The sleep command is used in a shell script to introduce a delay. You specify the number of seconds to pause the script's execution. It's commonly used for debugging to observe intermediate results or to add pauses for various purposes.

To execute a script in Bash, you often need to make it executable by running chmod +x script_name, and then you use the ./ symbol before the script name to specify the current directory. This tells the shell to execute the script from the current directory.

The command "crontab -l" is used to view the list of scheduled tasks (cron jobs) for the system. It lists the cron entries for the currently logged-in user. Scheduled tasks are used to automate various processes at specific times or intervals in a Linux system.

To restrict users from logging in via SSH, you would modify the /etc/ssh/sshd_config file. This file contains configuration options for the SSH server, and you can specify access restrictions and settings here.

SELinux (Security-Enhanced Linux) enforces mandatory access controls at the kernel level in Linux. It provides a powerful and flexible security framework that allows administrators to define fine-grained access policies for processes, files, and resources on a system.

The Arch distribution is known for its advanced package management system called "pacman." Arch Linux uses a rolling release model and the pacman package manager for installing, updating, and managing software packages.

The primary protocol used by NFS (Network File System) for sharing files is NFS itself. NFS is a network protocol specifically designed for sharing files and directories among networked computers. It is commonly used in Unix and Linux environments.

To ensure a consistent policy across machines, SELinux policies can be stored in Text format. The SELinux policy language is human-readable and editable in text format, making it easier to understand and manage security policies.

SELinux operates under two primary modes: Enforcing and Permissive. In Enforcing mode, SELinux actively enforces security policies and denies any actions that violate these policies. In Permissive mode, SELinux logs policy violations but doesn't actively deny them, making it a useful mode for policy debugging.

The file that defines the default settings when a new user account is created in Linux is /etc/login.defs. This file contains various parameters and settings related to user account creation, password policies, and more. Modifying this file can affect the behavior of the useradd and adduser commands.