bashCheatSheet.Rmd

---
title: "bash Cheat Sheet"
author: "Anthony Atto"

output:
  html_document:
    code_folding: hide
    toc: true
    toc_float:
      collapsed: false
    md_extensions: +raw_html
---

```{r setup, warning=FALSE, message=FALSE}
# set knitr options
knitr::opts_chunk$set(echo = TRUE, warning = FALSE, message = FALSE)
require(remoji)
require(htmltools)
```

## Overview  
This is a document I created to help me remember some key commands and uses for BASH.

## Basics  
### Philosophy
command.  options.  arguments.  

### Navigation  
* `cd`  
* `ls`
* `cat`
* `echo`

### Help  

### Profiles

## `r HTML(paste("Major", emoji("key")))`  
### cron
* `crontab`
* `-e`, `-l`


## SSH & Key Management  
### Generate a Key  
> `ssh-keygen -t rsa`  

This generates both a public and private key

### .ssh Folder Location  
> `/Users/ARA/.ssh`  

This directory is hidden in the users home directory.  the `.` hides it in the finder and will not be shown with just the `ls` command.  `ls -a` must be used to show hidden files.  

### Copy a Key to the Server  
#### Linux  
> `ssh-copy-id user@server.com`

Copying keys on a Linux machine is easy.  It will automatically put the public key in the server's .ssh folder for you.

#### Mac
Mac is more complicated.  You have to copy a key to the server, then move the key into the .ssh directory.  
  
1.  Use Secure Copy  

> `scp [key location] user@server.com:`

Use secure copy to send the public key to the server.  An example:  `scp .ssh/id_rsa.pub anthony@anthonyatto.com:`.  Be sure to include the `:` at the end of the line.

2.  Log Into Server  

> `ssh [user@server.com]`

SSH into the server so that you can then move the public key to the right place yourself.  An example: `ssh anthony@anthonyatto.com`.  You will likely be prompted for a password (or will automatically be logged in if you have a keypair set up).  

3.  Store the Public Key in `authorized_keys`  

> `mkdir ~/.ssh`
`cat id_rsa.pub > .ssh/authorized_keys`  

Check that the public key is where you expected it to be (in `$HOME`).  If one is not already there, create an `.ssh` directory.  Then, move the public key to `.ssh/authorized_keys`.

### Connect to the Server using Key  
> `ssh -i [private key location] [user@server.com]`

Connects after matching private key on local host and public key on server.  An example:  `ssh - i ~/.ssh/id_rsa anthony@anthonyatto.com`.  The `-i` option tells `ssh` to 'identify' the public key on the server.  

### SSH Shortcut
> `Host anthony`    
> `  User anthony`  
> `  Hostname anthonyatto.com`  
> `  IdentityFile ~/.ssh/id_rsa`  

then, simply type `ssh anthony` and it will login automatically.