If you want download a single artifact from the command line use Maven's dependency plug-in:
It will download the .jar file to the directory specified in -Ddest
This is awesome! For my case to download just the war from our project:
mvn dependency:get -DremoteRepositories=https://jitpack.io -Dartifact=com.github.inodb.cbioportal:cbioportal:v1.3.0-test-jitpack:war -Ddest=.