9.1.1.4. Java archives

The GNU project provides us with the jar tool for creating Java archives. It is a Java application that combines multiple files into a single JAR archive file. While also being a general purpose archiving and compression tool, based on ZIP and the ZLIB compression format, jar was mainly designed to facilitate the packing of Java code, applets and/or applications in a single file. When combined in a single archive, the components of a Java application, can be downloaded much faster.

Unlike tar, jar compresses by default, independent from other tools - because it is basically the Java version of zip. In addition, it allows individual entries in an archive to be signed by the author, so that origins can be authenticated.

The syntax is almost identical as for the tar command, we refer to info jar for specific differences.

	tar, jar and symbolic links
	One noteworthy feature not really mentioned in the standard documentation is that jar will follow symbolic links. Data to which these links are pointing will be included in the archive. The default in tar is to only backup the symbolic link, but this behavior can be changed using the -h to tar.