You could also do 
<code>
chown -R username:groupname .
</code>
, which would change the permissions on the current directory, and then recurse down inside of it and all subfolders to change the permissions.

<code>
chmod -R 666 /var/www
</code>
will give read, write permissions for everyone.

Partitions:
<code>
lsblk -f 
</code>
or:
<code>
# file -sL /dev/sd*
</code>
result:
<code>
/dev/sda1: Linux rev 1.0 ext4 filesystem data, UUID=63fa0104-4aab-4dc8-a50d-e2c1bf0fb188 (extents) (large files) (huge files)
/dev/sdb1: Linux rev 1.0 ext2 filesystem data, UUID=b3c82023-78e1-4ad4-b6e0-62355b272166
/dev/sdb2: Linux/i386 swap file (new style), version 1 (4K pages), size 4194303 pages, no label, UUID=3f64308c-19db-4da5-a9a0-db4d7defb80f
</code>
Check ext2 ,ext3, ext4 partition:
<code>
sudo umount /dev/sdXN
sudo e2fsck -f -n /dev/sdXN
</code>
-n reports issues without making changes. If you want e2fsck to repair errors interactively, rerun without -n:
<code>
sudo e2fsck -f /dev/sdXN
</code>

Pack:
<code>
tar czf name_of_archive_file.tar.gz name_of_directory_to_tar
</code>

Unpack:
<code>
tar -xzvf file.tar.gz
</code>

[[https://linuxize.com/post/how-to-use-scp-command-to-securely-transfer-files/|SCP]]:
<code>
scp [OPTION] [user@]SRC_HOST:]file1 [user@]DEST_HOST:]file2
</code>

Rsync to NTFS filesystem (rsync have to be installed on boths machines)
<code>
rsync -rtv --modify-window=1 [user@]SRC_HOST:]file1 [user@]DEST_HOST:]file2
</code>

Password less SSH
http://www.linuxproblem.org/art_9.html
<code>
cat .ssh/id_ed25519.pub | ssh b@B 'cat >> .ssh/authorized_keys'
</code>

[[https://www.stationx.net/how-to-use-nmap-to-scan-a-network/|Scan network]]:
<code>
sudo nmap -sn 192.168.0.0/24
</code>

https://reintech.io/blog/setting-up-nfs-server-on-debian-12

Add PPA Debian:
<code>
sudo apt -y install software-properties-common python3-launchpadlib
</code>

Hex Editors for Linux
<code>
sudo apt install hexedit
</code>