Below you will find alphabetically sorted list of commands and definitions of terms used in Linux or open source.
Alphabetically sorted Definitions of Terms
Below definitions of terms are some of the most commonly used terms in Linux command line.
A
- Absolute Path: Specifies the complete path to a file or directory from the root directory (/). It always starts with a slash. For example, /home/user/documents.
- Alias: A shortcut or substitute name for one or more commands. Aliases allow users to create simple names for long and complex commands. For example, alias ll=‘ls -l’ creates an alias ll for the command ls -l.
- Argument: An input provided to a command that specifies data for the command to process. Arguments often include filenames or options that modify the command’s behavior.
B
- Background Process: A process that runs independently of the user’s direct interaction. It allows the user to continue using the shell while the process executes. Initiated by adding & at the end of a command.
C
- Command Line Interface (CLI): A text-based interface where the user interacts with the computer’s operating system by typing commands.
- Cron: A time-based job scheduler in Unix-like systems that executes commands or scripts at specified times and dates. It is used for automating recurring tasks.
- Current Working Directory: The directory in which a user is currently operating. Commands without specified paths act relative to this directory. Use pwd to display it.
D
- Daemon: A background process that runs continuously and performs specific operations or awaits certain conditions. Commonly used for services like web servers.
- Directory: A location in the file system used to store files and other directories. Directories help organize files in a hierarchical structure.
E
- Environment Variable: A dynamic value that can affect the way running processes behave on a computer. Examples include PATH, HOME, and LANG.
- Executable: A file that can be run as a program or command. In Linux, a file must have execute permissions to be considered executable.
F
- File Permissions: Rules that define who can read, write, or execute a file or directory. Permissions are assigned to user, group, and others.
- Filesystem: The method and data structure that the operating system uses to control how data is stored and retrieved. Examples include ext4, NTFS, and FAT32.
- Foreground Process: A process that occupies the terminal for user input and output. The shell waits for the process to complete before returning to the command prompt.
G
- Glob: A pattern used to match filenames with wildcard characters like *, ?, and []. Also known as wildcard patterns.
- GNU: A recursive acronym for “GNU’s Not Unix!”, representing a free software movement that provides a collection of software for Unix-like operating systems.
H
- Home Directory: The personal directory assigned to a user account for storing files and personal settings. Typically located at /home/username.
- Hostname: The unique name assigned to a computer on a network. It is used to identify the device in communications over a network.
I
- Inode: A data structure in a Unix-style file system that stores information about a file or directory, excluding its name or actual data.
J
- Job: A task or command that has been initiated by the user. Jobs can run in the foreground or background and are managed using job control commands.
K
- Kernel: The core component of the operating system, responsible for managing system resources, hardware communication, and system calls.
L
- Link: A pointer or reference to a file or directory. There are two types: hard links and symbolic (soft) links.
M
- Man Page: Short for manual page, it is documentation that provides detailed information about commands and programs. Accessed using the man command.
- Mount: The process of making a file system accessible at a certain point in the directory tree. The mount command attaches a file system to a specified directory.
- Multiuser: A system that allows multiple users to access and use computing resources simultaneously.
N
- Network Interface: A software or hardware interface between two systems communicating over a network.
O
- Open Source: Software with source code that anyone can inspect, modify, and enhance.
P
- Path: A string that represents the location of a file or directory in the file system. It can be absolute or relative.
- Pipeline: A sequence of one or more commands separated by the pipe character |, where the output of one command serves as the input to the next.
- Process: An executing instance of a program. Each process is assigned a unique process identifier (PID).
R
- Regular Expression: A sequence of characters that defines a search pattern, mainly used for pattern matching with strings.
- Relative Path: A file or directory location relative to the current working directory, does not begin with /.
S
- Script: A file containing a sequence of commands that are executed by the shell interpreter.
- Shell: A program that provides the command line interface for users to interact with the operating system.
T
- Terminal: An application that provides a text-based interface to the shell. Users enter commands via the terminal.
- Text Editor: A program used for editing plain text files. Examples include nano, vim, and gedit.
U
- User: An individual who uses the computer system. Each user has a unique username and home directory.
- User Permissions: The access rights granted to a user, determining what actions they can perform on files and directories.
V
- Variable: A named object that contains data used by one or more programs. Environment variables are a type of variable used by the shell and applications.
W
- Wildcard: Symbols used to represent one or more characters in filenames or commands. Common wildcards include * (matches any number of characters) and ? (matches any single character).
X
- X11/X Window System: A windowing system for bitmap displays on UNIX-like operating systems, providing the basic framework for a GUI environment.
Z
- Zombie Process: A process that has completed execution but still has an entry in the process table, typically waiting for its parent process to read its exit status.
This Annexure has alphabetically sorted definitions of Terms used in Linux command line. This list was compiled from variety of public domain sources, and sorting was done using Mistral LeChat, a LLM.
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