Linux

A quick fight game made in bash

#!/bin/bash
health=10
enemy=10
while [[ $health > 0 && $enemy > 0 ]]
do
	echo You: $health
	echo Enemy: $enemy
	input=
	while [[ $input != 0 && $input != 1 ]]
	do
		echo "Pick a number (0-1)"
		read input
		if [[ $input != 0 && $input != 1 ]]; then
		       echo "Wrong input"
		fi	       
	done
	hit=$(( $RANDOM % 2 ))
	if [[ $input == $hit ]]; then
		((enemy--))
	else
		((health--))
	fi
done
if [[ $health == 0 ]]; then
	echo "You Died"
else
	echo "You defeated the beast"
fi

Save this as a file named fight.sh onto any linux system, chmod +x it, run it and have fun

Find manually installed packages that has other packages depending on it on Debian based systems

Running command below generates a list of packages that can be marked as automatically installed, as long as apt-rdepends package were already installed. It generates a script that can be used to mark all found packages as manually installed.

echo \#\!/bin/bash > mark-auto.sh; apt-mark showmanual|xargs -I{} sh -c '[ "{}" = "$(apt-rdepends -r --state-follow=Installed --state-show=Installed {} 2>/dev/null)" ] || echo apt-mark auto {}' >> mark-auto.sh

It can be modified to mark packages automatically if preferred instead of writing to a script

apt-mark showmanual|xargs -I{} sh -c '[ "{}" = "$(apt-rdepends -r --state-follow=Installed --state-show=Installed {} 2>/dev/null)" ] || apt-mark auto {}'

Before running apt-get autoremove run it with pretend mode (-s), e.g

apt-get -s autoremove --purge

Mark any package not desired to be removed with

apt-mark manual <package>

Installed Ubuntu 22.04 LTS from scratch, to be released within a week (April 21, 2022)

Ubuntu 22.04 LTS is soon to be released so I decided to do a complete reinstall. After booting into Linux Live USB first I've deleted everything from my old install except for the important stuff I needed to keep. Then I've reinstalled the base system using debootstrap and used a script I made to enter the chroot, I installed required packages there to make it boot and to be able to access network. Finally I've installed everything else I needed including graphical interface where a list of installed previously packages would help alot. Such list could be generated by running commands as shown in example below.

First generate package list files while in old system as shown below

$ apt-mark showmanual > manual_old.txt
$ dpkg-query -Wf '${Package}\n' > packages_old.txt

After reinstalling system repeat same in the new installation, only change output file names where needed.

$ apt-mark showmanual > manual.txt
$ dpkg-query -Wf '${Package}\n' > packages.txt

Finally compare package list files generated above, a list of missing packages would be stored in files as shown below

$ sort manual_old.txt > 1.txt; sort manual.txt > 2.txt; comm -23 1.txt 2.txt > missing_manual.txt
$ sort packages_old.txt > 1.txt; sort packages.txt > 2.txt; comm -23 1.txt 2.txt > missing.txt

Spam generator

$ for q in $(eval echo {1..$((2+$RANDOM%200))}); do echo $(cat </dev/urandom|tr -cd '[:lower:]'|tr -s '[:print:]'|head -c $((2+$RANDOM%32))); done|xargs

Generates a random amount of random words containing random lowercase letters (up to 200 words and 32 letters per word)

Double dollar sign ($$) in bash

It substitutes to PID of the current running shell. For example running

ps -Alf|grep $$

generates interesting results, as shown below

$ ps -Alf|grep $$
0 S juozas     11125   11120  0  80   0 -  3391 do_wai 22:43 pts/0    00:00:00 bash
4 R juozas     11197   11125  0  80   0 -  3506 -      22:46 pts/0    00:00:00 ps -Alf
0 S juozas     11198   11125  0  80   0 -  2859 pipe_w 22:46 pts/0    00:00:00 grep --color=auto 11125

Another example is to use it in the file names where it gets substituted with the PID of the current running shell.

$ cat >f$$.txt <<EOF
This is a test. The pid of running shell is $$
EOF
$ cat f$$.txt
This is a test. The pid of running shell is 11125
$ ls f$$.txt
f11125.txt
$ LC_ALL=C rm -v f$$.txt
removed 'f11125.txt'

ffmpeg /dev/urandom test video 4 (mkv, low resolution)

from https://www.youtube.com/watch?v=jFqGCiQyH9Q

Generate 1280x720 image with 16x9 grid containing random colors in each cell

$ dd if=/dev/urandom bs=1 count=432 of=in.bin

$ convert -depth 8 -size 16x9 rgb:in.bin -scale 1280x out.png

Open random page of kyselo right from unix terminal

$ BEGIN=$(($(date -d '2020-07-13T00:35:49' +"%s"))) END=$(date +"%s"); firefox https://kyselo.eu/all?since=$(date -d @$(shuf -i $BEGIN-$END -n 1) +"%Y-%m-%dT%H%%3A%M%%3A%S")

Non native theme of the widgets on Mozilla Firefox looks ugly while using Linux. It can be disabled on about:config page.

from https://thumbsnap.com/i/5xRTA8Ny.png

Me trying to compile some programs on Gentoo

from https://www.youtube.com/watch?v=XWMDjDXTuds

from https://loforo.com/asset/14434/2457_f7ce.gif

from http://soup.nowhereman.de/assets/3094/4865_ca0b.jpeg

from http://soup.nowhereman.de/assets/13230/8967_6b75.jpeg

Gentoo installation in virtualbox is never w/o bugs...
Triggered by running

# emerge --ask --verbose --update --deep --newuse @world