To restrict SSH access to specific users, you would modify the /etc/ssh/sshd_config file. This file contains the configuration options for the SSH server, including settings related to user access, authentication, and permissions.

The primary keyword to start a loop that will iterate a fixed number of times in shell scripting is for. The for loop allows you to specify the number of iterations and is commonly used for such purposes.

The command 'lsmod' is used to list currently loaded kernel modules in Linux. This command displays a list of all the kernel modules that are currently loaded into the running kernel.

The while loop in shell scripting tests the condition before executing the body of the loop. It will repeatedly execute the loop body as long as the specified condition remains true.

In Linux, services that are set to restart automatically after a failure are said to be "Autorestart." This feature ensures that critical services can recover from failures and continue running, enhancing system reliability and availability.

In Linux, the visudo command is used to see who has been granted sudo access. This command opens the sudoers file in a safe manner for editing and displays the sudo configuration. It's important to use visudo to avoid syntax errors in the sudoers file, which could lock you out of administrative access.

systemd is the system in Linux that allows for the management and supervision of service daemons. It's a modern initialization system and service manager that replaces the traditional SysV init. systemd provides enhanced control and monitoring of services and system initialization.

The correct option is snapshot. Btrfs, a modern file system for Linux, provides a feature that allows for creating a readable/writable "snapshot" of a subvolume. Snapshots are a powerful tool for data protection and efficient use of disk space.

In Linux, the jobs command is used to display the status of jobs in the current session. It provides information about background processes or jobs started within the current shell session.

The ip command in Linux can be used to manipulate or display IP routing tables. It's a powerful and versatile tool for configuring network interfaces, routes, tunnels, and more. Unlike older commands like route and ifconfig, ip is considered a modern and more comprehensive replacement.