Add to PATH for every login

Total control version:

in your terminal, navigate to home directory

cd

create file .bash_profile

touch .bash_profile

open file with TextEdit

open -e .bash_profile

insert line into TextEdit

export PATH=$PATH:/Users/username/Library/Android/sdk/platform-tools/

save file and reload file

source ~/.bash_profile

check if adb was set into path

adb version

One liner version

Echo your export command and redirect the output to be appended to .bash_profile file and restart terminal. (have not verified this but should work)

echo "export PATH=$PATH:/Users/username/Library/Android/sdk/platform-tools/ sdk/platform-tools/" >> ~/.bash_profile

Alternative: Install adb the easy way

If you don't want to have to worry about your path or updating adb manually, you can use homebrew instead.

brew cask install android-platform-tools

Why are you trying to run "./adb"? That skips the path variable entirely and only looks for "adb" in the current directory. Try running "adb" instead.

Edit: your path looks wrong. You say you get

/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/Libs/android-sdk-mac_x86/tools:/Libs/android-sdk-mac_x86/platform-tools

You're missing the /Users/simon part.

Also note that if you have both .profile and .bash_profile files, only the latter gets executed.