golb

Linux utils

Learn multiplications

for i in {5..7}; do  for e in {5..7}; do echo "$i*$e=$(bc<<<$i*$e)" | spd-say -e ;sleep 2; done; done

Get sound update

watch -n 10 'mycommand && spd-say done || echo "no"'

Change partition

# list partitions
fdisk -l

fdisk /dev/sdx

# touch d for delete partition

# touch n for new partition

Format partition

mkfs.vfat /dev/sdx1

Use dd to copy an ISO

dd if=file.iso of=/dev/sdx bs=1M status=progress

Caption:

Copy file to clipboard

xclip -sel c < input_file

Reference: https://stackoverflow.com/a/62168635

Show listening ports

ss -ptulwn | grep LISTEN

Change the pager

Change the pager of man :

export PAGER=less

Download urls

cat a | while read f; do curl -L -b 'cookie=value' -O -J "${f}"; done

iftop

# display bandwidth usage on an interface by host
# as root
iftop -s wlp0
# change to your interface

slock

# lock your screen
slock

aspell

aspell -l en -c file.txt

Utils

# IPv4 addresses:
cat /proc/net/fib_trie

# hex-encoded port data:
cat /proc/net/tcp

Using su on Linux (Debian)

The su command allows you to switch users for the duration of a session (after entering the password, if there is one). To use it, type:

su USERNAME

You can also use it to become root simply by typing:

su

To become a superuser on Linux, you can use the su command. However, sometimes this is not enough, and you still won't have the proper permissions. This is normal — you haven't loaded the superuser's environment variables.

To fix this, simply run:

su -l
# or
su -

https://manpages.debian.org/stretch/login/su.1.fr.html

Sudo usage

Add a user to sudoers

# as root
adduser USERNAME sudo
# then reload session

Launch the last command with sudo

sudo !!

Swap

# should be root
# Turn swap off
swapoff -a

# Create an empty swapfile 10GB
dd if=/dev/zero of=/swapfile bs=1G count=10

chmod 0600 /swapfile
mkswap /swapfile  # Set up a Linux swap area
swapon /swapfile  # Turn the swap on

https://askubuntu.com/a/1177939

Oneliner favicon.ico generator

TO_ICONIFY=IMAGE.png
for i in 48 96 144 192; do convert -background none $TO_ICONIFY -resize ${i}x${i} favicon-${i}x${i}.png; done; convert -background none favicon-* favicon.ico

-background none is used to keep the transparency with png

txt to pdf

apt install paps

paps file.txt | ps2pdf - file.pdf

exiftool rename

exiftool -d '%Y-%m-%d_%H-%M%-S%%-c.%%e' '-filename<CreateDate' .

Reference https://blog.wxm.be/2024/07/26/exiftool-rename-from-date.html

Convert jpg to png with background

convert image.png -background white -flatten -alpha off image.jpg

Reference https://stackoverflow.com/a/5280262

Fast ram folder

mkdir -p /mnt/ram
mount -t tmpfs tmpfs /mnt/ram -o size=4096M # create a (fast) in-ram folder of 4GB

Reset root password

# reboot and press `e` on grub
# add `init=/bin/bash` at the end of the line starting with `linux`
# press `F10` to boot
mount -no remount,rw /
passwd
# enter new password

Custom host resolution

You will need first need to ensure that the file /etc/nsswitch.conf is created

# /etc/nsswitch.conf

hosts:          files dns
networks:       files

Then you can create and use the file /etc/hosts to do a custom host resolution

# /etc/hosts
127.0.0.1       localhost
::1             localhost ip6-localhost ip6-loopback
192.168.1.45    my_server

Share files

# Create a file server, listening in port 7000
while true; do nc -l 7000 | tar -xvf -; done


# Then, at client side (router)

# Send file myfile to server
tar c myfile | nc localhost 7000

# Send directory mydir to server
tar c mydir | nc localhost 7000

Get network packets

# as root
tcpdump -i any

https://www.youtube.com/watch?v=hWc-ddF5g1I

grep -oP '(http|https)://[^<"]+' rss.xml | uniq | xargs -n1 lychee -vv
# or without -n1

https://github.com/lycheeverse/lychee/