Cheat sheet

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Checksusm

Generate and validate checksums in Linux, assuming the exe file is named VxlPro.exe:

# generate:
md5sum VxlPro.exe > VxlPro.md5
# validate:
md5sum -c VxlPro.md5

Generate checksums in Windows 10 (to compare with that in VxlPro.md5)

certutil -hashfile VxlPro.exe MD5

Cross-compile

Cross-compile C++ apps for Arm Linux ref:

sudo apt install qemu-user qemu-user-static gcc-aarch64-linux-gnu binutils-aarch64-linux-gnu build-essential
podman run --rm --arch aarch64 -it alpine
#  ...

Linux configuration

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Passwordless login

Password-less login to a Linux server

# If no ~/.ssh/id_ed25519* file, create one:
ls ~/.ssh/id_ed25519 >/dev/null 2>&1 || ssh-keygen -t ed25519

# copy public key to server
ssh UNAME@HOST 'mkdir ~/.ssh && chmod 700 ~/.ssh'
cat  ~/.ssh/id_ed25519.pub | ssh UNAME@HOST 'cat >> .ssh/authorized_keys'

Debug networking issues

Inspect open ports:

ss -tulpn     | grep LISTEN   # list open ports and processes using them
lsof -i -P -n | grep LISTEN   # list open ports and processes using them
netstat -tulpn                # list open ports and processes using them

nmap -sS <target_IP> # scan remote ports

Other commands: traceroute

Request/see pods/bashrc file for frequently used shortcuts!

Geany Lightweight IDE

• Build from forked source; see the Dockerfile for instructions

Debian package search

# search in package repository (Note: not apt-get):
apt search <package>
# More cumbersome approach, as root/sudo:
apt-get install apt-file
apt-file update
apt-file find filename.h/libname # | grep -F .so

Debian server setup

• Edit /etc/default/console-setup and change font size to 16x32, and reboot!

• Run sudo dpkg-reconfigure keyboard-configuration and follow the interactive visual terminal, leave the first page at its defaults.

• Edit /etc/netplan/50-cloud-init.yaml and set password, and then run sudo netplan apply

• If not using cloudinit, use wpa_supplicant… and e.g. dhclient -v wlan0 instead.

• Get the ip address, ip addr show, and see below for ssh setup

• To use faster 5GHz wifi:

  sudo iw reg set US
  sudo systemctl restart  netplan-wpa-wlan0.service

Fix the terminals blue colour bug:

printf %b '\e]4;4;#6495ed\a'

For more info request/see Ansible #Raspberry-pi configs!

Debian packaging

• notes from: Paul Dreik presentation , youtube

#apt-get install dh-make build-essential dscripts
cd path/to/source/repo
# create debian folder
dh_make --packagename mypackage_0.0.1-2 --native --single --yes
tree debian | less
# Modify debian/[control,copyright,changelog,rules]
dhci -i # manage the package version
dpkg-buildpackage -b -uc
dpkg -i mypackage_0.0.1-2_all.deb
apt-get remove mypackage_0

Fix Gnome regressions

• Extensions for Gnome-3/4: hide-title-bar

• Fix Linux Nautilus file browser regressions:

# Install meld and integrate:
mkdir -p            ~/.local/share/nautilus/scripts/
echo '#!/bin/sh' >  ~/.local/share/nautilus/scripts/meld.sh
echo 'meld $@'  >>  ~/.local/share/nautilus/scripts/meld.sh
chmod +x ~/.local/share/nautilus/scripts/meld.sh

# Restore ability to create text files!:
echo > ~/Templates/NewFile.md

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Git

git vs https vs ssh protocols:

git remote add gitea ssh://git@SERVER:PORT/USERNAME/REPO.git
# vs
git clone https://github/aliraeini/porescale.git
# vs
git clone git@github.com:aliraeini/porescale.git

OCR

OCR / image to text conversion, put all png images in a folder and run: Warning: renames and rewrites your files

rename 's/\ /_/g' *.png
# add `-channel RGB -negate` if needed:
for cas in `ls *.png`; do convert   $cas ${cas%.png}.tif; done
for cas in `ls *.tif`; do tesseract $cas ${cas%.tif}; done