The jlink Command

Name

jlink - assemble and optimize a set of modules and their dependencies into a custom runtime image

Synopsis

jlink [options] --module-path modulepath --add-modules module[,module...]

options: Command-line options separated by spaces. See jlink Options.
modulepath: The path where the jlink tool discovers observable modules. These modules can be modular JAR files, JMOD files, or exploded modules.
module: The names of the modules to add to the runtime image. The jlink tool adds these modules and their transitive dependencies.

Description

The jlink tool links a set of modules, along with their transitive dependences, to create a custom runtime image.

Note:

Developers are responsible for updating their custom runtime images.

jlink Options

--add-modules mod[,mod...]

Adds the named modules, mod, to the default set of root modules. The default set of root modules is empty.

--bind-services

Link service provider modules and their dependencies.

-c zip-{0-9} or --compress=zip-{0-9}

Enable compression of resources. The accepted values are: zip-{0-9}, where zip-0 provides no compression, and zip-9 provides the best compression. Default is zip-6.

Deprecated values to be removed in a future release:

0: No compression. Use zip-0 instead.
1: Constant string sharing
2: ZIP. Use zip-6 instead.

--disable-plugin pluginname

Disables the specified plug-in. See jlink Plug-ins for the list of supported plug-ins.

--endian {little|big}

Specifies the byte order of the generated image. The default value is the format of your system's architecture.

-h or --help

Prints the help message.

--ignore-signing-information

Suppresses a fatal error when signed modular JARs are linked in the runtime image. The signature-related files of the signed modular JARs aren't copied to the runtime image.

--launcher command=module or --launcher command=module/main

Specifies the launcher command name for the module or the command name for the module and main class (the module and the main class names are separated by a slash (/)).

--limit-modules mod[,mod...]

Limits the universe of observable modules to those in the transitive closure of the named modules, mod, plus the main module, if any, plus any further modules specified in the --add-modules option.

--list-plugins

Lists available plug-ins, which you can access through command-line options; see jlink Plug-ins.

-p or --module-path modulepath

A ":"-separated list of elements (";" on Windows), each of which is a file path to a module or a directory containing modules. Each module is either a modular JAR file, a JMOD file, or an exploded-module directory. If the specified module path does not contain java.base, it is prepended to the default module path. The default module path contains the standard and JDK modules provided by the JDK running jlink. This allows jlink to find java.base and other modules without specifying their locations to the --module-path option. If the --module-path option is not specified, then only the default module path is used. When creating a run-time image for a different target platform (cross-linking), the specified module path must contain all modules required for the target platform, including java.base.

--no-header-files

Excludes header files.

--no-man-pages

Excludes man pages.

--output path

Specifies the location of the generated runtime image.

--save-opts filename

Saves jlink options in the specified file.

--suggest-providers [name, ...]

Suggest providers that implement the given service types from the module path.

--version

Prints version information.

@filename

Reads options from the specified file. An options file is a text file that contains the options and values that you would typically enter in a command prompt. Options may appear on one line or on several lines. You may not specify environment variables for path names. You may comment out lines by prefixing a hash symbol (#) to the beginning of the line. The following is an example of an options file for the jlink command:

#Wed Dec 07 00:40:19 EST 2016
--module-path mlib
--add-modules com.greetings
--output greetingsapp

jlink Plug-ins

Note:

Plug-ins not listed in this section aren't supported and are subject to change.

For plug-in options that require a pattern-list, the value is a comma-separated list of elements, with each element using one the following forms:

glob-pattern
glob:glob-pattern
regex:regex-pattern
@filename
- filename is the name of a file that contains patterns to be used, one pattern per line.

For a complete list of all available plug-ins, run the command jlink --list-plugins.

Plugin `compress`

Options

--compress=zip-{0-9}[:filter=pattern-list]

Description

Compresses all resources in the output image. Accepted values are: zip-{0-9}, where zip-0 provides no compression, and zip-9 provides the best compression. Default is zip-6.

Deprecated values to be removed in a future release:

Level 0: No compression. Use zip-0 instead.
Level 1: Constant string sharing
Level 2: ZIP. Use zip-6 instead.

An optional pattern-list filter can be specified to list the pattern of files to include.

Plugin `include-locales`

Options: --include-locales=langtag[,langtag]*
Description: Includes the list of locales where langtag is a BCP 47 language tag. This option supports locale matching as defined in RFC 4647. Ensure that you add the module jdk.localedata when using this option. Example:

--add-modules jdk.localedata --include-locales=en,ja,*-IN

Plugin `order-resources`

Options: --order-resources=pattern-list
Description: Orders the specified paths in priority order. If @filename is specified, then each line in pattern-list must be an exact match for the paths to be ordered. Example:

--order-resources=/module-info.class,@classlist,/java.base/java/lang/

Plugin `strip-debug`

Options: --strip-debug
Description: Strips debug information from the output image. Source-file names, source-debug extensions, line numbers, and local-variable information are removed from class files. Consequently, stack traces for affected classes omit source-file names and line numbers, and debuggers lose source-line and local-variable information. On supported platforms, native debug symbols are also stripped. External debug-symbol files and directories, such as .pdb, .map, .dSYM, .debuginfo, and .diz, are excluded from the output image.

Plugin `generate-cds-archive`

Options: --generate-cds-archive
Description: Generate CDS archive if the runtime image supports the CDS feature.

Plugin `cacerts`

Options: --cacerts=alias[,alias]*
Description: Create the cacerts keystore in the output image with only the certificates of the specified aliases. alias is the name of an alias in the cacerts keystore in the java.base module.

jlink Examples

The following command creates a runtime image in the directory greetingsapp. This command links the module com.greetings, whose module definition is contained in the directory mlib.

jlink --module-path mlib --add-modules com.greetings --output greetingsapp

The following command lists the modules in the runtime image greetingsapp:

greetingsapp/bin/java --list-modules
com.greetings
java.base@11
java.logging@11
org.astro@1.0

The following command creates a runtime image in the directory compressedrt that's stripped of debug symbols, uses compression to reduce space, and includes French language locale information:

jlink --add-modules jdk.localedata --strip-debug --compress=2 --include-locales=fr --output compressedrt

The following example compares the size of the runtime image compressedrt with fr_rt, which isn't stripped of debug symbols and doesn't use compression:

jlink --add-modules jdk.localedata --include-locales=fr --output fr_rt

du -sh ./compressedrt ./fr_rt
23M     ./compressedrt
36M     ./fr_rt

The following example lists the providers that implement java.security.Provider:

jlink --suggest-providers java.security.Provider

Suggested providers:
  java.naming provides java.security.Provider used by java.base
  java.security.jgss provides java.security.Provider used by java.base
  java.security.sasl provides java.security.Provider used by java.base
  java.smartcardio provides java.security.Provider used by java.base
  java.xml.crypto provides java.security.Provider used by java.base
  jdk.crypto.cryptoki provides java.security.Provider used by java.base
  jdk.security.jgss provides java.security.Provider used by java.base

The following example creates a custom runtime image named mybuild that includes only java.naming and jdk.crypto.cryptoki and their dependencies but no other providers. Note that these dependencies must exist in the module path:

jlink --add-modules java.naming,jdk.crypto.cryptoki --output mybuild

The following command is similar to the one that creates a runtime image named greetingsapp, except that it will link the modules resolved from root modules with service binding; see the Configuration.resolveAndBind method.

jlink --module-path mlib --add-modules com.greetings --output greetingsapp --bind-services

The following command lists the modules in the runtime image greetingsapp created by this command:

greetingsapp/bin/java --list-modules
com.greetings
java.base@11
java.compiler@11
java.datatransfer@11
java.desktop@11
java.logging@11
java.management@11
java.management.rmi@11
java.naming@11
java.prefs@11
java.rmi@11
java.security.jgss@11
java.security.sasl@11
java.smartcardio@11
java.xml@11
java.xml.crypto@11
jdk.accessibility@11
jdk.charsets@11
jdk.compiler@11
jdk.crypto.cryptoki@11
jdk.crypto.ec@11
jdk.crypto.mscapi@11
jdk.internal.opt@11
jdk.jartool@11
jdk.javadoc@11
jdk.jdeps@11
jdk.jfr@11
jdk.jlink@11
jdk.localedata@11
jdk.management@11
jdk.management.jfr@11
jdk.naming.dns@11
jdk.naming.rmi@11
jdk.security.auth@11
jdk.security.jgss@11
jdk.zipfs@11
org.astro@1.0

Name

Synopsis

Description

jlink Options

jlink Plug-ins

Plugin compress

Plugin include-locales

Plugin order-resources

Plugin strip-debug

Plugin generate-cds-archive

Plugin cacerts