Installing the library

You can install the library in a few different ways.

Building and installing the library from source code is preferable since it will include all the latest changes.
Installing the library (via a package manager) from a pre-built package is mostly for cross-compiling purposes, but it can be useful for environments that don't have all the build-time dependencies (namely CMake).

Warning: If you have previously installed the library from source code using the the older instructions, then you will need to uninstall it manually to avoid runtime conflicts.
sudo rm /usr/local/lib/librf24.*

sudo rm /usr/local/lib/librf24-bcm.so

sudo rm -r /usr/local/include/RF24

The librf24-bcm.so file may not exist if you used CMake to install the library.

Automatic Installation

There is a newer automatic install script that makes use of the CMake approach.

Download the install.sh file from https://github.com/nRF24/.github/blob/main/installer/install.sh
wget https://raw.githubusercontent.com/nRF24/.github/main/installer/install.sh
Make it executable
chmod +x install.sh
Run it and choose your options
./install.sh

Warning
SPIDEV is now always selected as the default driver because all other Linux drivers are being removed in the future. See RF24 issue #971 for rationale.

It will also ask to install a python package named pyRF24. This is not the same as the traditionally provided python wrappers as the pyRF24 package can be used independent of the C++ installed libraries. For more information on this newer python package, please check out the pyRF24 documentation.
Try an example from one of the libraries
cd ~/rf24libs/RF24/examples_linux

Edit the gettingstarted example, to set your pin configuration
nano gettingstarted.cpp

Build the examples. Remember to set the RF24_DRIVER option according to the one that was selected during the scripted install.
mkdir build && cd build

cmake .. -D RF24_DRIVER=SPIDEV

make

Run the example
sudo ./gettingstarted

Building from source code

Install prerequisites if there are any (PiGPIO, WiringPi, MRAA, LittleWire libraries, and enable the SPI bus(es) in the OS).

CMake may need to be installed
sudo apt-get install cmake

Note
See the MRAA documentation for more information on installing MRAA.
Make a directory to contain the RF24 library and possibly other RF24* libraries and enter it
mkdir ~/rf24libs

cd ~/rf24libs
Clone the RF24 repo and navigate to it
git clone https://github.com/nRF24/RF24.git RF24

cd RF24
Create a build directory inside the RF24 directory and navigate to it.
mkdir build

cd build
Configure build environment

Note
When using these instructions to install RF24Mesh, RF24Network, or RF24Gateway, the following RF24_DRIVER option is only needed for the RF24 library and examples as well as the examples for RF24Network, RF24Mesh, and RF24Gateway. The RF24_DRIVER option is not needed when installing the libraries for RF24Network, RF24Mesh, and RF24Gateway.

Instead of specifying the RF24_DRIVER option in the CLI, it is recommended to use a environment variable named RF24_DRIVER.

export RF24_DRIVER=SPIDEV

These instructions assume you have not set an environment variable.

cmake .. -D RF24_DRIVER=SPIDEV

Instead of using SPIDEV driver (recommended), you can also specify the RPi, wiringPi, MRAA, or LittleWire as alternative drivers.

Warning
SPIDEV is now always selected as the default driver because all other Linux drivers are being removed in the future. See RF24 issue #971 for rationale.
Build and install the library
make

sudo make install
Build the examples

Navigate to the examples_linux directory
cd ../examples_linux

Make sure the pins used in the examples match the pins you used to connect the radio module
nano gettingstarted.cpp

and edit the pin numbers as directed in the linux/RPi general documentation. Create a build directory in the examples_linux directory and navigate to it.
mkdir build

cd build

Now you are ready to build the examples.
cmake ..

make

If using the MRAA or wiringPi drivers, then you may need to specify the RF24_DRIVER option again.
cmake .. -D RF24_DRIVER=wiringPi

make

Remember that the RF24_DRIVER option is needed for the RF24Network, RF24Mesh, and RF24Gateway examples if you specified that option (via CLI or environment variable) when installing the RF24 library and examples.
Run an example file
sudo ./gettingstarted

Using a package manager

The RF24 library now (as of v1.4.1) has pre-built packages (.deb or .rpm files) that can be installed on a Raspberry Pi. These packages can be found on the library's GitHub release page

Download the appropriate package for your machine

Go to the library's GitHub release page, and look for the latest release's assets.

For all Raspberry Pi variants using the Raspberry Pi OS (aka Raspbian), you need the file marked for armhf architecture.

For Raspberry Pi variants using a 64-bit OS (like Ubuntu), you need the file marked for arm64 architecture.

Notice that the filenames will include the name of the utility driver that the package was built with. This does not mean that the LittleWire, MRAA, or wiringPi libraries are included in the package (you will still need to install those yourself beforehand).
Install the downloaded pkg

If you downloaded the file directly from your target machine using the desktop environment, then you only need to double-click the package (deb or rpm) file, and the OS should do the rest.

If you downloaded the file remotely and want to copy it over ssh, then use the scp command in a terminal.
scp pkg_filename.deb pi@host_name:~/Downloads

Note
You do not need to do this from within an ssh session. Also, you can use the target machine's IP address instead of its host name.

The scp command will ask you for a password belonging to the user's name on the remote machine (we used pi in the above example).

Now you can open up a ssh session and install the copied package from the terminal.
ssh pi@host_name

cd Downloads

dpkg -i pkg_filename.deb

Cross-compiling the library

The RF24 library comes with some pre-made toolchain files (located in the RF24/cmake/toolchains directory) to use in CMake. To use these toolchain files, additional command line options are needed when configuring CMake to build the library (step 5 in the above instructions to build from source).

cmake .. -D CMAKE_TOOLCHAIN_FILE=cmake/toolchains/armhf.cmake

make

If you plan on using the cross-compiled library with your personal cross-compiled project, then it is advised to specify the path that your project will look in when linking to the RF24 library:

cmake .. -D CMAKE_INSTALL_PREFIX=/usr/arm-linux-gnueabihf -D CMAKE_TOOLCHAIN_FILE=cmake/toolchains/armhf.cmake
make
sudo make install

Remember to also specify the RF24_DRIVER option (via CLI or environment variable) if not using the auto-configuration feature (see step 5 in the above instructions to build from source).