escpos-cli is a command-line utility for printing stuff using pyxmlescpos
pip2 install -U git+https://github.com/kalmanolah/escpos-cli.git
From the command line:
$ escpos-cli --device-vendor-id 0x04b8 --device-product-id 0x0e15 '<receipt><h1 align="center">Test Receipt!</h1><line/></receipt>'
This utility depends on pyxmlescpos. Currently, my fork located here is used since it adds additional support for QR codes.