The Java Archive Tool

Sun Microsystems, Inc.
Typical usage to combine files into a jar file is:
C:\Java> jar cf myFile.jar *.class

If you have a pre-existing manifest file whose name: value pairs you want the jar tool to include for the new jar archive, you can specify it using the m option:
C:\Java> jar cmf myManifestFile myFile.jar *.class

To extract the files from a jar file, use x, as in:
C:\Java> jar xf myFile.jar
To extract only certain files from a jar file, supply their filenames:
C:\Java> jar xf myFile.jar foo bar

Updates an existing file jarfile (when f is specified) by adding to it files and directories specified by inputfiles. For example:
jar uf foo.jar foo.class

would add the file foo.class to the existing jar file foo.jar. The u option can also update the manifest entry, as given by this example:
jar umf manifest foo.jar