title: Generating hash string for google sms retriever api - 'xxd' is not recognized as an internal or external command
body: <p>After the google's new policy regarding SMS and Call log permissions, I am trying to implement SMS retriever API for my android application.
  The tutorial seems easy but I found a problem while creating/generating hash for the same.</p>
  
  <p><b>When I type</b></p>
  
  <pre><code>keytool -alias MyAndroidKey -exportcert -keystore MyProduction.keystore | xxd -p | tr -d "[:space:]"
  </code></pre>
  
  <p>OR</p>
  
  <pre><code>keytool -exportcert -alias MyAndroidKey -keystore MyProductionKeys.keystore | xxd -p | tr -d "[:space:]" | echo -n com.example.myapp `cat` | sha256sum | tr -d "[:space:]-" | xxd -r -p | base64 | cut -c1-11
  </code></pre>
  
  <p><b>It says:</b></p>
  
  <pre><code>'xxd' is not recognized as an internal or external command,
  operable program or batch file.
  
  'tr' is not recognized as an internal or external command,
  operable program or batch file.
  </code></pre>
  
  <p>There are no clarification available on <a href="https://developers.google.com/identity/sms-retriever/verify#computing_your_apps_hash_string" rel="noreferrer">https://developers.google.com/identity/sms-retriever/verify#computing_your_apps_hash_string</a> page</p>
  
  <p>Thanks.</p>