Dev Cheat Sheets

Even the best of us sometimes forget common administrative commands on the terminal when we haven’t used them in a while. I record down those that I find useful here for my own reference. You may find some of these helpful as well. You may notice that some extremely common commands for some services are not listed here, this is because they are usually remembered from heart and are not listed to avoid cluttering the space.

Linux

> General

Re-index locate database
```
updatedb
```
cat gzip file without decompressing
```
zcat <file>
```
Read in environment variables with eval (ssh-agent example)
```
eval $(ssh-agent)
```

> Development

curl an application with JSON payload

curl -H "Content-Type: application/json" -d '{"text": "Hello world"}' http://localhost:3000/api

Get exit code of last command
```
echo $?
```
Set the exit code of a pipeline to the first command with non-zero status and result in immediate exit
```
set -o pipefail && <other commands> | <more commands>
```

> Administration

Get uptime of system
```
uptime
```
Get users who are logged on
```
who
```
Get info about a user
```
id <user>
```
Get group information about a user
```
groups <user>
```
Get current time zone
```
timedatectl status
```
List available time zones
```
timedatectl list-timezones
```
Update time zone of system
```
timedatectl set-timezone Zone/SubZone
```

> System

Get hostname information
```
hostnamectl
```
Get release information
```
cat /etc/*-release
```
List CPU architecture information
```
lscpu
```
List PCI devices
```
lspci
```

> Logging

Get kernel ring buffer logs
```
dmesg -H
```
Get boot logs
```
cat /var/log/boot.log
```
Get systemd logs
```
journalctl
```

Security logs

cat /var/log/secure # or /var/log/auth.log

> Security

Checking/modifying sudo users
```
visudo
```

> Arch Linux

Installation without prompts (usually for AUR)
```
pacman -S --noconfirm <package>
```
Manage .pacnew and .pacsave files
```
pacdiffviewer
```
Get pacman logs
```
cat /var/log/pacman.log
```

Postgres

> Connecting

To connect to a Postgres server locally
```
psql -U <username>
```
To connect to a Postgres server on a remote machine
```
psql -h <hostname> -U <username> -d <database>
```

> Commands

\c <database>: Connect to a database
\d <table>: Show table definition
\l: List databases
\dn: List schemas
\q: Quit

> Administration

\du: List users
create role <user>: Create role with existing username

Docker

> Docker

Build a Docker image with Dockerfile in the current directory
```
docker build -t <image_name> .
```
List Docker images
```
docker images
```
Pull a Docker image
```
docker pull <image_name>
```
Run a Docker container in the background, with port mapping, container name, and environment variables. Tag name is defaulted to latest if unspecified.
```
docker run -d -p <container_port>:<host_port> --name <name> -e <env_name>:<env_value> <image_name>:<tag_name>
```
Run a Docker container interactively, bash in this example
```
docker run -it <name> bash
```
List containers. The -a flag shows all containers.
```
docker ps -a
```
Monitor logs from container
```
docker logs <name>
```
Stop a container
```
docker stop <name>
```
Remove a container
```
docker rm <name>
```
Remove an image
```
docker rmi <image_name>:<tag_name>
```
To run a Docker container inside a Docker container, pass in the Docker socket as a volume
```
docker run -v /var/run/docker.sock:/var/run/docker.sock
```
Remove all stopped containers
```
docker container prune
```
Remove dangling images that are not tagged and being used by any containers
```
docker image prune
```
Remove all images not referenced by an existing container
```
docker image prune -a
```

> Docker Compose

Bring up containers in detached mode
```
docker-compose up -d
```
Build components and bring containers up in detached mode
```
docker-compose up --build -d
```
Bring down containers
```
docker-compose down
```
Get status
```
docker-compose ps
```

Vagrant

Create a Vagrant configuration file for Ubuntu 14.04 (Trusty Tahr) 64-bit virtual machine image
```
vagrant init ubuntu/trusty64
```
Start VM based on Vagrantfile
```
vagrant up
```
SSH into VM
```
vagrant ssh
```
SSH into named VM
```
vagrant ssh <vm_name>
```
Get port forwarding information of a machine
```
vagrant port <vm_name>
```
Type exit to quit the SSH session
To output SSH connection details
```
vagrant ssh-config
```

SSH from command line using information above

ssh vagrant@127.0.0.1 -p 2222 -i /path/to/private/key

Get status of machines
```
vagrant status
```
Destroy VM
```
vagrant destroy <vm_name>
```
Sample Vagrantfile

# -*- mode: ruby -*-
# # vi: set ft=ruby :

Vagrant.configure("2") do |config|

  config.vm.define "web" do |web|
    web.vm.box = "bento/ubuntu-14.04"
    web.vm.network "forwarded_port", guest: 80, host: 8080
    web.vm.synced_folder "./html", "/var/www/html/class"
    web.vm.provision :shell, path: "bootstrap.sh"
  end

  config.vm.define "db" do |db|
    db.vm.box = "bento/ubuntu-12.04"
    db.vm.network "forwarded_port", guest: 3306, host: 3306
    db.vm.hostname = "dbserver"
    db.vm.provision :shell, path: "db-bootstrap.sh"
  end

end

Jekyll

Serve a Jekyll project locally:
```
bundle exec jekyll serve
```

Build for production

JEKYLL_ENV=production bundle exec jekyll build

Chef

Generate new cookbook
```
chef generate cookbook <name>
```
Execute cookbook with config file and JSON data
```
chef-solo -c <config_file> -j <json_file>
```
Converge based on cookbook
```
kitchen converge
```
Get instances convergence status
```
kitchen list
```
Remove instances
```
kitchen destroy
```

NPM

Install a package globally
```
npm install -g <package_name>
```

dpkg

Build package
```
dpkg-deb --build myapp_1.0
```
Get information about package
```
dpkg-deb -I myapp_1.0.deb
```
Get contents of package
```
dpkg-deb -c myapp_1.0.deb
```
Install package
```
dpkg-deb -i myapp_1.0.deb
```

apt

List installed packages
```
apt list --installed
```
Get information about package
```
apt show <package_name>
```

Gem

Install package without ri and rdoc
```
gem install --no-ri --no-rdoc <name>
```

AWS

Configure AWS credentials
```
aws configure
```
Get information about EC2 instances in us-east-1 region
```
aws ec2 describe-instances --region us-east-1
```

Run an EC2 instance with specified AMI

aws ec2 run-instances --image-id <ami_id> --instance-type t2.micro --region
us-east-1

Validate CloudFormation template

aws --region us-east-1 cloudformation validate-template --template-body
file://./ec2.yml

Create CloudFormation stack

aws --region us-east-1 cloudformation create-stack --stack-name <name>
--parameters file://./ec2-parameters.json --template-body file://./ec2.yml

Kubernetes

> Minikube

Start up Minikube
```
minikube start
```
Read in Minikube env vars
```
eval $(minikube docker-env)
```
Open service in browser
```
minikube service <service_name>
```
Open dashboard
```
minikube dashboard
```

> kubectl

Create deployment from deployment file
```
kubectl create -f <deployment_file>
```

Create deployment from Docker image

kubectl run <deploy_name> --image=<docker_image>:<tag> --port=<port>

Update resources
```
kubectl apply -f <deployment_file>
```
Get deployments
```
kubectl get deployments
```
Get pods
```
kubectl get pods
```
Get services
```
kubectl get services
```

Create service from deployment and expose outwards

kubectl expose deployment <deploy_name> --type=LoadBalancer

Vim

Add new mapping with leader key (example: ack)
```
map <Leader>g :Ack<space>
```
Add new mapping with control key (example: Ctrl-F)
```
map <C-f> :CtrlP<cr>
```

ImageMagick

Resize image by 50% of original size

convert input.png -resize 50% output.png

Contents

Linux

> General

> Development

> Administration

> System

> Logging

> Security

> Arch Linux

Postgres

> Connecting

> Commands

> Administration

Docker

> Docker

> Docker Compose

Vagrant

Jekyll

Chef

NPM

dpkg

apt

Gem

AWS

Kubernetes

> Minikube

> kubectl

Vim

ImageMagick