JSELEC

JSelec: a technical notes blog.

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  • How To Use Systemctl to Manage Systemd Services and Units

    All credits to: @ Digitalocean.com Justin Ellingwood   Introduction Systemd is an init system and system manager that is widely becoming the new standard for Linux machines. While there are considerable opinions about whether systemd is an improvement over the traditional SysV init systems it is replacing, the majority of distributions plan to adopt it or…

  • TK102 GPS tracker configuration

    TK102 GPS tracker configuration

    We are going to use a KPN prepaid SIM card. The pin code is removed using a cell phone and mobile internet is activated. We will transfer the data via GPRS connection to a GPS server called Traccar. The server is free downloadable for any platform. Make sure the battery of the GPS is well…

  • Ubuntu error: A job is running for dev-mapper-cryptswap1.device

    (Thanks to: Ubuntuhak ) If you notice that booting Ubuntu takes a long time and you see the following error message on the booting screen after pressing ‘ESC’, A job is running for dev-mapper-cryptswap1.device (50s / 1m30s) This is caused by the system looking for an encrypted swap partition, however most likely you have not…

  • Chrome browser in Ubuntu

    Chrome browser in Ubuntu

    Follow the instruction for installation: Add Key: wget -q -O – https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add – Set repository: sudo sh -c ‘echo “deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main” >> /etc/apt/sources.list.d/google-chrome.list’ Install package: sudo apt-get update sudo apt-get install google-chrome-stable

  • PXE Server on Existing Network

    Many thanks to Sebastian Krysmanski’s original post! The Goal At the end of this article you’ll have a working PXE server that lets you boot memtest86+ over a network. The goal is to have a simple but working solution. This is why I’m using memtest. It consists of just one file and thus is easy to…

  • Change linux hostname

    How to change the hostname of the system sudo hostname (new hostname) Change old hostname also in the following file: sudo nano /etc/hosts

  • OpenVPN shortcut

    This script will show your current WAN IP address before and after connecting to your VPN. VALID_IP=”123.123.123.123″ #this is the correct IP you should be connected to myip=”$(dig +short myip.opendns.com @resolver1.opendns.com)” echo “My current WAN/Public IP address: ${myip}” echo “Starting OpenVPN connection” sleep 1 sudo openvpn –config ~/path/to/VPNConfig.ovpn –daemon echo “Establishing connection…” sleep 8 myip=”$(dig…

  • Add user to sudo- ers file

    Open the sudoers file: sudo visudo will open the /etc/sudoers file in the editor defined in $EDITOR (probably GNU nano – set the variable if it’s not what you want, eg export EDITOR=”nano” and try sudo visudo again). Add the below line to the end of the file. username ALL=(ALL) ALL # Change the user…

  • OpenVPN running in background

    Simply run the following command in terminal: sudo openvpn –config ~/Documents/path-to/VPNConfig.ovpn –daemon It is not nescessary to leave the terminal open! To kill the connection, stop the process. Identify the correct process ID number. ps aux | grep openvpn Kill the process. sudo kill [id-number]

  • Raspberry Pi Static ip address

    Edit /etc/dhcpcd.conf sudo nano /etc/dhcpcd.conf Add the following rows add the bottom of the text. Leave the default text intact. interface eth0 static ip_address=192.168.1.99 interface wlan0 static ip_address=192.168.1.100 static routers=192.168.1.1 static domain_name_servers=202.62.64.3 8.8.8.8 Reboot

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