware that initializes the machine and starts the boot process.
G
GNU
A free software project that provides many traditional user-space tools used on Linux systems.
GRUB
A widely used bootloader that can load Linux kernels and present boot menus.
H
Home directory
A user's personal directory, commonly /home/username, containing documents and user-specific configuration.
I
Initramfs
An early temporary user-space image used during boot to prepare and mount the real root filesystem.
K
Kernel
The core of the operating system that manages hardware, memory, processes, filesystems, and networking.
M
Mount point
A directory where a filesystem is attached into the Linux directory tree.
P
Package manager
A tool that installs, upgrades, removes, and queries software packages from repositories.
PATH
An environment variable listing directories the shell searches when you type a command name.
PID
A process ID, the numeric identifier Linux uses for a running process.
Pipe
A shell operator that sends the output of one command into the input of another command.
R
Repository
A signed collection of package metadata and packages used by a distribution's package manager.
Root directory
The top of the Linux filesystem tree, written as /.
Root user
The administrative superuser account with broad control over the system.
S
Shell
A command interpreter such as Bash or Zsh that reads commands and starts programs.
Socket
An endpoint for network or local interprocess communication.
sudo
A tool that lets permitted users run commands with elevated privileges according to policy.
systemd
A common Linux init system and service manager that starts units, tracks services, and integrates logging.
U
UEFI
Modern firmware interface that commonly starts bootloaders from an EFI System Partition.
User space
The part of the system where normal processes, shells, services, and applications run above the kernel.
V
Virtual filesystem
A filesystem-like interface generated by the kernel rather than stored as normal files on disk, such as /proc or /sys.
X
XFS
A high-performance Linux filesystem often used for large filesystems and server workloads.