πŸ“š node [[gnu linux]]

GNU+Linux is a family of operating systems, featuring the Linux kernel and GNU stuff. They are often called simply Linux. I do not have a strong opinion on that, but on this wiki I will differentiate the kernel and this family of OSes.

= Distros I used for noticeable time

  • Linux Mint Cinnamon
  • Antergos
  • Open SUSE
  • Linux Mint MATE

And some others.

= What I want to try

  • GNOME
  • elementary OS

= Links => https://wion.com/notes/embracing-linux | Embracing Linux

This article is for those, like me, who want to get started in Linux and need some perspective on how to approach it. The article is not a how-to explainer; it is a general lay of the land for one particular situationβ€”mineβ€”and requires more investigation on the part of the individual. But still, maybe it helps.

=> https://hackaday.com/2021/07/27/classroom-surplus-becomes-linux-powerhouse/ | CLASSROOM SURPLUS BECOMES LINUX POWERHOUSE img { https://hackaday.com/wp-content/uploads/2021/07/smart-linux-featured.jpg?w=800 }

The SMART Response XE is a handheld computer that was originally sold for use in the classroom as a terminal for pupils taking tests. It’s now cheap enough on the surplus market to have become a target for experimenters, and we’ve seen them with a variety of cool hacks. We particularly like what [chmod775] has done with it, putting a VT100 terminal emulator on the device and hiding a NanoPi Neo Air single board computer in the battery bay. Powered from a USB battery bank, it gives a fully-featured Linux terminal in the palm of the hand. We see it running an Ubuntu LTS version, and it’s clear that it’s a functional and usable device.

β₯… node [[gnu]] pulled by user

gnu

β₯… node [[linux]] pulled by user

Linux

The bog standard free software operating system. Runs everywhere. Good. Fast. Monolithic C kernel.

Understanding Linux performance Best Linux tips and tricks

Table of Contents

related [[infra]]

docker [[docker]]

[2018-06-15] docker system prune to cleanup

[2021-01-12] figuring out what takes disk space docker images | awk '{print $3}' | xargs docker inspect | less [[docker]]

[2021-02-12] Docker compose port mapping - Stack Overflow

If you want to bind to the redis port from your nodejs container you will have to expose that port in the redis container:

version: '2'
services:
  nodejs:
    build:
      context: .
      dockerfile: DockerFile
    ports:
      - "4000:4000"
    links:
      - redis
  redis:
    build:
      context: .
      dockerfile: Dockerfile-redis
    expose:
      - "6379"
The expose tag will let you expose ports without publishing them to the host machine, but they will be exposed to the containers networks.

[2021-04-14] apt-get clean and other strategies for keeping image size small? Β· Issue 35 Β· rocker-org/rocker [[docker]]

ok, so for debian/ubuntu images don't really need autoclean – it's already run automatically

[2021-05-02] Attach and Detach from Docker Container | HowToProgram [[docker]] [[drill]]

In general, to detach from a Docker container and leave it running, we can use the CTRL-p CTRL-q key sequence.

systemd [[systemd]]

debugging: systemctl --failed, journalctl

logs – for individual jobs you can see them via status (or sdj)
presistent is not showing anythin by default?

profiling: systemd-analyze blame

networking [[network]]

who uses local port

sudo ss -tulpn | grep 5060
sudo ss -anpt  | grep 8640

testing if port is open

netcat -l 5559

one the other machine

echo "TEST" | netcat host 5559

[2020-06-15] linux - Test if a port on a remote system is reachable (without telnet) - Super User

Nice and verbose! From the man pages.
Single port:
nc -zv 127.0.0.1 80

testing if port is open

apt

install build dependencies: sudo apt-get build-dep package

cron [[cron]]

[2018-02-26] if cron fails to start a job, it will send the output to local mail

grep cron /var/log/syslog
tail -f /var/log/syslog | grep cron

[2018-05-10] mail subject – use bash comment operator

*:* TestJob; cron command

mind the space after colon!

sandboxing [[sandbox]]

docker is excellent for quick sandboxes (just use ubuntu:latest image or something) [[docker]]

firejail for network sandbox [[network]] [[testing]]

  • doesn't require root!
  • firejail --noprofile --net=none

udev [[udev]]

udevadm info /dev/sdc2

[2019-03-07] when you update rules file sudo udevadm control --reload-rules

[2019-03-07] to trigger the target script sudo udevadm trigger

[2017-05-08] Gateway 0.0.0.0 means that the subnet is link-local i.e. there is no gateway involved, the packets are delivered directly to the target [[network]]

-----

[2018-06-08] Linux ignores the setuid bit on all interpreted executables (i.e. executables starting with a #! line).

ok apparently setuid shell scripts are quite risky…

[2020-01-29] linux - How to make htop sort by PID

press > and select RES

[2020-01-24] logs - View stdout/stderr of systemd service [[systemd]]

Note that using the standard logging mechanism like this will not create persistent logs by default. To do that, you'll need to create /var/log/journal, and then run sudo systemctl restart systemd-journald

[2020-01-29] How to read memory usage in htop? - Server Fault [[drill]]

https://serverfault.com/questions/517483/how-to-read-memory-usage-in-htop

Hide user threads (shift + H) and close the process tree view (F5), t

[2020-12-04] linux - prevent system freeze/unresponsiveness due to swapping run away memory usage - Super User

If a process demands a lot of memory, the system moves all other process to the swap file. Including it seems, necessary processes like the X11 server or the terminal.

[2018-04-27] guide to XKB

-

whereis command [[habit]]

πŸ“– stoas
β₯± context