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Java in a Nutshell

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JDK Tools



jar---Java Archive Tool


JDK 1.1 and later.


jar c|t|x[f][m][v] [jar-file] [manifest-file] [files]


jar is a tool that can be used to create and manipulate Java Archive (JAR) files. A JAR file is a compressed ZIP file with an additional "manifest" file. The syntax of the jar command is reminiscent of the Unix tar (tape archive) command.

Options to jar are specified as a block of concatenated letters passed as a single argument, rather than as individual command-line arguments. The first letter of this option argument specifies what action jar is to perform and is required. Other option letters are optional. The various file arguments depend on which option letters are specified.


The first argument to jar is a set of letters that specifies the operation it is to perform. The first letter specifies the basic action and is required. The three possible values are the following:


Create a new JAR archive. A list of input files and/or directories must be specified as the final arguments to jar.


List the contents of a JAR archive. If a JAR file is specified with the f option, its contents are listed. Otherwise, the JAR file to be listed is read from standard input.


Extract the contents of a JAR archive. If a JAR file is specified with the f option, its contents are extracted. Otherwise, the JAR file to be extracted is read from standard input. If the command is followed by a list of files and/or directories, only those files or directories are extracted from the JAR archive. Otherwise, all files in the archive are extracted.

This action specifier can be followed by optional command letters:


This option indicates that the JAR file to create, list, or extract from is specified on the command line. When f is used with c, t, or x, the JAR filename must be the second command-line argument to jar (i.e., it must follow the block of option letters). If this option is not specified, jar writes the JAR file it creates to standard output, or reads a JAR file from standard input.


This option is only used with the c action. It indicates that jar should read the manifest file (partial or complete) specified on the command line and use that file as the basis for the manifest it includes in the JAR file. When this argument is specified after the f option, the manifest filename should follow the destination filename. If m precedes the f option, the manifest filename should precede the destination filename.


Verbose. If this letter is specified with a c action, jar lists each file it adds to the archive with compression statistics. If it is used with a t action, jar lists the size and modification date for each file in the archive, instead of simply listing the filename. If v is used with x, jar displays the name of each file it extracts from the archive.


To create a simple JAR file:

% jar cvf my.jar *.java images

To list the contents of a file:

% jar tvf your.jar

To extract the manifest file from a JAR file:

% jar xf the.jar META-INF/MANIFEST.MF

To create a JAR file with a partial manifest specified:

% jar cfmv YesNoDialog.jar manifest.stub oreilly/beans/yesno

See Also


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