pack200(1)pack200(1)NAMEpack200 - JAR Packing tool
SYNOPSISpack200 [ OPTIONS ] output-file JAR-file
PARAMETERS
The options may be in any order. The last option on the command line or
in a properties file supersedes all previously specified options. For a
discussion of the options, see OPTIONS below.
OPTIONS see OPTIONS below.
output-file name of the output file.
JAR-file name of the input file.
DESCRIPTION
The pack200 tool is a Java application that transforms a JAR file into
a compressed pack200 file using the Java gzip compressor. The com‐
pressed packed files are highly compressed JARs that can be directly
deployed, saving bandwidth and reducing download time.
The pack200 tool uses several options to fine-tune and set the compres‐
sion engine.
Typical usage:
% pack200 myarchive.pack.gz myarchive.jar
In this example, the myarchive.pack.gz is produced, using the default
pack200 and gzip settings.
OPTIONS
-r --repack
Produces a JAR file by packing the file myarchive.jar, and
unpacking it. The resulting file can be used as an input to the
jarsigner(1) tool.
% pack200--repack myarchive-packed.jar myarchive.jar
% pack200--repack myarchive.jar
-g --no-gzip
Produces a pack200 file. With this option a suitable compressor
must be used, and the target system must also use a correspond‐
ing decompressor.
% pack200--no-gzip myarchive.pack myarchive.jar
-G --strip-debug
Strips the attributes used for debugging, from the output. These
include SourceFile, LineNumberTable, LocalVariableTable and
LocalVariableTypeTable. Removing these attributes reduces the
size of both downloads and installations but reduces the useful‐
ness of debuggers.
-O --no-keep-file-order
The packer will reorder and transmit all elements. Additionally,
the packer may remove JAR directory names. This will reduce the
download size; however, certain JAR file optimizations such as
indexing, may not work correctly.
-Svalue --segment-limit=value
The value is the estimated target size N (in bytes) of each ar‐
chive segment. If a single input file requires more than N
bytes, it will be given its own archive segment. As a special
case, a value of -1 will produce a single large segment with all
input files, while a value of 0 will produce one segment for
each class. Larger archive segments result in less fragmentation
and better compression, but processing them requires more mem‐
ory.
The size of each segment is estimated by counting the size of
each input file to be transmitted in the segment, along with the
size of its name and other transmitted properties.
The default is 1000000 (a million bytes). This allows input JAR
files of moderate size to be transmitted in one segment. It also
puts a limit on memory requirements for packers and unpackers.
A 10MB JAR packed without this limit will typically pack about
10% smaller, but the packer may require a larger Java heap
(about ten times the segment limit).
-Evalue --effort=value
If the value is set to a single decimal digit, the packer will
use the indicated amount of effort in compressing the archive.
Level 1 may produce somewhat larger size and faster compression
speed, while level 9 will take much longer but may produce bet‐
ter compression. The special value 0 instructs the packer to
copy through the original JAR file directly, with no compres‐
sion. The JSR 200 standard requires any unpacker to understand
this special case as a pass-through of the entire archive.
The default is 5, investing a modest amount of time to produce
reasonable compression.
-Hvalue --deflate-hint=value
Overrides the default, which preserves the input information,
but may cause the transmitted archive to be larger.
The possible values are:
true
false
In either case, the packer will set the deflation hint
accordingly in the output archive, and will not transmit
the individual deflation hints of archive elements.
keep
Preserve deflation hints observed in the input JAR. (This
is the default.)
-mvalue --modification-time=value
The possible values are:
latest
The packer will attempt to determine the latest modifica‐
tion time, among all the available entries in the original
archive, or the latest modification time of all the avail‐
able entries in that segment. This single value will be
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.
keep
Preserve modification times observed in the input JAR.
(This is the default.)
-Pfile -pass-file=file
Indicates that a file should be passed through byte-wise with no
compression. By repeating the option, multiple files may be
specified,. There is no pathname transformation, except that
the system file separator is replaced by the JAR file separator
'/'. The resulting file names must match exactly as strings with
their occurrences in the JAR file. If file is a directory name,
all files under that directory will be passed.
-Uaction --unknown-attribute=action
Overrides the default behavior, ie. the classfile containing the
unknown attribute will be passed through with the specified
action.
The possible values for actions are:
error:
The pack200 operation as a whole will fail, with a suit‐
able explanation.
strip:
The attribute will be dropped. Note: removing the VM
required attributes may cause Class Loader failures.
pass:
Upon encountering this attribute, the entire class will be
transmitted as though it is a resource. (This is the
default.)
-Cattribute-name=layout --class-attribute=attribute-name=action
-Fattribute-name=layout --field-attribute=attribute-name=action
-Mattribute-name=layout --method-attribute=attribute-name=action
-Dattribute-name=layout --code-attribute=attribute-name=action
With the above four options, the attribute layout can be speci‐
fied 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)
The layout language is defined in the JSR 200 specifica‐
tion. For example --class-attribute=SourceFile=RUH.
error
upon encountering this attribute, the pack200 operation
will fail, with a suitable explanation.
strip
upon encountering this attribute, the attribute will be
removed from the output. Note: removing the VM required
attributes may cause Class Loader failures.
pass
upon encountering this attribute, the entire class will be
transmitted as though it is a resource.
Example --class-attribute=CompilationID=pass, will cause
the classfile containing this attribute to be passed
through, without further action by the packer.
-fpack.properties --config-file=pack.properties
A configuration file, containing Java properties to initialize
the packer, may be specified on the command line.
% pack200-f pack.properties myarchive.pack.gz myarchive.jar
% cat 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
Non-Standard Options
-v --verbose Outputs minimal messages, multiple specification of
this option will output more verbose messages.
-q --quiet Quiet operation with no messages.
-lfilename --log-file=filename
A log file to output messages.
-Joption Passes option to the Java launcher called by
pack200. For example, -J-Xms48m sets the startup
memory to 48 megabytes. Although it does not begin
with -X, it is not a `standard option' of
pack200. It is a common convention for -J to pass
options to the underlying VM executing applications
written in Java.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
SEE ALSOunpack200(1), jar(1), jarsigner(1), attributes(5)
For API specification and other related information:
http://java.sun.com/j2se/5.0/docs
http://java.sun.com/j2se/5.0/docs/guide/deployment/deployment-
guide/pack200.html
NOTES:
This command should not be confused with pack(1). They are distinctly
separate products.
The J2SE API Specification provided with the JDK release is the super‐
seding
authority, in case of discrepancies.
14 July 2004 pack200(1)
