A vulnerability in Apache Log4j, a widely used logging package for Java has been found. The vulnerability, which can allow an attacker to execute arbitrary code by sending crafted log messages, has been identified as CVE-2021-44228 and given the name Log4Shell. It was first reported privately to Apache on November 24 and was patched with version 2.15.0 of Log4j on December 9. It affects Apache Struts, Apache Solr, Apache Druid, Elasticsearch, Apache Dubbo, and VMware vCenter. Since then, it has been disclosed that in certain non-default conditions, the original patch was incomplete; this was designated as CVE-2021-45046 and a new version of Log4j, 2.16.0, has been released.

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Run sudo /usr/bin/nvidia-uninstall to uninstall a manually installed driver, if you still got one.

Remove everything of your old NVIDIA driver (simulate first):

<code>sudo apt remove --purge -s nvidia-*
sudo apt remove --purge -s libnvidia-*

If only nvidia packages are there to be removed, remove really:

<code>sudo apt remove --purge nvidia-*
sudo apt remove --purge libnvidia-*

Run sudo apt update and ubuntu-drivers devices again.

If nvidia-390 is still recommended, add your output of sudo ubuntu-drivers autoinstall again.

The original installation of zpool was from a POPOS 20 install. After Installing a new Ubuntu system over the top of POPOS, the zpool was not listed. Here are the steps to restore the zpool.

Install zfsutils

# apt install zfsutils-linux

When trying to import, I received an error:

# zpool import
   pool: myzpool
     id: 13464327419314907931
  state: ONLINE
status: The pool was last accessed by another system.
 action: The pool can be imported using its name or numeric identifier and
	the '-f' flag.
   see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-EY

	myzpool                                         ONLINE
	  mirror-0                                      ONLINE
root@skynet:/home/rogerp# zpool import myzpool
cannot import 'myzpool': pool was previously in use from another system.
Last accessed by pop-os (hostid=b5f0b0a0) at Tue May  4 04:27:02 2021
The pool can be imported, use 'zpool import -f' to import the pool.

Import using the -f flag and the pool name that was created originally.

# zpool import -f myzpool



How to mount a NTFS disk in Debian.

Find the disk:

# fdisk -l
Disk /dev/sda: 232.9 GiB, 250059350016 bytes, 488397168 sectors
Disk model: ST3250310AS
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x84c02518

Device     Boot     Start       End   Sectors  Size Id Type
/dev/sda1  *         2048 471801855 471799808  225G 83 Linux
/dev/sda2       471803902 488396799  16592898  7.9G  5 Extended
/dev/sda5       471803904 488396799  16592896  7.9G 82 Linux swap / Solaris

Disk /dev/sdb: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: WDC WD10EZRX-00L
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x93665d93

Device     Boot Start        End    Sectors   Size Id Type
/dev/sdb1        2048 1953521663 1953519616 931.5G  7 HPFS/NTFS/exFAT

So, the NTFS is disk sdb1. Find the UUID value.

 sudo blkid  /dev/sdb1
/dev/sdb1: LABEL="Backup" UUID="0CF88F39F88F2056" TYPE="ntfs" PTTYPE="atari" PARTUUID="93665d93-01"

Install NTSF-3G:

# sudo apt-get install ntfs-3g

Create the /mnt/ntfs/ directory

# sudo mkdir -p /mnt/ntfs/

Add to fstab.

# nano /etc/fstab
# UUID="YOUR-UID-HERE" /mnt/ntfs/ ntfs-3g rw,uid=1000,gid=1000,dmask=0002,fmask=0003 0 0
UUID="0CF88F39F88F2056" /mnt/ntfs/ ntfs-3g rw,uid=1000,gid=1000,dmask=0002,fmask=0003 0 0

Test it

# sudo mount -a
# df -h
/dev/sdb1       932G  295G  638G  32% /mnt/ntfs
# cd /mnt/ntfs/
# ls -l


For CentOS, the DIG tool is a part of the BIND Utilities so you need to install them.

# yum whatprovides '*bin/dig'

To install the BIND Utilities, type the following:

# yum install bind-utils


Update Debian

 $ sudo apt update

Install dnsutils package with the following command:

$ sudo apt install dnsutils -y

Check dig

dig -v
DiG 9.11.5-P4-5.1+deb10u5-Debian

To find out where disk space is being used:

Get to the root of your machine by running

# cd /


# sudo du -h --max-depth=1

Note which directories are using a lot of disk space.
cd into one of the big directories.

# ls -l

to see which files are using a lot of space. Delete any you don’t need.
Repeat steps to run once you cd into the directory with the largest size

sudo du -h --max-depth=1