cyber

Linux-based operating system

An operating system built on Linux, commonly used for servers, cloud systems, networking devices, and other systems that need flexibility and strong administration tools.

File system

The organized collection of files and directories stored on a computer.

File

A named collection of data. In Linux, many system resources, including directories, are treated as files.

Directory

A special type of file that organizes and contains other files and directories.

Home directory

The personal directory assigned to a Linux user, commonly represented by a tilde (~).

Shell

A program that lets a user interact with the operating system by entering commands.

Command line

A text-based interface where a user enters commands for the operating system to execute.

Path

The location of a file or directory within the file-system hierarchy.

Current working directory

The directory in which the shell is currently operating.

Relative path

A path written in relation to the current working directory, such as ../Pictures.

ls

Lists the contents of a directory.

cd

Changes the current working directory.

pwd

Prints the full path of the current working directory.

cat

Displays the contents of a file in the terminal.

mkdir

Creates a new directory.

mv

Moves or renames a file or directory.

touch

Creates an empty file or updates a file's timestamp.

cp

Copies a file while leaving the original in place.

rm

Removes a file.

rmdir

Removes an empty directory.

Access control

The management of who or what may access a resource and what actions they are allowed to perform.

Owner

The user account that owns a Linux file or directory.

Group

A collection of users that can be assigned shared access to a Linux file or directory.

Other

The permission category for users who are neither the owner nor members of the assigned group.

Read permission

Represented by r; allows a user to read a file or view a directory's contents.

Write permission

Represented by w; allows a user to modify a file or change a directory's contents.

Execute permission

Represented by x; allows a user to run a file or enter a directory.

Permission matrix

Linux notation identifying an item's type and the read, write, and execute permissions for owner, group, and other.

Long listing

Detailed ls output (ls -l) showing permissions, ownership, size, timestamp, and filename.

File type

The actual format or kind of data in a file; in Linux it is not determined only by the filename extension.

file command

Examines a file and reports its actual type.

Wildcard

A character such as * that stands for multiple possible filenames or other text when a command is interpreted.

Hidden file (dot file)

A Linux file whose name begins with a period, so ordinary ls output hides it.

Encryption

Transforming readable information so that it requires the correct key or passphrase to read.

gpg

GNU Privacy Guard; an open-source tool used to encrypt and decrypt data with different encryption algorithms.

Passphrase

A secret phrase used to protect encrypted data and authorize decryption.