build.gradle in your project which generates the apk:
apply from:'https://gist.githubusercontent.com/pboos/c4ae04b62641d7e9897c/raw/45515edf3cf00925b59a51d0ca893c44a2b06851/gradle-s3-upload.gradle'
~/.gradle/gradle.properties
AWS_S3_KEY_ID=****Your Amazon Key Id****
AWS_S3_KEY_SECRET=****Your Amazon Key Secret****
gradle.properties in your project which generates the apk:
AWS_S3_APK_PREFIX=MyApp
If you are running it from a cmd terminal, try running it from git shell or cygwin.