image-usb-stick is a command line tool that safely images USB devices

It supports OS X and Linux currently. Without options, the tool runs in an
interactive mode. The tool will also only allow imaging of actual external
USB storage devices, preventing accidental data loss on internal devices,
a problem often encountered when using lower level tools like dd.

The tool will also offer to unmount any mounted partitions on the target
device.

During the imaging process, useful feedback is presented to the user:

  - Percentage complete
  - Elapsed time
  - A visual progress bar
  - Estimated time remaining