The vim-gnupg plugin lets vim edit gpg-encrypted files as if they were unencrypted.

It's probably in your package manager. If not, you'll need to endure the faff of following the instructions.

Making keys

Generate keys:

1gpg --full-generate-key

Follow the guide.

Encrypting a file

1gpg -r malinfreeborn@posteo.net -e file

-r specifies the recipient.

Check you have an encrypted version of your file.

Changing Expiration Dates

1gpg --list-keys
2# or...
3gpg -k

... and then use the second part of 'pub', which is …

Basic Documents

Great a file called name.ms, with the following content:

1.TL
2Groff-Time
3.AU
4Ghost
5.NH
6How to Format Groff Documents.
7.PP
8Groff needs two new lines to show a new paragraph.

Then make a pdf from the document with:

groff -ems name.ms -Tpdf > name.pdf

The commands must be placed at the start of a …

Convert jpg to png.

1convert image.jpg image.png

1convert image.jpg -quality 50 image.jpg

'Quality' must be from 1 to 100.

1convert -resize 50% image.jpg image2.jpg

Resizing only changes jpegs. Change a png with:

1convert input.png png8:out.png

Invert Colours

1convert input.jpg output.jpg -negate

Make Images Smaller

1 …

Intro

This is a basic Linux firewall program.

Look at your firewalls:

1iptables -L

We see the output of input, output and forwarding rules.

Forward

I don't need any forwarding, so I'm going to drop all forwarding:

1iptables -P FORWARD DROP

Input

Let's 'A'dd, or 'A'ppend a rule with -A. Let's drop all input from a …

See a running log of all system messages:

1journalctl -f

Or just one user:

1journalctl --user -f

Or just one unit (sshd):

1journalctl -f -u sshd

Find errors since November

1journalctl --since=2018-11-01 --grep="EXT4-fs error"

Limit size to 2G.

1journalctl --vacuum-size=2G

Log the fact that you've installed your …

Living Space

Kernel modules live in lib/modules/$(uname -r)

Change

Load them with

1sudo modprobe ath9k

Or remove one with

1sudo modprove uvcvideo

The PC's irritating speaker beep can be really annoying. Disable it with:

1sudo modprobe -r pcspeaker

Permanently disable a module by blacklisting it in /etc/modprobe.d:

1 …

Check which kernet modules are loaded into memory

1sudo /sbin/lsmod 

Check which virtual box modules are loaded into memory

1sudo /sbin/lsmod | grep vbox 

Virtual box is using vboxpci, vboxnetadp, vboxnetflt, vboxdr.

Look at what's claiming wifi:

1sudo lshw -C network

If this shows that the device is 'unclaimed' then …

Set Layout with X Display

Set layout to British English.

1setxkbmap -layout gb

Or Polish with:

1setxkbmap -layout pl

Set 'alt + shift', as the command which cycles …

Get the basic config:

1mkdir ~/.config/khard

1cp /usr/share/doc/khard/examples/khard/khard.conf.example ~/.config/khard.conf

Short list

1khard list

Longer list

1khard show

Show from addressbook 'work'

1khard list -a work

Make a new contact in address book 'family'

1khard new -a family

1khard edit grampa

1khard remove …