Kartones

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

rgreenjr

-- show running queries (pre 9.2)
SELECT procpid, age(clock_timestamp(), query_start), usename, current_query 
FROM pg_stat_activity 
WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%' 
ORDER BY query_start desc;

-- show running queries (9.2)
SELECT pid, age(clock_timestamp(), query_start), usename, query 
FROM pg_stat_activity 
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' 

bastman

Docker - How to cleanup (unused) resources

Once in a while, you may need to cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

ipbastola

JQ to filter JSON by value

Syntax: cat <filename> | jq -c '.[] | select( .<key> | contains("<value>"))'

Example: To get json record having _id equal 611

cat my.json | jq -c '.[] | select( ._id | contains(611))'

Remember: if JSON value has no double quotes (eg. for numeric) to do not supply in filter i.e. in contains(611)

bbengfort

Ben's VirtualEnv Cheatsheet

This cheat sheet describes my usage/implementation of virtualenv with virtualenv wrapper and the bash foo that I added with the help of many blogs to make it all tick together in fun land.

Quick Reference

$ echo $WORKON_HOME
/Users/benjamin/.virtualenvs

$ echo $PROJECT_HOME

alexellis

This guide has moved to a GitHub repository to enable collaboration and community input via pull-requests.

https://github.com/alexellis/k8s-on-raspbian

Alex

angstwad

# Copyright 2016-2022 Paul Durivage
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,

hofmannsven

Raspberry Pi

• Related tutorial: http://raspberrypiguide.de/
• Command Line Cheatsheet: https://gist.github.com/hofmannsven/8392477

Setup

Find all available devices arp -a

Locate Raspberry (b8:27:eb) in Network: Pi Finder

SSH

hofmannsven

Command Line Crash Course

Related tutorials

• http://cli.learncodethehardway.org/book/
• https://www.codecademy.com/courses/learn-the-command-line

Cheatsheets

• Linux auf einem Blatt
• Fasd

tsabat

Prereq:

apt-get install zsh
apt-get install git-core

Getting zsh to work in ubuntu is weird, since sh does not understand the source command. So, you do this to install zsh

wget https://github.com/robbyrussell/oh-my-zsh/raw/master/tools/install.sh -O - | zsh