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 mul-
tiple 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 HTTP transaction, rather than require a new con-
nection for each piece. This dramatically improves down-
load time. The jar tool also compresses files, which fur-
ther improves download time. In addition, it allows indi-
vidual 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) command. 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 direc-
tory 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 sec-
tion 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, specify the old manifest file with the m option:
example% jar cmf myManifestFile 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 myManifestFile *.class
The manifest uses RFC822 ASCII 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 com-
mand. For example:
example% jar uf foo.jar -C classes *
c Creates a new or empty archive on the standard out-
put.
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 con-
tains 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 myManifestFile 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 informa-
tion, package sealing, and headers to make JAR-bun-
dled 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 manifest. 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 direc-
tory is processed recursively.
EXAMPLES
To add all of the files in a particular directory to an
archive:
example% ls
0.au 3.au 6.au 9.au at_work.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: 0.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: at_work.gif
adding: monkey.jpg
adding: spacemusic.au
example%
If you already have subdirectories for images, audio
files, and classes that already exist in an HTML direc-
tory, use jar to archive each directory 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/at_work.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%
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/at_work.gif
example%
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 01 22:27:00 PDT 1996 META-INF/MANIFEST.MF
946 Thu Aug 01 22:24:22 PDT 1996 audio/1.au
1039 Thu Aug 01 22:24:22 PDT 1996 audio/2.au
993 Thu Aug 01 22:24:22 PDT 1996 audio/3.au
48072 Thu Aug 01 22:24:23 PDT 1996 audio/spacemusic.au
16711 Thu Aug 01 22:25:50 PDT 1996 classes/Animator.class
3368 Thu Aug 01 22:26:02 PDT 1996 classes/Wave.class
12809 Thu Aug 01 22:24:48 PDT 1996 images/monkey.jpg
527 Thu Aug 01 22:25:20 PDT 1996 images/at_work.gif
example%
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 applica-
tion'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/1.3/runtime.html#exam-
ple
JAR Guide @
http://java.sun.com/j2se/1.3/docs/guide/jar/index.html
For information on related topics, use the search link @
http://java.sun.com/
14 July 2000 jar(1)