Linux Variables and Commands

EUID

• The current user's ID number.

• The user's email address.

• The user's password.

• The user's session token.

MAIL

• The path to the current user's mailbox file.

• The location of the user's email server.

• The default email application on the user's device.

• The settings for the user's email account.

Shell variable

• A Linux variable that is not inherited by child shells and processes.

• A global variable accessible by all processes.

• A variable that stores user preferences in Linux.

• A temporary variable used for session management.

BASHOPTS

• The list of options that were used when Bash was executed.

• A command to display the current directory in Bash.

• A variable that stores the last executed command in Bash.

• A function to list all available Bash commands.

User variable

• A variable that is defined in the system's environment settings.

• A Linux shell variable that is typically defined at the shell prompt or added when scripts that are defined in a user's profile are run.

• A variable that is only accessible within a specific function or block of code.

• A variable that is automatically generated by the operating system.

HOME

• The absolute path of the user's home directory.

• The location where system files are stored.

• A temporary directory for storing files.

• The directory containing all user applications.

HISTFILE

• The filename where past commands are stored.

• A command to clear the terminal history.

• A file that stores system logs.

• The name of the current user session.

HISTSIZE

• The maximum number of files that can be opened in a session.

• The number of lines or commands that are stored in a history list while your shell session is ongoing.

• The total size of the shell's memory allocation.

• The number of processes that can run simultaneously in the shell.

PS1

• The characters that the shell uses to define what the shell prompt looks like.

• A command used to list files in a directory.

• A variable that stores the current user's home directory.

• A function that executes a script in the background.

LANG

• The language the operating system uses.

• A programming language for web development.

• A markup language for structuring documents.

• A scripting language for automating tasks.