Not able to access adb in OS X through Terminal, "command not found"

The problem is: adb is not in your PATH. This is where the shell looks for executables. You can check your current PATH with echo $PATH.

Bash will first try to look for a binary called adb in your Path, and not in the current directory. Therefore, if you are currently in the platform-tools directory, just call

./adb --help

The dot is your current directory, and this tells Bash to use adb from there.

But actually, you should add platform-tools to your PATH, as well as some other tools that the Android SDK comes with. This is how you do it:

1. Find out where you installed the Android SDK. This might be (where $HOME is your user's home directory) one of the following (or verify via Configure > SDK Manager in the Android Studio startup screen):

   • Linux: $HOME/Android/Sdk
   • macOS: $HOME/Library/Android/sdk

2. Find out which shell profile to edit, depending on which file is used:

   • Linux: typically $HOME/.bashrc
   • macOS: typically $HOME/.bash_profile
   • With Zsh: $HOME/.zshrc

3. Open the shell profile from step two, and at the bottom of the file, add the following lines. Make sure to replace the path with the one where you installed platform-tools if it differs:

   export ANDROID_HOME="$HOME/Android/Sdk"
   export PATH="$ANDROID_HOME/tools:$ANDROID_HOME/tools/bin:$ANDROID_HOME/platform-tools:$PATH"
   

4. Save the profile file, then, re-start the terminal or run source ~/.bashrc (or whatever you just modified).

Note that setting ANDROID_HOME is required for some third party frameworks, so it does not hurt to add it.

For zsh users. Add alias adb='/Users/$USER/Library/Android/sdk/platform-tools/adb' to .zshrc file.

Then run source ~/.zshrc command