How to Install And Update ADB And Fastboot on Linux

Type the commands below according to your distro.
Debian/Ubuntu sudo apt install android-tools-fastboot
Centos/Fedora/openSUSE sudo dnf install android-tools
ArchLinux and derivatives sudo pacman -Sy android-tools

Then run the commands below:
sudo apt install adb
sudo apt install fastboot

Adb and Fastboot are now installed. To check, run the commands below:

adb --version
fastboot --version

How to update ADB and Fastboot

Now download the latest platform-tools for Linux and unzip it. Copy all the files inside that folder. Now open your file manager as root. Now go to /usr/lib/android-sdk/platform-tools/ and paste the files here. That's it!
Now you can re-check the ADB and Fastboot version by using the previous commands.