The extcheck utility compares the Specification-title and Specification-version headers in the manifest of targetfile.jar file against the corresponding headers in all Jar files currently installed in the extension directory. (The extension directory is jre/lib/ext by default.) The extcheck utility compares version numbers in the same way as the method java.lang.Package.isCompatibleWith.
If no conflict is detected, the return code is 0.
If the manifest of any jar file in the extensions directory has the same Specification-title and the same or a newer Specification-version number, a non-zero error code is returned. A non-zero error code is also returned if targetfile.jar does not have the Specification-title or Specification-version attributes in its manifest.
|-verbose||Lists jar files in the extension directory as they are checked. Additionally, manifest attributes of the target jar file and any conflicting jar files are also reported.|
|-J option||Pass option to the Java virtual machine, where option is one of the options described on the man page for the java application launcher, java(1). For example, -J-Xms48m sets the startup memory to 48 megabytes.|