# extcheck(1) - man - phpman

[extcheck(1)](https://www.chedong.com/phpMan.php/man/extcheck/1/markdown)                                  Basic Tools                                 [extcheck(1)](https://www.chedong.com/phpMan.php/man/extcheck/1/markdown)



## NAME
       extcheck - Detects version conflicts between a target Java Archive (JAR) file and currently
       installed extension JAR files.

## SYNOPSIS
       **extcheck** [_options_] _targetfile.jar_


       _options_
              The command-line options. See Options.

       _targetfile.jar_
              The target JAR file against which the currently installed extension JAR files are
              compared to detect version conflicts.

## DESCRIPTION
       The **extcheck** command checks a specified JAR file for title and version conflicts with any
       extensions installed in the Java SE SDK. Before installing an extension, you can use this
       utility to see whether the same or a more recent version of the extension is already
       installed.

       The **extcheck** command compares the Specification-title and Specification-version headers in
       the manifest of the **targetfile.jar** file against the corresponding headers in all JAR files
       currently installed in the extension directory. By default, the extension directory is
       **jre/lib/ext** on Oracle Solaris and **\jre\lib\ext** on Windows. The **extcheck** command compares
       version numbers in the same way as the **java.lang.Package.isCompatibleWith** method.

       If no conflict is detected, then 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, then a non-zero error code is returned.
       A non-zero error code is also returned when **targetfile.jar** does not have the **Specification-**
       **title** or **Specification-version** attributes in its manifest file.

## OPTIONS
### -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_
              Passes _option_ to the Java Virtual Machine (JVM), where option is one of the options
              described on the reference page for the Java launcher. For example, **-J-Xms48m** sets the
              startup memory to 48 MB. See [java(1)](https://www.chedong.com/phpMan.php/man/java/1/markdown).

## SEE ALSO
       • [jar(1)](https://www.chedong.com/phpMan.php/man/jar/1/markdown)



JDK 8                                     21 November 2013                               [extcheck(1)](https://www.chedong.com/phpMan.php/man/extcheck/1/markdown)