The JAR command is include in some, but not all installations of Java. On a Linux system, the which command can be used to determine if the JAR command is part of your $PATH. If something like this is returned, you may need to install Java on your Linux system.

~]# which jar
/usr/bin/which: no jar in (/sbin:/bin:/usr/sbin:/usr/bin)

Let's say you have a .jar file that contains the following.

com/
com/example
com/example/foo.class

The following command will extract the jar archive.

/path/to/bin/jar –xf /path/to/example.jar

This will create the following files and directories in your present working directory.

/com/example/foo.class