title: adb push only if file doesn't exist or has changed
body: <p>For a program I am using ADB to transfer a file from the computer to mobile phone.</p>
  
  <p>Using <code>adb push</code> overwrites every existent file and thus takes ages to finish.
  <code>adb sync</code> does only push the file if it exists on the phone AND contains other data than the local version.</p>
  
  <p>Is there any midway solution? I want the file to be transferred if it doesn't exist or is changed, but not, if it is the same as on the computer. Is there a way to achieve this?</p>