jar(1) jar(1)
NAME
jar - Java archive tool
SYNOPSIS
jar [ -C ] [ c ] [ f ] [ i ] [ M ] [ m ] [ O ] [ t ] [ u ] [ v ] [ J
option ]
[ x file ] [ manifest-file ] destination input-file
[ input-files ]
DESCRIPTION
The jar tool is a Java(tm) application that combines multiple files
into a single JAR archive file. It is also a general-purpose archiving
and compression tool, based on ZIP and the ZLIB compression format.
However, jar was designed mainly to facilitate the packaging of Java
applets or applications into a single archive. When the components of
an applet or application (.class files, images and sounds) are combined
into a single archive, they can be downloaded by a Java agent (like a
browser) in a single HTP transaction, rather than require a new con-
nection for each piece. This dramatically improves download time. The
jar tool also compresses files, which further improves download time.
In addition, it allows individual entries in a file to be signed by the
applet author so that their origins can be authenticated. The syntax
for the jar tool is almost identical to the syntax for the tar(1) com-
mand. A JAR archive can be used as a class path entry, whether or not
it is compressed.
The three types of input files for the jar tool are:
]o Manifest file (optional)
]o Destination JAR file
]o Files to be archived
Typical usage is:
example%% jar cf myjarfile **.class
In this example, all the class files in the current directory are
placed in the file named myjarfile. A manifest file is automatically
generated by the jar tool and is always the first entry in the JAR
file. By default, it is named META-INF/MANIFEST.MF. The manifest file
is the place where any meta-information about the archive is stored.
Refer to the Manifest Format in the SEE ALSO section for details about
how meta-information is stored in the manifest file.
To use a pre-existing manifest file to create a new JAR archive, spec-
ify the old manifest file with the m option:
example%% jar cmf myanifestFile myJarFile **.class
When you specify cfm instead of cmf (that is, you invert the order of
the m and f options), you need to specify the name of the JAR archive
first, followed by the name of the manifest file:
example%% jar cfm myJarFile myanifestFile **.class
The manifest uses RFC822 ASCI format, so it is easy to view and
process manifest-file contents.
OPTIONS
The following options are supported:
-C Changes directories during execution of the jar command. For
example:
example%% jar uf foo.jar -C classes **
c Creates a new or empty archive on the standard output.
f The second argument specifies a JAR file to process. In the case
of creation, this refers to the name of the JAR file to be created
(instead of on stdout). For table or xtract, the second argument
identifies the JAR file to be listed or extracted.
i Generates index information for the specified JAR file and its
dependent JAR files. For example,
example%% jar i foo.jar
would generate an INDEX.LIST file in foo.jar which contains location
information for each package in foo.jar and all the JAR files specified
in foo.jar's Class-Path attribute.
-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. It is a common convention for -J to pass options
to the underlying virtual machine.
M Does not create a manifest file for the entries.
m Includes manifest information from specified pre-existing manifest
file. Example use:
example%% jar cmf myanifestFile myJarFile **.class
You can add special-purpose name-value attribute headers to the
manifest file that are not contained in the default manifest.
Examples of such headers are those for vendor information, version
information, package sealing, and headers to make JAR-bundled
applications executable. See the JAR Files trail in the Java
Tutorial and the JRE Notes for Developers web page for examples of
using the m option.
O Stores only, without using ZIP compression.
t Lists the table of contents from standard output.
u Updates an existing JAR file by adding files or changing the mani-
fest. For example:
example%% jar uf foo.jar foo.class
adds the file foo.class to the existing JAR file foo.jar, and
example%% jar umf foo.jar
updates foo.jar's manifest with the information in manifest.
v Generates verbose output on stderr.
x file
Extracts all files, or just the named files, from standard input.
If file is omitted, then all files are extracted; otherwise, only
the specified file or files are extracted.
If any of the files is a directory, then that directory is pro-
cessed recursively.
EXAMPLES
Adding all of the files in a particular directory to an archive
To add all of the files in a particular directory to an archive:
example%% ls
00.au 3.au 6.au 9.au atwork.gif
1.au 4.au 7.au Animator.class monkey.jpg
e.au 5.au 8.au Wave.class spacemusic.au
example%% jar cvf bundle.jar **
adding:: 00.au
adding:: 1.au
adding:: 2.au
adding:: 3.au
adding:: 4.au
adding:: 5.au
adding:: 6.au
adding:: 7.au
adding:: 8.au
adding:: 9.au
adding:: Animator.class
adding:: Wave.class
adding:: atwork.gif
adding:: monkey.jpg
adding:: spacemusic.au
example%%
Archiving subdirectories
If you already have subdirectories for images, audio files, and classes
that already exist in an HTML directory, use jar to archive each direc-
tory to a single JAR file:
example%% ls
audio classes images
example%% jar cvf bundle.jar audio classes images
adding:: audio/1.au
adding:: audio/2.au
adding:: audio/3.au
adding:: audio/spacemusic.au
adding:: classes/Animator.class
adding:: classes/Wave.class
adding:: images/monkey.jpg
adding:: images/atwork.gif
example%% ls -l
total 142
drwxr-xr-x 2 brown green 512 Aug 1 22::33 audio
-rw-r--r-- 1 brown green 68677 Aug 1 22::36 bundle.jar
drwxr-xr-x 2 brown green 512 Aug 1 22::26 classes
drwxr-xr-x 2 brown green 512 Aug 1 22::25 images
example%%
Finding entry names in the JAR file
To see the entry names in the JAR file using the jar tool and the t
option:
example%% ls
audio bundle.jar classes images
example%% jar tf bundle.jar
META-INF/MANIFEST.MF
audio/1.au
audio/2.au
audio/3.au
audio/spacemusic.au
classes/Animator.class
classes/Wave.class
images/monkey.jpg
images/atwork.gif
example%%
Displaying more information about files in the archive
To display more information about the files in the archive, such as
their size and last modified date, use the v option:
example%% jar tvf bundle.jar
145 Thu Aug 001 22::27::0000 PDT 1996 META-INF/MANIFEST.MF
946 Thu Aug 001 22::24::22 PDT 1996 audio/1.au
10039 Thu Aug 001 22::24::22 PDT 1996 audio/2.au
993 Thu Aug 001 22::24::22 PDT 1996 audio/3.au
480072 Thu Aug 001 22::24::23 PDT 1996 audio/spacemusic.au
16711 Thu Aug 001 22::25::500 PDT 1996 classes/Animator.class
3368 Thu Aug 001 22::26::002 PDT 1996 classes/Wave.class
128009 Thu Aug 001 22::24::48 PDT 1996 images/monkey.jpg
527 Thu Aug 001 22::25::200 PDT 1996 images/atwork.gif
example%%
Speeding up an application''s class loading time
If you bundled a stock trade application (applet) into the following
JAR files,
main.jar buy.jar sell.jar other.jar
and you specified the Class-Path attribute in main.jar's manifest as
Class-Path:: buy.jar sell.jar other.jar
then you can use the i option to speed up your application's class
loading time:
example$$ jar i main.jar
An INDEX.LIST file is inserted in the META-INF directory which will
enable the application class loader to download the right JAR files
when it is searching for classes or resources.
SEE ALSO
keytool(1)
JAR Files @
http:/java.sun.com/docs/books/tutorial/jar/
JRE Notes @
http:/java.sun.com/j2se/1.4/runtime.html#example
JAR Guide @
http:/java.sun.com/j2se/1.4/docs/guide/jar/index.html
For information on related topics, use the search link @
http:/java.sun.com/
14 July 2000 jar(1)
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