kido-ih

[kido-ih]

Force time sync (systemd v213+)

systemctl restart systemd-timesyncd.service

[kido-ih]

Helm

### List repositories helm repo list

### Add helm repository 'foo' helm repo add foo https://charts.example.org

### Deploy 'foo' chart from repo/projectname in to currently selected cluster (kubectl config get-contexts) helm upgrade --install foo repo/projectname

[kido-ih]

Get telegram chat ID

Ensure your bot has been invited to chat and has enough permissions to read chat history

curl https://api.telegram.org/bot<YOUR_BOT_TOKEN>/getUpdates

You may need to send a message to the chat to get any new update with chat ID

[kido-ih]

NextCloud LOCKED error fix

docker exec -it nextcloud_app su - www-data -s /bin/sh -c "/var/www/html/occ maintenance:mode --on" docker exec -it nextcloud_db psql -U oc_nextcloud --dbname nextcloud SELECT * FROM oc_file_locks; DELETE FROM oc_file_locks WHERE lock=1; docker exec -it nextcloud_app su - www-data -s /bin/sh -c "/var/www/html/occ maintenance:mode --off"

[kido-ih]

Connect to SMTP server and send e-mail with openssl/netcat/telnet

Option A)

echo -ne "\0username@domain.org\0password" | base64 openssl s_client -starttls smtp -connect smtp.example.org:587 EHLO smtp.example.org AUTH PLAIN <echo to base64 output here>

Option B)

echo -ne "username" | base64 echo -ne "password" | base64 openssl s_client -starttls smtp -connect smtp.example.org:587 EHLO smtp.example.org AUTH LOGIN <base64 encoded username> <base64 encoded password>

Sending e-mail:

Once logged in, continue with following:

MAIL FROM: username@domain.org rcpt to: addressee@example.com DATA From: username@domain.org To: addressee@example.com Subject: Testing e-mail

Hello, This e-mail is only a test. . QUIT

[kido-ih]

Bootable USB on macOS

curl http://example.org/image.iso -o image.iso

diskutil eraseDisk MS-DOS FAT32 disk2

diskutil umount /dev/disk2s2

hdiutil convert -format UDRW -o image image.iso

sudo dd if=image.dmg of=/dev/disk2 bs=4m; sync

diskutil eject disk2

[kido-ih]

terraformer examples (to be completed)

Import all resources from AWS in region eu-north-1

terraformer import aws --regions=eu-north-1 --resources="*"

[kido-ih]

Clone repo with specific key

This is how you can clone some repository using a specific private OpenSSH key:

# GIT_SSH_COMMAND="ssh -o PreferredAuthentications=publickey -o UserKnownHostsFile=/dev/null -o PubkeyAuthentication=yes -o User=git -o StrictHostKeyChecking=no -o CheckHostIP=no -o Hostname=gitlab.com -i /root/.ssh/id_rsa.pem" git clone git@gitlab.com:example/repository.git /var/www/example.org

[kido-ih]

postgres cheatsheet

# start interactive postgres cli psql -U postgres

# connect to database foo \c foo;

# list all databases \l

# list all users \du

# list all tables \dt

# create role 'foo' CREATE ROLE foo;

# create database 'foo' with owner bar CREATE DATABASE foo WITH OWNER bar;

# select id,username,password fields from users table SELECT id,username,password from users

# update field password of id 123 in users table UPDATE users SET password = 'somevalue' WHERE id = '123'; # remove all tables in current database DO $$ DECLARE   r RECORD; BEGIN   FOR r IN (SELECT tablename FROM pg_tables WHERE schemaname = current_schema()) LOOP     EXECUTE 'DROP TABLE ' || quote_ident(r.tablename) || ' CASCADE';   END LOOP; END $$;

[kido-ih]

Limiting playbook run to multiple hosts

Wonder how you can limit running playbooks to a multiple hosts at once? Manpage doesn't describe that, but I found a hack for this:

ansible-playbook -l 'host1:host2' main.yml

[kido-ih]

Ansible optimized config

Use this ansible.cfg to make your ansible work way more efficient than it comes out-of-box:

[defaults]

gathering = smart

inventory = ./hosts.yml

host_key_checking = False

deprecation_warnings = False

[ssh_connection]

ssh_args = -C -o ControlMaster=auto -o ControlPersist=10m -o IdentitiesOnly=yes

pipelining = True

transfer_method = piped

[kido-ih]

ImageMagick cheatsheet

Create Grayscale multipage TIFF from JPEGs and reduce it's size

convert foo.jpg +append bar.jpg -resize 90% -colors 2 -colorspace Gray -type Palette baz.tif

[kido-ih]

ffmpeg for iOS

Fucking finally found the working set of parameters for ffmpeg in order to convert media to format compatible with playing on iOS devices! Yay!

ffmpeg -an -i input.mp4 -vcodec libx264 -crf 25 -preset slow -codec:a aac -qscale:a 1 -pix_fmt yuv420p -profile:v baseline -level 3 output.mp4

Possible values for preset (faster option gives larget output filesize): -preset: ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow, placebo

Possible values for crf (lower number - larger output filesize): -crf: 0-51

[kido-ih]

# Docker cheat sheet

 - List images # docker images

 - List running containers # docker container ps

 - List all containers # docker container ps -a

 - List volumes # docker volume ls

 - Stop container `foo` # docker container stop foo

 - Kill container `foo` # docker container kill foo

- Execute command `bar` in running container `foo` # docker exec -it foo bar

- Start stopped container `foo` # docker container start `foo`

- Run container from image `bar` in the background # docker run -d bar

 - Run container from image `bar` in the background, overriding defined ENTRYPOINT # docker run -d bar --entrypoint /bin/bash

 - Configure running container `foo` to restart automatically unless stopped # docker update --restart unless-stopped foo

- Remove all unused stuff # docker system prune

[kido-ih]

Adjust natural scrolling in MATE window manager

Edit /usr/share/X11/xorg.conf.d/40-libinput.conf

Find section with the device you want to adjust and add following line in this section:

Option “NaturalScrolling” “on”

Save file and restart X server or reboot your machine

[kido-ih]

Send emails from linux host

# apt install msmtp

/etc/msmtprc:

defaults port 587 tls on tls_trust_file /etc/ssl/certs/ca-certificates.crt

account <account-name> host smtp.example.org from <your-email> auth on user <your-username> password <your-password>

account default : <account-name>

echo -e "Subject: test email" | msmtp recepient@example.org

[kido-ih]

Adjust pinentry program for gpg-agent

# Add following line to the ~/.gpg-agent.conf:

pinentry-program /path/to/pinentry-program

# And restart the GPG agent in order to make new settings take effect:

gpgconf --reload