- Create jar file
jar c[v0Mmfe] [manifest
- Update jar file
jar u[v0Mmfe] [manifest
- Extract jar file
jar x[vf] [jarfile
- List table of contents of jar file
jar t[vf] [jarfile
- Add index to jar file
- Options that control the
- Jar file to be created (
c), updated (
u), extracted (
x), or have its table of contents viewed (
t). The -f option and filename jarfile are a pair -- if either is present, they must both appear. Note that omitting
fand jarfile accepts a "jar file" from standard input (for x and t) or sends the "jar file" to standard output (for c and u).
- Files or directories, separated by spaces, to be combined into jarfile (for c and u), or to be extracted (for x) or listed (for t) from jarfile. All directories are processed recursively. The files are compressed unless option 0 (zero) is used.
- Pre-existing manifest file whose name
:value pairs are to be included in MANIFEST.MF in the jar file. The -m option and filename manifest are a pair -- if either is present, they must both appear. The letters m, f and e must appear in the same order that manifest, jarfile, entrypoint appear.
- The name of the class that set as the application entry point for stand-alone applications bundled into executable jar file. The -e option and entrypoint are a pair -- if either is present, they must both appear. The letters m, f and e must appear in the same order that manifest, jarfile, entrypoint appear.
- Temporarily changes directories to dir while processing the following inputfiles argument. Multiple
-Cdir inputfiles sets are allowed.
- Option to be passed into the Java runtime environment. (There must be no space between -J and option).
The jar tool 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 package java applets or applications into a single archive. When the components of an applet or application (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 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 used as a class path entry, whether or not it is compressed.
Typical usage to combine files into a jar file is:In this example, all the class files in the current directory are placed into the file named myFile.jar. The jar tool automatically generates a manifest file entry named% jar cf myFile.jar *.class
META-INF/MANIFEST.MF. It is always the first entry in the jar file. The manifest file declares meta-information about the archive, and stores that data as name : value pairs. Refer to the JAR file specification for details explaining how the jar tool stores meta-information in the manifest file.
If a jar file should include name : value pairs contained in an existing manifest file, specify that file using the -m option:An existing manifest file must end with a new line character. jar does not parse the last line of a manifest file if it does not end with a new line character.% jar cmf myManifestFile myFile.jar *.class
Note: A jar command that specifies cfm on the command line instead of cmf (the order of the m and -f options are reversed), the jar command line must specify the name of the jar archive first, followed by the name of the manifest file:The manifest is in a text format inspired by RFC822 ASCII format, so it is easy to view and process manifest-file contents.% jar cfm myFile.jar myManifestFile *.class
To extract the files from a jar file, use
x:% jar xf myFile.jar
To extract individual files from a jar file, supply their filenames:% jar xf myFile.jar foo bar
Beginning with version 1.3 of the Java 2 SDK, the jar utility supports JarIndex, which allows application class loaders to load classes more efficiently from jar files. If an application or applet is bundled into multiple jar files, only the necessary jar files will be downloaded and opened to load classes. This performance optimization is enabled by running jar with the -ioption. It will generate package location information for the specified main jar file and all the jar files it depends on, which need to be specified in the Class-Path attribute of the main jar file's manifest.% jar i main.jar
In this example, an
INDEX.LISTfile is inserted into the
The application class loader uses the information stored in this file for efficient class loading. For details about how location information is stored in the index file, refer to the JarIndex specification.
To copy directories, first compress files in
stdout, then extract from
dir2(omitting the -f option from both
jarcommands):% (cd dir1; jar c .) | (cd dir2; jar x)
To review command samples which use
jarto opeate on jar files and jar file manifests, see Examples, below. Also refer to the jar trail of the Java Tutorial.
- Creates a new archive file named jarfile (if
fis specified) or to standard output (if
fand jarfile are omitted). Add to it the files and directories specified by inputfiles.
- Updates an existing file jarfile (when
fis specified) by adding to it files and directories specified by inputfiles. For example:would add the file foo.class to the existing jar file foo.jar. The -u option can also update the manifest entry, as given by this example:jar uf foo.jar foo.classupdates the foo.jar manifest with the name : value pairs in manifest.jar umf manifest foo.jar
- Extracts files and directories from jarfile (if
fis specified) or standard input (if
fand jarfile are omitted). If inputfiles is specified, only those specified files and directories are extracted. Otherwise, all files and directories are extracted. The time and date of the extracted files are those given in the archive.
- Lists the table of contents from jarfile (if
fis specified) or standard input (if
fand jarfile are omitted). If inputfiles is specified, only those specified files and directories are listed. Otherwise, all files and directories are listed.
- Generate index information for the specified jarfile and its dependent jar files. For 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 the Class-Path attribute of foo.jar. See the index example.
- Specifies the file jarfile to be created (
c), updated (
u), extracted (
x), indexed (
i), or viewed (
t). The -f option and filename jarfile are a pair -- if present, they must both appear. Omitting
fand jarfile accepts a jar file name from
stdin(for x and t) or sends jar file to
stdout(for c and u).
- Generates verbose output to standard output. Examples shown below.
- (zero) Store without using ZIP compression.
- Do not create a manifest file entry (for c and u), or delete a manifest file entry if one exists (for u).
- Includes name : value attribute pairs from the specified manifest file manifest in the file at META-INF/MANIFEST.MF.
jaradds a name : value pair unless an entry already exists with the same name, in which case
jarupdates its value.
On the command line, the letters m and f must appear in the same order that manifest and jarfile appear. Example use:You can add special-purpose name : value attribute pairs to the manifest that aren't contained in the default manifest. For example, you can add attributes specifying vendor information, version information, package sealing, or to make JAR-bundled applications executable. See the JAR Files trail in the Java Tutorial for examples of using the -m option.jar cmf myManifestFile myFile.jar *.class
- Sets entrypoint as the application entry point for stand-alone applications bundled into executable jar file. The use of this option creates or overrides the Main-Class attribute value in the manifest file. This option can be used during creation of jar file or while updating the jar file. This option specifies the application entry point without editing or creating the manifest file.
For example, this command creates
Main.jarwhere the Main-Class attribute value in the manifest is set to
Main:jar cfe Main.jar Main Main.class
The java runtime can directly invoke this application by running the following command:If the entrypoint class name is in a package it may use either a dot (".") or slash ("/") character as the delimiter. For example, ifjava -jar Main.jar
Main.classis in a package called
foothe entry point can be specified in the following ways:orjar -cfe Main.jar foo/Main foo/Main.classNote: specifying bothjar -cfe Main.jar foo.Main foo/Main.class
-mand -e options together when the given manifest also contains the Main-Class attribute results in an ambigous
Main.classspecification, leading to an error and the jar creation or update operation is aborted.
- -C dir
- Temporarily changes directories (
cddir) during execution of the jar command while processing the following inputfiles argument. Its operation is intended to be similar to the -C option of the UNIX tar utility.
For example, this command changes to the classes directory and adds the bar.class from that directory to foo.jar:This command changes to the classes directory and adds to foo.jar all files within the classes directory (without creating a classes directory in the jar file), then changes back to the original directory before changing to the bin directory to add xyz.class to foo.jar.jar uf foo.jar -C classes bar.classIfjar uf foo.jar -C classes . -C bin xyz.class
bar2, then here's what the jar file will contain using
jar tf foo.jar:META-INF/ META-INF/MANIFEST.MF bar1 bar2 xyz.class
- Pass option to the Java runtime environment, where option is one of the options described on the reference page for the java application launcher. For example,
-J-Xmx48Msets the maximum memory to 48 megabytes. It is a common convention for -J to pass options to the underlying runtime environment.
To shorten or simplify the jar command line, you can specify one or more files that themselves contain arguments to the
-Joptions). This enables you to create jar commands of any length, overcoming command line limits imposed by the operating system.
An argument file can include options and filenames. The arguments within a file can be spaceseparated or newline-separated. Filenames within an argument file are relative to the current directory, not relative to the location of the argument file. Wildcards (*) that might otherwise be expanded by the operating system shell are not expanded. Use of the @ character to recursively interpret files is not supported. The -J options are not supported because they are passed to the launcher, which does not support argument files.
jar, pass in the path and name of each argument file with the @ leading character. When
jarencounters an argument beginning with the character @, it expands the contents of that file into the argument list.
The example below,
classes.listholds the names of files output by a
findcommand:% find . -name '*.class' -print > classes.list
You can then execute the
Classes.listby passing it to
jarusing argfile syntax:An argument file can specify a path, but any filenames inside the argument file that have relative paths are relative to the current working directory, not to the path passed in. Here is an example:% jar cf my.jar @classes.list% jar @path1/classes.list
To add all the files in a particular directory to an archive (overwriting contents if the archive already exists). 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.If you already have separate subdirectories for images, audio files and classes, you can combine them into a single jar file:% ls 1.au Animator.class monkey.jpg 2.au Wave.class spacemusic.au 3.au at_work.gif % jar cvf bundle.jar * added manifest adding: 1.au(in = 2324) (out= 67)(deflated 97%) adding: 2.au(in = 6970) (out= 90)(deflated 98%) adding: 3.au(in = 11616) (out= 108)(deflated 99%) adding: Animator.class(in = 2266) (out= 66)(deflated 97%) adding: Wave.class(in = 3778) (out= 81)(deflated 97%) adding: at_work.gif(in = 6621) (out= 89)(deflated 98%) adding: monkey.jpg(in = 7667) (out= 91)(deflated 98%) adding: spacemusic.au(in = 3079) (out= 73)(deflated 97%)To see the entry names in the jarfile, use the t option:% ls -F audio/ classes/ images/ % jar cvf bundle.jar audio classes images added manifest adding: audio/(in = 0) (out= 0)(stored 0%) adding: audio/1.au(in = 2324) (out= 67)(deflated 97%) adding: audio/2.au(in = 6970) (out= 90)(deflated 98%) adding: audio/3.au(in = 11616) (out= 108)(deflated 99%) adding: audio/spacemusic.au(in = 3079) (out= 73)(deflated 97%) adding: classes/(in = 0) (out= 0)(stored 0%) adding: classes/Animator.class(in = 2266) (out= 66)(deflated 97%) adding: classes/Wave.class(in = 3778) (out= 81)(deflated 97%) adding: images/(in = 0) (out= 0)(stored 0%) adding: images/monkey.jpg(in = 7667) (out= 91)(deflated 98%) adding: images/at_work.gif(in = 6621) (out= 89)(deflated 98%) % ls -F audio/ bundle.jar classes/ images/% jar tf bundle.jar META-INF/ 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
To add an index file to the jar file for speeding up class loading, use the i option.
If you split the inter-dependent classes for a stock trade application into three jar files: main.jar, buy.jar, and sell.jar.
If you specify the Class-path attribute in the main.jar manifest as:Class-Path: buy.jar sell.jarthen you can use the -i option to speed up the class loading time for your application:% jar i main.jarAn
INDEX.LISTfile is inserted to the
META-INFdirectory. This enables the application class loader to download the specified jar files when it is searching for classes or resources.
The Jar Overview
The Jar File Specification
The JarIndex Spec
Jar Tutorial on the Java Software web site.
pack200 Reference Page