This file prevents any non-root user from logging in to the system, regardless of the authentication method. The contents of the file are displayed to the user before the login is terminated. This can be useful for system maintenance or security reasons.

The setfacl -m u:Oliver:rwx /cloud_users command modifies the ACL (Access Control List) for the directory cloud_users, granting the user Oliver read, write, and execute permissions. This is the correct syntax for assigning specific permissions to a user.

The slowness is caused by the CPU being overloaded. The iostat command shows that the CPU utilization is
100%, which means that there are more processes competing for CPU time than the CPU can handle. The other options are incorrect because:
* The system is not running out of swap space, as shown by the iostat command, which shows that there is no swap activity (si and so columns are zero).
* The memory is not exhausted, as shown by the free -m command, which shows that there is still available memory (avail column) and free buffer/cache memory (buff/cache column).
* The processes are not paging, as shown by the vmstat command, which shows that there are no major page faults (majflt column) and no swap activity (si and so columns). References: CompTIA Linux+ Study Guide, Fourth Edition, page 417-419, 424-425.

The error given is what the user sees when the immutable flag has been set on a file. Therefore
'chattr -i test.txt' will remove the immutable flag (remember that chattr uses - and + to turn off/on options unlike a normal command option which is only ever preceeded by a -) so that the file can then be deleted by rm.

"modify the /etc/fstab text file to automatically mount the new partition by opening it in an editor and adding the following line:
/dev/ xxx 1 /data ext4 defaults 1 2
where xxx is the device name of the storage device"
https://learning.oreilly.com/library/view/mastering-linux-system/9781119794455/b01.xhtml