Install Newman from npm globally on your system allowing you to run it from anywhere
$ npm install -g newman
newman run collections/git.postman_collection.json --environment collections/newman-env.postman_environment.json --reporters cli,junit,html --reporter-junit-export testresults/unformatted/xmlOut.xml --reporter-html-export testresults/unformatted/htmlOut.html
For more information on newman cli, visit the site newman page