How to fix 'command not found: pio' even though PlatformIO is installed

Problem:

You have installed PlatformIO on your computer using Visual Studio code, however when you try to run it in your terminal/shell, you see:

$ pio
zsh: command not found: pio

Solution

PlatformIO is installed in $HOME/.platformio, but not added to the PATH environment variable, so your terminal can’t find it. Add it using

echo "export PATH=\$PATH:/home/${USER}/.platformio/penv/bin" >> ~/.profile

and then logout from your current session and log back in again (or reboot) in order for the changes to take effect. After that, you can run pio from any shell.