If you have a JAR file and want to print the details from MANIFEST.MF, this can be done with one command in linux, using the unzip utility. For example:

$ unzip -p /usr/share/java/hsqldb.jar META-INF/MANIFEST.MF
Manifest-Version: 1.0
Created-By: 1.7.0_03-b147 (Oracle Corporation)
Specification-Title: HSQLDB
Implementation-Title: Standard runtime
Class-Path: /usr/share/java/servlet-api-3.0.jar
Main-Class: org.hsqldb.util.SqlTool
Ant-Version: Apache Ant 1.8.2
Implementation-Vendor: buildd
Implementation-Version: private-2012/07/12-02:29:31
Specification-Version: 1.8.0.10
Specification-Vendor: The HSQLDB Development Group