my SDK is where i extracted my ExtJS files. ~/current/gaia/static/js/ext-5.1.1
you can generate workspace from within the folder like this: sencha generate workspace /tmp/extJSworkSpace
you can specify it's location if you are not in the folder. sencha -sdk ~/current/gaia/static/js/ext-5.1.1 generate workspace /tmp/extJSworkSpace
contents of the SDK folder looks like:
ls ~/current/gaia/static/js/ext-5.1.1 build cmd ext-bootstrap.js LICENSE overrides packages Readme.md src version.properties build.xml examples index.html licenses package.json plugins release-notes.html test welcome
if you don't specify -sdk flag and are not inside the folder, it will create the workspace still but there will be no 'ext' folder inside (not copied).