# jar-The Java Archive Tool

> 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.

> 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.INF. 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

> When files are added to a jar archive, the file and its MD5 and SHA hashes are stored. The hashes are entered into the manifest file. It is easy to view and process the contents of the manifest file, since it uses RFC822 ascii format.

## OPTIONS

> `c`
>   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 `c`reation, this refers to the name of the jar file to be created (instead of on stdout). For `t`able or `x`tract, 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, and package sealing. See the JAR Files trail in the Java Tutorial for examples of using the `m` option.

> `0`
>   Store only, without using ZIP compression.

> `M`
>   Do not create a manifest file for the entries.

If any of `"files"` is a directory, then that directory is processed recursively.

## EXAMPLES

> To add all the files in a particular directory to an archive:

>     $ ls
>     0.au            3.au            6.au            9.au            at_work.gif
>     1.au            4.au            7.au            Animator.class  monkey.jpg
>     2.au            5.au            8.au            Wave.class      spacemusic.au
>     $ 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
>     $

> If already have subdirectories for images, audio files and classes in my 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
>     $

> I 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 me 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
>     $

> ## SEE ALSO

> > jar guide
> > javakey
> > manifest file format