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pack200(1) Java Deployment Tools pack200(1)

NAME
pack200 - Packages a JAR file into a compressed pack200 file for web deployment.

SYNOPSIS
pack200 [options] output-file JAR-file

Options can be in any order. The last option on the command line or in a properties file
supersedes all previously specified options.

options
The command-line options. See Options.

output-file
Name of the output file.

JAR-file
Name of the input file.

DESCRIPTION
The pack200 command is a Java application that transforms a JAR file into a compressed
pack200 file with the Java gzip compressor. The pack200 files are highly compressed files
that can be directly deployed to save bandwidth and reduce download time.

The pack200 command has several options to fine-tune and set the compression engine. The
typical usage is shown in the following example, where myarchive.pack.gz is produced with the
default pack200 command settings:

pack200 myarchive.pack.gz myarchive.jar

OPTIONS
-r, --repack
Produces a JAR file by packing and unpacking a JAR file. The resulting file can be
used as an input to the jarsigner(1) tool. The following example packs and unpacks the
myarchive.jar file:

pack200 --repack myarchive-packer.jar myarchive.jar
pack200 --repack myarchive.jar

The following example preserves the order of files in the input file.

-g, --no-gzip
Produces a pack200 file. With this option, a suitable compressor must be used, and the
target system must use a corresponding decompresser.

pack200 --no-gzip myarchive.pack myarchive.jar

-G, --strip-debug
Strips debugging attributes from the output. These include SourceFile,
LineNumberTable, LocalVariableTable and LocalVariableTypeTable. Removing these
attributes reduces the size of both downloads and installations, but reduces the
usefulness of debuggers.

--keep-file-order
Preserve the order of files in the input file. This is the default behavior.

-O, --no-keep-file-order
The packer reorders and transmits all elements. The packer can also remove JAR
directory names to reduce the download size. However, certain JAR file optimizations,
such as indexing, might not work correctly.

-Svalue , --segment-limit=value
The value is the estimated target size N (in bytes) of each archive segment. If a
single input file requires more than N bytes, then its own archive segment is
provided. As a special case, a value of -1 produces a single large segment with all
input files, while a value of 0 produces one segment for each class. Larger archive
segments result in less fragmentation and better compression, but processing them
requires more memory.

The size of each segment is estimated by counting the size of each input file to be
transmitted in the segment with the size of its name and other transmitted properties.

The default is -1, which means that the packer creates a single segment output file.
In cases where extremely large output files are generated, users are strongly
encouraged to use segmenting or break up the input file into smaller JARs.

A 10 MB JAR packed without this limit typically packs about 10 percent smaller, but
the packer might require a larger Java heap (about 10 times the segment limit).

-Evalue , --effort=value
If the value is set to a single decimal digit, then the packer uses the indicated
amount of effort in compressing the archive. Level 1 might produce somewhat larger
size and faster compression speed, while level 9 takes much longer, but can produce
better compression. The special value 0 instructs the pack200 command to copy through
the original JAR file directly with no compression. The JSR 200 standard requires any
unpacker to understand this special case as a pass-through of the entire archive.

The default is 5, to invest a modest amount of time to produce reasonable compression.

-Hvalue , --deflate-hint=value
Overrides the default, which preserves the input information, but can cause the
transmitted archive to be larger. The possible values are: true, false, or keep.

If the value is true or false, then the packer200 command sets the deflation hint
accordingly in the output archive and does not transmit the individual deflation hints
of archive elements.

The keep value preserves deflation hints observed in the input JAR. This is the
default.

-mvalue , --modification-time=value
The possible values are latest and keep.

If the value is latest, then the packer attempts to determine the latest modification
time, among all the available entries in the original archive, or the latest
modification time of all the available entries in that segment. This single value is
transmitted as part of the segment and applied to all the entries in each segment.
This can marginally decrease the transmitted size of the archive at the expense of
setting all installed files to a single date.

If the value is keep, then modification times observed in the input JAR are preserved.
This is the default.

-Pfile , --pass-file=file
Indicates that a file should be passed through bytewise with no compression. By
repeating the option, multiple files can be specified. There is no pathname
transformation, except that the system file separator is replaced by the JAR file
separator forward slash (/). The resulting file names must match exactly as strings
with their occurrences in the JAR file. If file is a directory name, then all files
under that directory are passed.

-Uaction , --unknown-attribute=action
Overrides the default behavior, which means that the class file that contains the
unknown attribute is passed through with the specified action. The possible values for
actions are error, strip, or pass.

If the value is error, then the entire pack200 command operation fails with a suitable
explanation.

If the value is strip, then the attribute is dropped. Removing the required Java
Virtual Machine (JVM) attributes can cause class loader failures.

If the value is pass, then the entire class is transmitted as though it is a resource.

-Cattribute-name=layout , --class-attribute=attribute-name=action
See next option.

-Fattribute-name=layout , --field-attribute=attribute-name=action
See next option.

-Mattribute-name=layout , --method-attribute=attribute-name=action
See next option.

-Dattribute-name=layout , --code-attribute=attribute-name=action
With the previous four options, the attribute layout can be specified for a class
entity, such as class-attribute, field-attribute, method-attribute, and code-
attribute. The attribute-name is the name of the attribute for which the layout or
action is being defined. The possible values for action are some-layout-string, error,
strip, pass.

some-layout-string: The layout language is defined in the JSR 200 specification, for
example: --class-attribute=SourceFile=RUH.

If the value is error, then the pack200 operation fails with an explanation.

If the value is strip, then the attribute is removed from the output. Removing JVM-
required attributes can cause class loader failures. For example, --class-
attribute=CompilationID=pass causes the class file that contains this attribute to be
passed through without further action by the packer.

If the value is pass, then the entire class is transmitted as though it is a resource.

-f pack.properties , --config-file=pack.properties
A configuration file, containing Java properties to initialize the packer, can be
specified on the command line.

pack200 -f pack.properties myarchive.pack.gz myarchive.jar
more pack.properties
# Generic properties for the packer.
modification.time=latest
deflate.hint=false
keep.file.order=false
# This option will cause the files bearing new attributes to
# be reported as an error rather than passed uncompressed.
unknown.attribute=error
# Change the segment limit to be unlimited.
segment.limit=-1

-v, --verbose
Outputs minimal messages. Multiple specification of this option will create more
verbose messages.

-q, --quiet
Specifies quiet operation with no messages.

-lfilename , --log-file=filename
Specifies a log file to output messages.

-?, -h, --help
Prints help information about this command.

-V, --version
Prints version information about this command.

-Joption
Passes the specified option to the Java Virtual Machine. For more information, see the
reference page for the java(1) command. For example, -J-Xms48m sets the startup memory
to 48 MB.

EXIT STATUS
The following exit values are returned: 0 for successful completion and a number greater than
0 when an error occurs.

NOTES
This command should not be confused with pack(1). The pack and pack200 commands are separate
products.

The Java SE API Specification provided with the JDK is the superseding authority, when there
are discrepancies.