The workflow is an examples for the External Tools / UseCase plugin to integrate external tools. It wraps the "bc" command line calculator. Internally, it executes the following script: if [ ! -r "$1" ]; then echo "Cannot read file indicated by first argument '$1'." ; exit -1 ; fi ; if [ ! -r "$2" ];then echo "Cannot read file indicated by second argument '$1'." ; exit -1 ; fi if [ -x /usr/bin/bc ]; then ...