 <p><code>adb</code> is not in your <code>PATH</code>. </p> <p>Bash will first try to look for a binary called <code>adb</code> in your Path, and not in the current directory. Therefore, if you are currently in the <code>platform-tools</code> directory, just call</p> <pre><code>./adb --help </code></pre> <p>The dot is your current directory, and this tells Bash to use <code>adb</code> from there.</p> <p>Otherwise, you can add <code>platform-tools</code> to your <code>PATH</code>, by placing a line like this in your <code>~/.profile</code> or <code>~/.bash_profile</code>, then re-starting the Terminal. On Linux, you might want to modify <code>~/.bashrc</code> instead, <a href="http://www.joshstaiger.org/archives/2005/07/bash_profile_vs.html">depending on what is used</a>.</p> <pre><code>export PATH=/Users/espireinfolabs/Desktop/soft/android-sdk-mac_x86/platform-tools:$PATH </code></pre> <p>If you've installed the platform tools somewhere else, change the path accordingly. For Android Studio on OS X, for example, you'd use the following—note the double-quotes that prevent a possible space from breaking the path syntax:</p> <pre><code>export PATH="/Users/myuser/Library/Android/sdk/platform-tools":$PATH </code></pre>