Basic jar tool commands

To create a JAR jar -cf MyJar.jar MyClass.class

To extract the contents of a JAR jar -xf MyJar.jar

To view the contents of a JAR jar -tf MyJar.jar

To create a JAR with your own manifest jar -cmf myManifest.mf MyJar.jar MyClass.class

To create a JAR that contains all files within a directory
jar -cf MyJar.jar suncertify/db