APT keeps a list of software sources on your Raspberry Pi in a file at /etc/apt/sources.list. Before installing software, you should update your package list with apt update. Go ahead and open a Terminal window and type:

Next, upgrade all your installed packages to their latest versions with the following command:

Note that full-upgrade is used in preference to a simple upgrade, as it also picks up any dependency changes that may have been made.

Generally speaking, doing this regularly will keep your installation up to date for the particular major Raspberry Pi OS release you are using (e.g. Buster). It will not update from one major release to another, for example, Stretch to Buster or Buster to Bullseye.

However, there are occasional changes made in the Raspberry Pi OS image that require manual intervention, for example a newly introduced package. These are not installed with an upgrade, as this command only updates the packages you already have installed.

If moving an existing SD card to a new Raspberry Pi model (for example the Raspberry Pi Zero 2 W), you may also need to update the kernel and the firmware first using the instructions above.

When running sudo apt full-upgrade, it will show how much data will be downloaded and how much space it will take up on the SD card. It’s worth checking with df -h that you have enough free disk space, as unfortunately apt will not do this for you. Also be aware that downloaded package files (.deb files) are kept in /var/cache/apt/archives. You can remove these in order to free up space with sudo apt clean (sudo apt-get clean in older releases of apt).

The latest version of Raspberry Pi OS is based on Debian Bullseye. The previous version was based on Buster. If you want to perform an in-place upgrade from Buster to Bullseye (and you’re aware of the risks) see the instructions in the forums.

You can search the archives for a package with a given keyword with apt-cache search:

You can view more information about a package before installing it with apt-cache show:

Typing this command should inform the user how much disk space the package will take up and asks for confirmation of the package installation. Entering Y (or just pressing Enter, as yes is the default action) will allow the installation to occur. This can be bypassed by adding the -y flag to the command:

Installing this package makes tree available for the user.

You can uninstall a package with apt remove:

The user is prompted to confirm the removal. Again, the -y flag will auto-confirm.

You can also choose to completely remove the package and its associated configuration files with apt purge:

rpi-update will download the latest pre-release version of the linux kernel, its matching modules, device tree files, along with the latest versions of the VideoCore firmware. It will then install these files to relevant locations on the SD card, overwriting any previous versions.

All the source data used by rpi-update comes from the rpi-firmware repository. This repository simply contains a subset of the data from the official firmware repository, as not all the data from that repo is required.

If you are sure that you need to use rpi-update, it is advisable to take a backup of your current system first as running rpi-update could result in a non-booting system.

rpi-update needs to be run as root. Once the update is complete you will need to reboot.

It has a number of options documented in the rpi-update repository.

If you have done an rpi-update and things are not working as you wish, if your Raspberry Pi is still bootable you can return to the stable release using:

You will need to reboot your Raspberry Pi for these changes to take effect.

A video sample of the animated film Big Buck Bunny is available on your Raspberry Pi. To play it enter the following command into a terminal window:

On a Raspberry Pi 4, use the following command for H264 files:

or for H264, VC1, or MPEG2

When using VLC, you can improve playback performance by encapsulating the raw H264 stream, for example from the Raspberry Pi Camera Module. This is easily done using ffmpeg. Playback is also improved if VLC is run full screen; either select fullscreen from the user interface, or you can add the --fullscreen options to the vlc command line.

This example command converts video.h264 to a containerised video.mp4 at 30 fps:

ffmpeg -r 30 -i video.h264 -c:v copy video.mp4

Now add the --no-banner flag:

which shows the following information:

Now the picture is taken at full resolution with no banner.

Power on the HDMI output with preferred settings.

Powers off the display output.

A better option is to use the vcgencmd display_power option, as this will retain any framebuffers, so when the power is turned back on the display will be the returned to the previous power on state.

Power on the HDMI with the specified settings

Group can be one of CEA, DMT, CEA_3D_SBS, CEA_3D_TB, CEA_3D_FP, CEA_3D_FS.
Mode is one of the modes returned from the -m, --modes option.
Drive can be one of HDMI, DVI.

Use 59.94Hz (NTSC frequency) rather than 60Hz for HDMI mode.

Power on the SDTV (composite output) with the specified mode, PAL or NTSC, and the specified aspect, 4:3, 14:9, 16:9. The optional P parameter can be used to specify progressive mode.

where Group is CEA or DMT.

Shows a list of display modes available in the specified group.

Monitors for any HDMI events, for example unplugging or attaching.

Shows the current settings for the display mode, including mode, resolution, and frequency.

Shows the current settings for the audio mode, including channels, sample rate and sample size.

Save the current EDID to the specified filename. You can then use edidparser <filename> to display the data in a human readable form.

When used in combination with the --modes options, displays the mode information in JSON format.

Extracts the display name from the EDID data and shows it.

Lists all attached displays and their display ID.

Specifies the ID of the device to use; see the output of --list for available IDs.

The vcos command has two useful sub-commands:

Displays the build date and version of the VideoCore firmware.

Displays the enabled and detected state of the Raspberry Pi camera: 1 means yes, 0 means no. Whilst all firmware except cutdown versions support the camera, this support needs to be enabled by using raspi-config.

Returns the throttled state of the system. This is a bit-pattern - a bit being set indicates the following meanings:

Returns the temperature of the SoC as measured by its internal temperature sensor; on Raspberry Pi 4, measure_temp pmic returns the temperature of the PMIC.

This returns the current frequency of the specified clock. The options are:

e.g. vcgencmd measure_clock arm

Displays the current voltages used by the specific block.

Displays the content of the OTP (one-time programmable) memory inside the SoC. These are 32-bit values, indexed from 8 to 64. See the OTP bits page for more details.

Display value of the configuration setting specified: alternatively, specify either int (integer) or str (string) to see all configuration items of the given type. For example:

returns the total memory on the device in megabytes.

Reports on the amount of memory addressable by the ARM and the GPU. To show the amount of ARM-addressable memory use vcgencmd get_mem arm; to show the amount of GPU-addressable memory use vcgencmd get_mem gpu. Note that on devices with more than 1GB of memory the arm parameter will always return 1GB minus the gpu memory value, since the GPU firmware is only aware of the first 1GB of memory. To get an accurate report of the total memory on the device, see the total_mem configuration item - see get_config section above.

Shows various items of version information from the VideoCore.

Dumps logs from the specified subsystem. Possible options are:

e.g. To print out the current contents of the message log:

vcdbg log msg

List all memory allocations current in the VideoCore heap.

List the current status of the pool allocator

Without any further parameters, lists the current status of the relocatable allocator. Use sudo vcdbg reloc small to list small allocations as well.

Use the subcommand sudo vcdbg reloc stats to list statistics for the relocatable allocator.

Commands related to task history.

Use sudo vcdbg hist gnuplot to dump task history in gnuplot format to task.gpt and task.dat

Some languages use curly braces { and } to wrap around lines of code which belong together, and leave it to the writer to indent these lines to appear visually nested. However, Python does not use curly braces but instead requires indentation for nesting. For example a for loop in Python:

The indentation is necessary here. A second line indented would be a part of the loop, and a second line not indented would be outside of the loop. For example:

would print:

whereas the following:

would print:

To save a value to a variable, assign it like so:

Note that data types were not specified with these variables, as types are inferred, and can be changed later.

This time I used comments beside the increment command.

Comments are ignored in the program but there for you to leave notes, and are denoted by the hash # symbol. Multi-line comments use triple quotes like so:

Python also has lists (called arrays in some languages) which are collections of data of any type:

Lists are denoted by the use of square brackets [] and each item is separated by a comma.

Some data types are iterable, which means you can loop over the values they contain. For example a list:

This takes each item in the list numbers and prints out the item:

Note I used the word number to denote each item. This is merely the word I chose for this - it’s recommended you choose descriptive words for variables - using plurals for lists, and singular for each item makes sense. It makes it easier to understand when reading.

Other data types are iterable, for example the string:

This loops over each character and prints them out:

The integer data type is not iterable and trying to iterate over it will produce an error. For example:

will produce:

However you can make an iterable object using the range function:

range(5) contains the numbers 0, 1, 2, 3 and 4 (five numbers in total). To get the numbers 1 to 5 (inclusive) use range(1, 6).

You can use functions like len to find the length of a string or a list:

You can use if statements for control flow:

IPython is an interactive Python shell with syntax highlighting, autocompletion, pretty printing, built-in documentation, and more. IPython is not installed by default. Install with:

Then run with ipython from the command line. It works like the standard python3, but has more features. Try typing len? and hitting Enter. You’re shown information including the docstring for the len function:

Try the following dictionary comprehension:

This will pretty print the following:

In the standard Python shell, this would have printed on one line:

You can look back on the history of the commands you’ve entered in the REPL by using the Up/Down keys like in python. The history also persists to the next session, so you can exit ipython and return (or switch between v2/3) and the history remains. Use Ctrl + D to exit.

Some Python packages can be found in the Raspberry Pi OS archives, and can be installed using apt, for example:

This is a preferable method of installing, as it means that the modules you install can be kept up to date easily with the usual sudo apt update and sudo apt full-upgrade commands.

Not all Python packages are available in the Raspberry Pi OS archives, and those that are can sometimes be out of date. If you can’t find a suitable version in the Raspberry Pi OS archives, you can install packages from the Python Package Index (known as PyPI).

To do so, install pip:

Then install Python packages (e.g. simplejson) with pip3:

To control an LED connected to GPIO17, you can use this code:

Run this in an IDE like Thonny, and the LED will blink on and off repeatedly.

LED methods include on(), off(), toggle(), and blink().

To read the state of a button connected to GPIO2, you can use this code:

Button functionality includes the properties is_pressed and is_held; callbacks when_pressed, when_released, and when_held; and methods wait_for_press() and wait_for_release.

To connect the LED and button together, you can use this code:

Alternatively:

or: