linux

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javascript

Write code like it’s synchrone

let get = async (URL) => {
    const retval = await fetch(URL)
    if (retval.ok) {
        this.playlists = await retval.json()
    } else {
        console.error("doh! network error")
    }
}
get()

Or use promise chaining

fetch(URL)
    .then(stream => stream.json())
    .then(data => this.playlists = data)
    .catch(error => console.error(error))

bash

auto-reply y on installations or fsck repairs

yes | pacman -S <something>

convert all svg files from current path into pngs

find . -name *.svg -exec mogrify -format png {} +

ffmpeg

extract audio-only from video file with ID3 tags

ffmpeg -i <input video>  -metadata title="Title" -metadata artist="Artist" -ab 256k file.mp3

record screen

ffmpeg -f x11grab  -s 1366x768 -i :0.0 -r 25 -threads 2 -c:v libx264 -crf 0 -preset ultrafast  output.mkv

html

<style type="text/css">
    table { page-break-inside:auto }
    tr    { page-break-inside:avoid; page-break-after:auto }
    thead { display:table-header-group }
    tfoot { display:table-footer-group }
</style>

iptables

drop all but accept from one ip

iptables -A INPUT -p tcp --dport 8000 -s 1.2.3.4 -j ACCEPT
iptables -A INPUT -p tcp --dport 8000 -j DROP

drop all incomming ssh connections

iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j DROP

docker

Delete all containers

docker rm $(docker ps -a -q)

Delete all images

docker rmi $(docker images -q)

Delete all dangling images

docker rmi $(docker images -f dangling=true -q)

Create docker network

docker network create mynet

clean up

docker system prune
docker volume rm $(docker volume ls -q --filter dangling=true)

run two docker img container with different names foo and bar and the can reach each other with domain name foo and bar

docker run --name foo --net mynet img
docker run --name bar --net mynet img

git

Set git to use the credential memory cache

git config --global credential.helper cache

Set the cache to timeout after 1 hour (setting is in seconds)

git config --global credential.helper 'cache --timeout=3600'

Set default editor

git config --global core.editor "vim"

create a patch from a modified file

git diff <modified file>  > this.patch

apply a diff patch

git apply this.patch

youtube-dl

search and download first match

youtube-dl ytsearch:damniam

set auto id3 tags

youtube-dl --prefer-ffmpeg --embed-thumbnail --add-metadata --metadata-from-title "%(artist)s - %(title)s" --audio-quality 0 --audio-format mp3 --extract-audio https://www.youtube.com/watch?v=mvK_5nNPKr8

retropie

for rom converting

community/ecm-tools 1.03-1 [Installiert]
    Error Code Modeler

ecm2bin rom.img.ecm

ufw

list all rules

ufw status

disable/enable firewall

ufw enable
ufw disable

systemd

systemctl list-unit-files

vs code

pipe into vs-code

ps fax | grep code | code-oss # for using open source version of vs code

compare open file to clipboard

workbench.files.action.compareWithClipboard).

Nodejs

sleep()

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}


sleep(1000).then(() => console.log("after 1.5 seconds))

async function main() {
    await sleep(20000)
    console.log("do something after 20 seconds")
}

main()

nginx

proxy an api service and add cors headers and basic auth

load_module modules/ngx_http_headers_more_filter_module.so;

events {
   worker_connections 1024;

}

http {
  server {
    listen 80;
    server_name 127.0.0.1;

    
    location / {
        proxy_redirect off;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Authorization "Basic ZW5lcmdpY29zOmVuZXJnaWNvcw==";

        set $cors "1";
    
        if ($request_method = 'OPTIONS') {
            set $cors "${cors}o";
        }
    
        if ($cors = "1") {
            more_set_headers 'Access-Control-Allow-Origin: $http_origin';
            more_set_headers 'Access-Control-Allow-Credentials: true';
        }
    
        if ($cors = "1o") {
            more_set_headers 'Access-Control-Allow-Origin: $http_origin';
            more_set_headers 'Access-Control-Allow-Methods: GET, POST, OPTIONS, PUT, DELETE';
            more_set_headers 'Access-Control-Allow-Credentials: true';
            more_set_headers 'Access-Control-Allow-Headers: Origin,Content-Type,Accept';
            add_header Content-Length 0;
            add_header Content-Type text/plain;
            return 204;
        }
    
        proxy_pass      https://some.url;
    }
  }
}

A Dockerfile would look like this

FROM alpine:3.7

RUN apk --update --no-cache add nginx nginx-mod-http-headers-more

COPY nginx.conf /etc/nginx/nginx.conf
RUN mkdir /run/nginx

EXPOSE 80
CMD nginx -g 'daemon off;'

nginx dynamic reverse proxy for docker swarm mode

events {
        worker_connections 1024;
}

http {
    server {
        resolver 127.0.0.11;
        location ~ /(.*) {
            proxy_redirect off;
            proxy_set_header Host $host;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

            set $upstream $1;

            proxy_pass http://$upstream;
        }
    }
}

knex

insert on duplicated for MariaDB/MySQL

async function insert_on_duplicated(table, data){
	let insert = knex(table).insert(data).toString();
	let update = knex(table).update(data).toString().replace(/^update .* set /i, '');
	return await knex.raw(`${insert} on duplicate key update ${update}`);
}

k8s

list secrets

kubectl -n kube-system get secret

https://blog.alexellis.io/kubernetes-in-10-minutes/

vue

vuejs without shitty webpack

npm install -D  @vue/cli
npx vue init simple web

do spaces with goofy

place key and sected into .aws/credentials

[default]
aws_access_key_id = ...
aws_secret_access_key = ...

and do

./goofys --endpoint ams3.digitaloceanspaces.com melmac /home/ec2-user/t/

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