Here is the reference javaworld.com/
My favorite commands are:
// listing all files
jar tvf "fileJAR/EAR"
//updating a file in a JAR/EAR file
jar uvf "fileJAR/EAR" path/to/file/to/update
//extracting a file from a JAR/EAR/WAR file
jar xvf "fileJAR/EAR" path/to/file/to/extract
