How can I set ENV from a path

I just installed android-sdk using Homebrew. The path is /usr/local/Caskroom/android-sdk/3859397,26.0.1. I know I can export ANDROID_HOME with that value. How can I set it dynamically using the real path of a command such as `sdkmanager'? So far, I found $ readlink /usr/local/bin/sdkmanager /usr/local/Caskroom/android-sdk/3859397,26.0.1/tools/bin/sdkmanager How can I set $ANDROID_HOME from this value? So that I have $ANDROID_HOME=/usr/local/Caskroom/android-sdk/3859397,26.0.1 ? $ dirname readlink /usr/local/bin/sdkmanager /usr/local/Caskroom/android-sdk/3859397,26.0.1/tools/bin Now how can I append ../..?