Combines multiple files into a single JAR archive file.
SYNOPSIS
jar [ options ] [manifest] destination input-file [input-files]
DESCRIPTION
The jar tool is a java application that combines multiple files
into a single JAR archive file. jar is 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 may be downloaded by
a java agent (like a browser) in a single HTTP transaction, rather
than requiring a new connection for each piece. This dramatically
improves download times. jar also compresses files and so further
improves download time. In addition, it allows individual entries in a
file to be signed by the applet author so that their origin can be
authenticated. The syntax for the jar tool is almost identical to the
syntax for the tar command. A jar archive can be
use as a class path entry, whether it
is compressed or not.
The 3 types of input files for the jar tool are
manifest file (optional)
destination jar file
files to be archived
Typical usage is
% jar cf myjarfile *.class
In this example, all the class files in the current directory are
placed into 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 specification for
details about how meta-information is stored in the manifest file.
If you have a pre-existing manifest file that you want the jar tool to
use for the new jar archive, you can specify it using the -m option:
% jar cmf myManifestFile myJarFile *.class
Note that when you specify "cfm" instead of "cmf" (i.e., 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:
% jar cfm myJarFile myManifestFile *.class
The manifest uses RFC822 ascii format, so it is easy to view and process
manifest-file contents.
Examples of using the Jar tool to operate on Jar files and Jar file
manifests are provided below
and in the Jar trail of the Java Tutorial.
Creates a new or empty archive on the standard output.
t
Lists the table of contents from standard output.
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.
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.
v
Generates verbose output on stderr.
m
Includes manifest information from specified pre-existing manifest file.
Example use:
jar cmf myManifestFile myJarFile *.class
You can add special-purpose name-value attribute headers to the manifest file
that aren't contained in the default manifest. Examples of such headers
would be 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.
0
Store only, without using ZIP compression.
M
Do not create a manifest file for the entries.
u
Update an existing JAR file by adding files or changing the manifest.
For example,
jar uf foo.jar foo.class
would add the file foo.class to the existing JAR file
foo.jar, and
jar umf manifest foo.jar
would update foo.jar's manifest with the information in
manifest.
-C
Temporaily changes directories during execution of jar command
while processing the next argument. Its
operation is intended to be similar to the -C option of
the UNIX tar utility. For example,
jar uf foo.jar -C classes bar.class
would change to the classes directory and add the bar.class
from that directory to foo.jar. The following command,
jar uf foo.jar -C classes . -C bin xyz.class
would change to the classes directory and add to foo.jar all f
iles within the classes directory, but not the
classes directory itself, and then change to the bin directory
and add xyz.class to foo.jar.
If any of "files" is a directory, then that directory is processed recursively.
If you already have subdirectories for images, audio files and classes in
your html directory, I might jar up each directory into a single jar file:
$ ls
audio classes images
$ 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
$ 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
$
You can then see the entry names in the jarfile using the jar tool and the
"t" option:
$ ls
audio bundle.jar classes images
$ 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
$
Enumerating verbosely (with the "v" option) will tell you more information
about the files in the archive, such as their size and last modified date:
$ 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
$