Cheat sheet

List of freqently used but never remembered commands

Linux General

Mount CDROM

mount -r -t iso9660 /dev/sr0 /media

Curl stuff

curl http://<URL>/folder/file.txt --output file.txt
curl http://<URL>/folder/file.txt -o file.txt

Install from local CentOS media repo if no internet

mkdir /media/CentOS
mount -t iso9660 /dev/cdrom /media/CentOS

Check repo names in brackets [] in the media repo file

cat /etc/yum.repos.d/CentOS-Media.repo

Install from local repo

yum disablerepo=\* --enablerepo=c8-media-BaseOS --enablerepo=c8-media-AppStream install open-vm-tools

List Open Files and Ports

lsof -i -P -n | grep <PORT NUMBER>

Partition, format, and mount a drive on Ubuntu

Reference:

• https://www.howtogeek.com/106873/how-to-use-fdisk-to-manage-partitions-on-linux/

List logical disks and partitions

sudo fdisk -l

Partition the disk

sudo fdisk /dev/sdb

• Press n to create a partition
• Press p or l to create primary or logical partitions
• Press w to write your changes or q to quit

Format the partition

• sudo mkfs -t ext4 /dev/sdb1
• sudo mkfs -t ext4 -N 2000000 /dev/sdb1 - This will manually set the number of inodes to 2,000,000

Mount disk

• mount - Shows what is mounted
• mkdir /mnt/mydrive
• mount -t ext4 /dev/sdb1 /mnt/mydrive

Get disk's UUID

ls -al /dev/disk/by-uuid/
or
blkid

Mount at boot

Add the following line to your /etc/fstab file adjusting the UUID to your device's id and the directory to where you want to mount:

UUID=811d3de0-ca6b-4b61-9445-af2e306d9999 /mnt/mydrive ext4 defaults 0 0

mount -a - remounts filesystems from /etc/fstab

Git/Hub Config

1. Setup Github ssh keys

ssh-keygen -t rsa -b 4096 -C "EMAIL Address"
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_rsa
ssh -T [email protected]

2. Add keys to account

[https://docs.github.com/en/github/authenticating-to-github/adding-a-new-ssh-key-to-your-github-account]

3. Push SSH keys to another host if required

scp -r .ssh/ <NAME>@<HOST>:~

4. Install Git if required

sudo yum -y install git

5. Git config

git config --global color.ui auto
git config --global user.email "<NAME>@users.noreply.github.com"
git config --global user.name "<NAME>"

Run Git pull over subdirectories

for i in */.git; do ( echo $i; cd $i/..; git pull; ); done

Ansible

ansible <HOST> -m ping
ansible <HOST> -a "/bin/echo hello"
ansible-playbook <playbook>.yml --tags <TAG NAME>

Get Ansible facts direct

ansible <hostname> -m ansible.builtin.setup

Create Role

Create a repo in Github without readme etc e.g. below using test-role

ansible-galaxy init --init-path . test-role
cd test-role
git init
git add .
git commit
git remote add origin [email protected]:nicholasrodriguez/test-role.git
git branch -M main
git push -u origin main

Goto [https://galaxy.ansible.com] and import

.vimrc

set shiftwidth=2
set expandtab
set tabstop=4
color desert

AWS

CLI Install

curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
unzip awscliv2.zip
sudo ./aws/install

Configure

aws configure

Docker

Install

sudo dnf install -y yum-utils
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
sudo dnf -y install docker-ce docker-ce-cli containerd.io
sudo systemctl enable --now docker

Manage Docker as a non-root user

sudo usermod -aG docker $USER
newgrp docker

Test Docker

docker info
docker run hello-world

Install Docker Compose

sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose

Test docker-compose

docker-compose --version

Connect to Remote Docker Engine

Download cert

mkdir -pv ~/.docker
unzip cert.zip -d ~/.docker

Set env var for remote host

export DOCKER_HOST=tcp://<docker host>:<port> DOCKER_TLS_VERIFY=1

Or create context and connect remotely

docker context create \
    --docker host=ssh://[email protected] \
    --description="Remote engine" \
    my-remote-engine

Switch context

docker context use my-remote-engine

Create

Create container interactively

sudo docker run -i -t centos:8 bash

Install stuff then exit

docker ps -a
docker commit <CONTAINER ID> infra-tools

Run containers

Run another one

sudo docker run -i -t infra-tools bash

Connect to a stopped container

docker start -ia <CONTAINER ID>

Connect to a running container

docker exec -it <container name> /bin/bash

Mount local filesystem to a container

docker run -it -v $(pwd)/:/mnt/ mcr.microsoft.com/azurestack/powershell

Export

Export to a file

docker save -o infra-tools.tar infra-tools:latest

Stop all containers

docker container stop $(docker container ls -aq)

Remove all containers

docker container rm $(docker container ls -aq)

CentOS 8 to Rocky Linux

https://docs.rockylinux.org/guides/migrate2rocky/

Prep the box

Got some odd package clashes on my personal CentOS 8 instances

sudo yum -y remove docker-ce
sudo yum -y remove docker-ce-cli 
sudo yum -y remove containers-common
sudo yum -y remove containerd.io
sudo yum -y remove rpm-build

Clone the tools

cd ~
git clone https://github.com/rocky-linux/rocky-tools.git
cd rocky-tools/migrate2rocky
chmod u+x migrate2rocky.sh

Convert to Rocky

cd ~/rocky-tools/migrate2rocky
sudo ./migrate2rocky.sh -r

Terraform

Windows Install

Plop the executable in

C:\Users\<USER NAME>\AppData\Local\Microsoft\WindowsApps

Python