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java(1)								       java(1)

NAME
       java - Java application launcher

SYNOPSIS
       java [ options ] class [ argument...  ]

       java [ options ] -jar file.jar
	    [ argument...  ]

PARAMETERS
       options	      Command-line options.

       class	      Name of the class to be invoked.

       file.jar	      Name  of the jar file to be invoked.  Used only with the
		      -jar option.

       argument	      Argument passed to the main function.

DESCRIPTION
       The java tool launches a Java application.  It does this by starting  a
       Java  runtime environment, loading a specified class, and invoking that
       class's main method.  The method must be declared public and  static  ,
       it  must	 not  return any value, and it must accept a String array as a
       parameter. The method declaration must look like the following:

	  public static void main(String args[])

       By default, the first non-option argument is the name of the  class  to
       be  invoked.  A fully-qualified class name should be used.  If the -jar
       option is specified, the first non-option argument is the name of a JAR
       archive	containing  class and resource files for the application, with
       the startup class indicated by the Main-Class manifest header.

       The Java runtime searches for the  startup  class,  and	other  classes
       used,  in  three	 sets  of  locations:  the  bootstrap  class path, the
       installed extensions, and the user class path.

       Non-option arguments after the class name or JAR file name  are	passed
       to the main function.

OPTIONS
       The  launcher  has  a set of standard options that are supported on the
       current runtime environment and will be supported in  future  releases.
       In  addition, the current impletmentations of the virtual machines sup‐
       port a set of non-standard options that are subject to change in future
       releases.

   Standard Options
       -client		   Selects  the	 Java  HotSpot	Client	VM.   For more
			   information see Server-Class Machine	 Detection  at
			   http://java.sun.com/j2se/1.5.0/docs/guide/vm/server-
			   class.html

       -server		   Selects the	Java  HotSpot  Server  VM.   For  more
			   information	see  Server-Class Machine Detection at
			   http://java.sun.com/j2se/1.5.0/docs/guide/vm/server-
			   class.html

       -agentlib:libname[=options]
			   Load native agent library libname, e.g.,

	    -agentlib:hprof
	    -agentlib:jdwp=help
	    -agentlib:hprof=help

       For   more  information,	 see  JVMTI  Agent  Command  Line  Options  at
       http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html

       -agentpath:pathname[=options]
	      Load a native agent library by full pathname. For more  informa‐
	      tion,    see    JVMTI    Agent	Command	   Line	  Options   at
	      http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html

       -classpath classpath
       -cp classpath
	      Specifies a list of directories, JAR archives, and ZIP  archives
	      to  search for class files.  Class path entries are separated by
	      colons (:). Specifying -classpath or -cp overrides  any  setting
	      of the CLASSPATH environment variable.

	      If -classpath and -cp are not used and CLASSPATH is not set, the
	      user class path consists of the current directory (.).

       -Dproperty=value
	      Sets a system property value.

       -d32, -d64
	      Specified whether the program is to be run in a 32-bit or 64-bit
	      environment if available.

	      Currently, only the Java HotSpot Server VM supports 64-bit oper‐
	      ations and the -server option is implicit with the use of -d64 .
	      This is subject to change in a future release.

	      If  neither -d32 nor -d64 is specified, the default is to run in
	      a 32-bit environment, except for 64-bit only systems.   This  is
	      subject to change in a future release.

       -enableassertions :<package name>... |:<class name>
       -ea :<package name>... |:<class name>
	      Enable assertions. Assertions are disabled by default.

	      With  no	arguments,  enableassertions or -ea enable assertions.
	      With one argument ending in "...", the switch enables assertions
	      in the specified package and any subpackages. If the argument is
	      simply "...", the switch enables assertions in the unnamed pack‐
	      age in the current working directory. With one argument not end‐
	      ing in "...", the switch enables	assertions  in	the  specified
	      class.

	      If  a  single  command line contains multiple instances of these
	      switches,	 they  are  processed  in  order  before  loading  any
	      classes.	So,  for  example,  to	run  a program with assertions
	      enabled only in package com.wombat.fruitbat  (and	 any  subpack‐
	      ages), the following command could be used:

	      java -ea:com.wombat.fruitbat... <Main Class>

	      The  -enableassertions  and  -ea switches apply to all s loaders
	      and to system classes (which do not have a class loader).	 There
	      is  one  exception  to this rule: in their no-argument form, the
	      switches do not apply to system.	This makes it easy to turn  on
	      asserts  in  all	classes	 except for system classes. A separate
	      switch is provided to enable asserts in all system classes;  see
	      -enablesystemassertions below.

       -disableassertions :<package name>... |:<class name>
       -da :<package name>... |:<class name>/fR
	      Disable assertions. This is the default.

	      With no arguments, disableassertions or -da disables assertions.
	      With one argument ending in "...", the  switch  disables	asser‐
	      tions in the specified package and any subpackages. If the argu‐
	      ment is simply "...", the	 switch	 disables  assertions  in  the
	      unnamed package in the rent working directory. With one argument
	      not ending in "...", the switch disables assertions in the spec‐
	      ified class.

	      To  run  a  program  with assertions enabled in package com.wom‐
	      bat.fruitbat but disabled in class com.wombat.fruitbat.Brickbat,
	      the following command could be used:

	      java -ea:com.wombat.fruitbat... -da:com.wombat.fruitbat.Brickbat
	      <Main Class>

	      The -disableassertions and -da switches apply to all ss  loaders
	      and to system classes (which do not have a class loader).	 There
	      is one exception to this rule: in their  no-argument  form,  the
	      switches	do  not apply to system. This makes it easy to turn on
	      asserts in all classes except for	 system	 classes.  A  separate
	      switch  is provided to enable asserts in all system classes; see
	      -disablesystemassertions below.

       -enablesystemassertions
       -esa   Enable asserts in all system classes (sets the default assertion
	      status for system classes to true).

       -disablesystemassertions
       -dsa   Disables asserts in all system classes

       -jar   Execute  a  program  encapsulated	 in  a JAR archive.  The first
	      argument is the name of a JAR file instead of  a	startup	 class
	      name.  In order for this option to work, the manifest of the JAR
	      file must contain	 a  line  of  the  form	 Main-Class:classname.
	      Here,  classname	identifies  the class having the public static
	      void main(String[] args) method that  serves  as	your  applica‐
	      tion's  starting point.  See the Jar tool reference page and the
	      Jar trail of the Java Tutorial  for  information	about  working
	      with Jar files and Jar-file manifests.

	      When you use this option, the JAR file is the source of all user
	      classes, and other user class path settings are ignored.

	      Note that JAR files that can be run with the "java -jar"	option
	      can  have their execute permissions set so they can be run with‐
	      out using "java -jar". Refer to Java Archive (JAR) Files.

       -javaagent:jarpath[=options]
	      Load a Java programming language	agent,	see  java.lang.instru‐
	      ment.

       -verbose
       -verbose:class
	      Displays information about each class loaded.

       -verbose:gc
	      Reports on each garbage collection event.

       -verbose:jni
	      Reports  information  about use of native methods and other Java
	      Native Interface activity.

       -version
	      Displays version information and exit.

       -showversion
	      Displays version information and continues.

       -?
       -help  Displays usage information and exit.

       -X     Displays information about non-standard options and exit.

   Non-Standard Options
       -Xint		   Operates in interpreted-only mode.  Compilation  to
			   native code is disabled, and all bytecodes are exe‐
			   cuted by the interpreter.  The performance benefits
			   offered  by the Java HotSpot VMs' adaptive compiler
			   will not be present in this mode.

       -Xbatch		   Disable background  compilation.  Normally  the  VM
			   will	 compile the method as a background task, run‐
			   ning the method in interpreter mode until the back‐
			   ground  compilation	is  finished. The -Xbatch flag
			   disables background compilation so that compilation
			   of  all methods proceeds as a foreground task until
			   completed.

       -Xdebug		   Start with support for  JVMDI  enabled.  JVMDI  has
			   been	 deprecated  and  is not used for debugging in
			   J2SE 5.0, so this option isn't needed for debugging
			   in J2SE 5.0.

       -Xbootclasspath:bootclasspath
			   Specify  a colon-separated list of directories, JAR
			   archives, and ZIP archives to search for boot class
			   files.   These  are used in place of the boot class
			   files included in the Java 2	 SDK.  Note:  Applica‐
			   tions that use this option for the purpose of over‐
			   riding a class in rt.jar should not be deployed  as
			   doing  so would contravene the Java 2 Runtime Envi‐
			   ronment binary code license.

       -Xbootclasspath/a:path
			   Specifies a colon-separated	path  of  directories,
			   JAR	archives,  and	ZIP  archives to append to the
			   default bootstrap class path.

       -Xbootclasspath/p:path
			   Specifies a colon-separated	path  of  directories,
			   JAR	archives, and ZIP archives to prepend in front
			   of the default bootstrap class path.	 Note:	Appli‐
			   cations  that  use  this  option for the purpose of
			   overriding  a  class	 in  rt.jar  should   not   be
			   deployed,  as  doing so would contravene the Java 2
			   Runtime Environment binary code license.

       -Xcheck:jni	   Perform additional checks for Java Native Interface
			   (JNI)  functions.   Specifically,  the Java Virtual
			   Machine validates the parameters passed to the  JNI
			   function  as	 well  as the runtime environment data
			   before processing the JNI request. Any invalid data
			   encountered indicates a problem in the native code,
			   and the Java Virtual Machine will terminate with  a
			   fatal  error	 in  such  cases. Expect a performance
			   degradation when this option is used.

       -Xfuture		   Performs strict class-file format checks.  For pur‐
			   poses  of backwards compatibility, the default for‐
			   mat checks performed by the Java  2	SDK's  virtual
			   machine  are	 no stricter than the checks performed
			   by 1.1.x versions of the JDK software.   The	 -Xfu‐
			   ture	 flag  turns  on  stricter  class-file	format
			   checks  that	 enforce  closer  conformance  to  the
			   class-file  format  specification.	Developers are
			   encouraged to use this  flag	 when  developing  new
			   code	 because  the  stricter checks will become the
			   default in future releases of the Java  application
			   launcher.

       -Xnoclassgc	   Disables class garbage collection

       -Xincgc		   Enable   the	 incremental  garbage  collector.  The
			   incremental garbage	collector,  which  is  off  by
			   default, will reduce the occasional garbage-collec‐
			   tion pauses during program execution. The incremen‐
			   tal garbage collector will at times execute concur‐
			   rently with the program and during such times  will
			   reduce the processor capacity available to the pro‐
			   gram.

       -Xloggc: file	   Report on each garbage collection  event,  as  with
			   -verbose:gc,	 but  log this data to file.  In addi‐
			   tion to the	information  -verbose:gc  gives,  each
			   reported  event  will  be preceeded by the time (in
			   seconds) since the first garbage-collection event.

			   Always use a local file system for storage of  this
			   file	 to  avoid  stalling  the  JVM	due to network
			   latency.  The file may be truncated in the case  of
			   a full file system and logging will continue on the
			   truncated file.  This option overrides  -verbose:gc
			   if both are given on the command line.

       -Xmsn		   Specifies the initial size of the memory allocation
			   pool.  This	value  must  be	 a  multiple  of  1024
			   greater  than  1  MB.   Append the letter k or K to
			   indicate kilobytes, the letter m or M  to  indicate
			   megabytes, the letter g or G to indicate gigabytes,
			   or the letter t or T to  indicate  terabytes.   The
			   default value is 2MB. Examples:

			   -Xms6291456
			   -Xms6144k
			   -Xms6m

       -Xmxn		   Specifies the maximum size, in bytes, of the memory
			   allocation pool.  This value must be a multiple  of
			   1024	 greater  than 2 MB.  Append the letter k or K
			   to indicate kilobytes, the letter m or M  to	 indi‐
			   cate megabytes, the letter g or G to indicate giga‐
			   bytes, or the letter t or T to indicate  terabytes.
			   The default value is 64MB. Examples:

			   -Xmx83886080
			   -Xmx81920k
			   -Xmx80m

			   On  Mac  OS	X  platforms, the upper limit for this
			   value when running in 32-bit mode (-d32) is approx‐
			   imately  2100m minus overhead amounts, and approxi‐
			   mately 127t minus overhead amounts when running  in
			   64-bit  mode	 (-d64).   On  Solaris 7 and Solaris 8
			   SPARC platforms, the upper limit for this value  is
			   approximately  4000m	 minus	overhead  amounts.  On
			   Solaris 2.6 and x86 platforms, the upper  limit  is
			   approximately  2000m	 minus	overhead  amounts.  On
			   Linux platforms, the upper limit  is	 approximately
			   2000m minus overhead amounts.

       -Xprof		   Profiles  the  running program, and sends profiling
			   data to standard output.  This option  is  provided
			   as  a utility that is useful in program development
			   and is not intended to be  be  used	in  production
			   systems.

       -Xrunhprof[:help][:suboption=value,...]
			   Enables  cpu,  heap,	 or  monitor  profiling.  This
			   option is typically followed by a  list  of	comma-
			   separated  suboption=value  pairs.  Run the command
			   java -Xrunhprof:help to obtain a list of suboptions
			   and their default values.

       -Xrs		   Reduce  usage  of  operating-system signals by Java
			   virtual machine (JVM).

			   In a previous release, the Shutdown Hooks  facility
			   was	added  to  allow  orderly  shutdown  of a Java
			   application. The intent was to allow	 user  cleanup
			   code	 (such as closing database connections) to run
			   at shutdown, even if the JVM terminates abruptly.

			   Sun's JVM catches  signals  to  implement  shutdown
			   hooks  for  abnormal	 JVM termination. The JVM uses
			   SIGHUP, SIGINT, and SIGTERM to initiate the running
			   of shutdown hooks.

			   The	JVM  uses a similar mechanism to implement the
			   pre-1.2 feature of dumping thread stacks for debug‐
			   ging	 purposes.  Sun's  JVM uses SIGQUIT to perform
			   thread dumps.

			   Applications that embed the JVM frequently need  to
			   trap signals like SIGINT or SIGTERM, which can lead
			   to interference with the JVM's own signal handlers.
			   The	-Xrs  command  line  option  is	 available  to
			   address this issue.	When -Xrs  is  used  on	 Sun's
			   JVM,	 the signal masks for SIGINT, SIGTERM, SIGHUP,
			   and SIGQUIT are not changed by the JVM, and	signal
			   handlers for these signals are not installed.

			   There are two consequences of specifying -Xrs:

			   · SIGQUIT thread dumps are not available.

			   · User  code	 is  responsible  for causing shutdown
			     hooks  to	run,  for  example  by	calling	  Sys‐
			     tem.exit() when the JVM is to be terminated.

       -Xssn		   Set thread stack size.

       -XX:+UseAltSigs	   The	VM  uses SIGUSR1 and SIGUSR2 by default, which
			   can sometimes conflict with applications that  sig‐
			   nal-chain SIGUSR1 and SIGUSR2.  The -XX:+UseAltSigs
			   option will cause the VM to use signals other  than
			   SIGUSR1 and SIGUSR2 as the default.

SEE ALSO
       javac(1), jdb(1), javah(1), jar(1),

       See (or search java.sun.com) for the following:

       The Java Extensions Framework @
	 http://java.sun.com/j2se/1.5.0/docs/guide/extensions/index.html

       Security Features @
	 http://java.sun.com/j2se/1.5.0/docs/guide/security/index.html

				 23 June 2004			       java(1)
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