Raspberry Pi Cheat Sheet

Table of Contents


How to install an operating system

The remains of this page assume that you are running Raspbian as operating system of your Raspberry Pi. In fact, However, there are several operating systems running on a Raspberry Pi that conform to your needs in a better way.
For information of available operating systems and installation instructions, please follow the links below on the website of the Raspberry Pi Foundation.

  1. Operating systems information and downloads
  2. Operating system installation guide
Here you can download any version of Raspbian:


Prepare your installation before first boot

Enable SSH

SSH (Secure SHell) enables you to log into your Raspberry Pi remotely over network. Linux and MacOS come within SSH preinstalled. For Windows, please install a tool like PuTTy.

Create an empty file named ssh in the BOOT partition of your SD card after installing the Raspbian image. SSH then will be enabled when you boot.
You can enable/disable SSH later using Raspbian's raspi-config tool.

> sudo raspi-config

When your Raspberry Pi has booted and is connected to a network, you can open a remote terminal from a computer in your network with the SSH command. Change the IP address to the address of your Pi:

> ssh pi@192.168.0.42

Remember the default credentials for login:
User: pi
Password: raspberry

Setup Wifi

Before first boot, place a file named wpa_supplicant.conf in the BOOT partition of your SD card. The file must contain the following information. Make sure to use uppercase letters for country code and to have no spaces around the = symbols.

# File wpa_supplicant.conf (Raspbian Stretch)
country=DE
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
       ssid="wlan-bezeichnung (ssid)"
       psk="passwort"
       key_mgmt=WPA-PSK
}
The file will be copied to /etc/wpa_supplicant/wpa_supplicant.conf on first boot. You can adjust WiFi-settings in Raspbian by editing this file.
You may have multiple network={...} entries for multiple WiFis.


The terminal

The terminal is the main interface to the system of your Raspberry Pi. You can browse its file system, edit files and run commands. If you are logged in by SSH or running Raspbian headless, the terminal is your only interface. But even if you are using a window manager, you often will have to run commands in a terminal. Here are some hints and commands how to use the terminal.

Working with the terminal

When you open a terminal - often also called shell - you are located in your user directory, usually the home directory of the user pi. Working in the terminal, you are always located in a directory, called the working directory. Type the command

> pwd
to print the current working directory /home/pi.
In Linux, file paths use the / symbol to separate directories. Special directories are the root directory /, your home/user directory ~, your current working directory . and parent directory of your current working directory ...

There are several convenience keys when using the shell. Hit the Tab button to auto-complete commands and filenames. Use the Up- and Down-Arrow keys to recall the latest commands.

Useful commands

Commands usually have various options. Most commands are described by man-pages. If no man-page exists, try to run the command with the flag --help. Please refer to this help system, if you require a command to behave differently.

# show manual page for command
man command

# list elements of a directory (working directory if no directory specified)
ls directory_name

# list also hidden elements of a directory
ls -a

# list elements of a directory with lots of information (permissions, filesize...)
ls -l

# change directory, e.g. 'cd ..' will change to parent directory
cd directory_name

# create directory
mkdir directory_name

# delete directory
rmdir directory_name

# copy file 
cp file_name copied_file_name
cp file_name directory_to_copy_to

# rename or move file or directory
mv file_name new_file_name
mv file_name directory_to_move_to

# delete file (deletions are permanent, no trash bin here!!)
rm file_name

# file editor running in the terminal
nano file_name

# show configuration of network devices, e.g. to get 
# IP address of WiFi (wlan0) or ethernet (eth0) module
ifconfig


Security

When your Raspberry Pi is exposed to the public, you are responsible for securing your device. There are many ways to attack or hack a device like the Raspberry Pi that are impossible to account for. However, you should prevent the most trivial ways to get into your Pi. While changing or destroying your work is annoying, the device may be used to attack others.

Here is a list of issues that you should account for:

  • Make sure that your device is physically inaccessible. This prevents access to your SD card (or swapping in another SD card), to the USB and network connectors.
  • Change the default password.
  • Substitute readable WiFi passwords with keys.
  • Disable WiFi and/or Bluetooth if not used.

Change default password

Change the default password by typing the following command in a terminal:

> passwd
Follow the instructions of the command to change the password.

Remove readable WiFi passwords

WiFi passwords are stored in readable form. Please substitute the readable passwords with keys that are generated by the following command:

>  wpa_passphrase MyWifiSSID MyPassword
The output contains a network configuration that you can copy to your /etc/wpa_supplicant/wpa_supplicant.conf file. Don't forget to delete the readable password.

network={
	ssid="MyWifiSSID"
	#psk="MyPassword"
	psk=bd50bf1bf2b27d2c6cfcc0aec0145007d4bfb8beb259314f377870d4bd66d003
}

Disable WiFi and Bluetooth

If you don't require WiFi and/or Bluetooth it is safest to disable those services. The easiest way to disable them is to edit the file /boot/config.txt and add the following lines. (A version of Raspbian not older than 2017 is required)

# disable WiFi
dtoverlay=pi3-disable-wifi

# disable Bluetooth
dtoverlay=pi3-disable-bt
If you disable Bluetooth, it is also necessary to disable the system service that initialises the modem so it doesn't use the UART:

> sudo systemctl disable hciuart
Reboot your device.


Installing software (aptitude)

Raspbian comes with the package manager aptitude, which lets you install additional software. The package manager keeps track of all software installed and handles all dependencies, i.e. software (libraries, binaries etc.) that a software depends on.

Update

Before you install any new software, you should update the list of available packages:

> sudo apt-get update
Then update the software already installed:

> sudo apt-get upgrade

Installation

Now you can install new packages, e.g. the mediaplayer mplayer:

> sudo apt-get install mplayer

Removal

If you would like to remove software, you have different options what to remove:
Remove only the package, but not configuration or package data. Also does not remove dependencies:

> sudo apt-get remove packagename
Remove package, configuration and package data. Does not remove dependencies:

> sudo apt-get purge packagename
Remove orphaned packages, i.e. packages that were installed as dependencies but are no longer used:

> sudo apt-get autoremove

Synaptic - a GUI for aptitude

If you run Raspbian with a window manager, you can install Synaptic, which is a graphical user interface to aptitude. With Synaptic you can search, install, remove and manage your packages in a nice graphical utility. Install with

> sudo apt-get install synaptic
Launch it from the Preferences menu.


Useful software

usbmount

Data like media files that are stored on a USB device can be changed in the most convenient way. Many projects thus benefit from data on a USB device, which have to be mounted manually.The usbmount utility mounts a USB device automatically to /media/usb. Install the usbmount package with the following command.

> sudo apt-get install usbmount

Fix for Raspbian Stretch
On Raspbian Stretch, you need to fix an issue with filesystem namespaces:
Create a directory and file /etc/systemd/system/systemd-udevd.service.d/myoverride.conf and edit the content of the file to contain

[Service]
MountFlags=shared
Then restart the systemd-udevd service by running the command

> sudo service systemd-udevd restart
The original post of this fix can be found here:
https://unix.stackexchange.com/questions/330094/udev-rule-to-mount-disk-does-not-work/330156#330156

git

git is a revision control system. A revision control system tracks changes in files, usually source code files. You will often use it to download code, mostly from https://github.com. If you get more into coding, you should look into git further, as it helps you managing your changes. No more copying, renaming and accidently overwriting files ;)

> sudo apt-get install git

omxplayer

omplayer is a commandline media player developed for Raspberry Pi. It uses hardware acceleration and is the most performant player on Raspberry Pi. Use this player when possible for simple video or audio projects.

> sudo apt-get install omxplayer

mplayer

mplayer is a commandline media player. Performance on Raspberry Pi does not match omxplayer, but allows more control and more formats. Use this player if you need more control in your video or audio project.

> sudo apt-get install mplayer

Adafruit's video looper

Adafruit's video looper is the way to go if you need a device that simply loops one or more videos.
It is not a package that you can install with aptitude. You need to download a install script that installs dependencies and the video looper software.

Please follow the instructions on Adafruit's website:
https://learn.adafruit.com/raspberry-pi-video-looper/overview

If you have your Raspbian already up and running, you can jump to the install command section:
https://learn.adafruit.com/raspberry-pi-video-looper/installation#install-commands-2-11


GPIO

The Raspberry Pi has two rows of GPIO (General Purpose Input and Output) pins. These pins can be used to attach buttons, LEDs or other electro-/mechanical parts and sensors. Using GPIO the Raspberry Pi can interface its environment. You can build custom user interfaces for your audience or measure the state of its surroundings using elaborate sensory.

Pinout

The GPIO pins provide bi-directional digital input and output, PWM, I2C, SPI and UART as well as some power and ground pins.
The pinout image below is from Element14, one of the Raspberry Pi manufacturers, and shows both pinouts for early early models with 26 pins and latest models with 40 pins. The upper pins correspond to the pins in the corner of your Raspberry Pi board. The image was found on Sparkfun's website, which is well worth a visit as it provides more detailed information:
https://learn.sparkfun.com/tutorials/raspberry-gpio/gpio-pinout

The logic voltage is 3.3V! Do not apply voltages > 3.3V to the GPIO pins, e.g. from the 5V power pin or microcontroller boards like Arduino.

How to use GPIO in Python

Raspbian comes preinstalled with Python and the Python module RPi.GPIO, which provides functions to use GPIO.
Here is a summary of RPi.GPIO functions:

# import GPIO module
import RPi.GPIO as GPIO


# set pin numbering mode:
# GPIO.BOARD: Use consecutive pin numbering
#             = the number in the Pin# column in the pinout image
# GPIO.BCM:   Use numbering used by the Broadcomm chip
#             = the number in GPIO** in the NAME column of the pinout image

GPIO.setmode(GPIO.BOARD)


# set pin mode to output, input, input with pullup/-down resistor
GPIO.setup(11, GPIO.OUT)
GPIO.setup(13, GPIO.IN)
GPIO.setup(19, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

# set output value
GPIO.output(11, GPIO.LOW)
GPIO.output(11, GPIO.HIGH)

# read input value
if GPIO.input(13):
    print("Pin 13 is HIGH")
else:
    print("Pin 13 is LOW")


# setup PWM with frequency of 1000Hz
# only pin 12/18 (BOARD/BCM number) is capable of PWM
pwm = GPIO.PWM(12, 1000)

# start PWM with 50% duty cycle
pwm.start(50)

# change duty cycle to 75%
pwm.ChangeDutyCycle(75)


# free GPIO resources after you are done
# for other processes to use GPIO
GPIO.cleanup()
For detailed information, please visit the great tutorials on Sparkfun's website, where the summary was derived from:
https://learn.sparkfun.com/tutorials/raspberry-gpio/python-rpigpio-api

Autorunning a program

Often you would like to run a program at the end of your Raspberry Pi's boot process. This is especially useful for exhibitions, where your system is shut down at night an powered again the next day. You have several options to run scripts automatically.

Autorun after boot

To run a script or command after boot, edit the file /etc/rc.local.

> sudo nano /etc/rc.local
Then add your command to the end of the file before the exit command.

Note the & symbol after the command. Appending this symbol will make the command run in background and control is returned to the user immediately. If you don't run the command in background, control is returned not before the command has finished. This means that the boot process is blocked and you may not be able to log into your Pi locally. Which may not necessarily be a problem. Be aware of this behavior and use the & symbol when possible while developing.

Autorun on logging in to a terminal

You can run a command, when you log in to a terminal by editing the hidden file .bashrc in a user's home directory, in our case the user pi. The procedure is equivalent to editing rc.local for autorun after boot.

> nano ~/.bashrc
You log in to a terminal when you log in locally to a headless Raspbian version, remotely via SSH or when you open a terminal in your window manager.

Autorun on logging in to a desktop

You can run a command, when you log in to a desktop by editing the hidden file .Desktop in a user's home directory, in our case the user pi. The procedure is equivalent to editing rc.local for autorun after boot.

> nano ~/.Desktop


Configuring audio output from commandline

You can control the audio output of your Raspberry Pi from commandline, e.g. previous to running a program after boot where you would add the following commands to the /etc/rc.local file.

Configure output device

Set HDMI as output device:

> amixer cset numid=3 2

Set headphone jack as output device:

> amixer cset numid=3 1

Set automatic selection (default):

> amixer cset numid=3 0

You can also set the audio output device using

> sudo raspi-config

Configure volume

Set audio device volume:

> amixer set PCM 99%