This README file provides information about the Runtime Environment for Linux package provided with IBM Developer Kit for Linux, Java 2 Technology Edition, Version 1.3.0. The Runtime Environment for Linux has been tested with the following products:
The Runtime Environment for Linux has been tested with the following desktops and window managers:
The Runtime Environment for Linux contains the subset of classes required to create a Java runtime environment and to run Java programs. It also contains the Java Virtual Machine, Java classes, and supporting files. The Runtime Environment for Linux contains only a subset of the classes found in the Java Developer Kit.
The Runtime Environment for Linux includes non-debuggable .so files plus class files needed to support a program at runtime. The Runtime Environment for Linux does not include any of the development tools, such as appletviewer or javac, or classes that would pertain only to a development system.
In addition, the Java Authentication and Authorization Service (JAAS) and Java Communications application programming interface (API) packages are provided for use with the Runtime Environment for Linux.
The LICENSE_xx.html file contains the license agreement for the Runtime Environment for Linux software. (xx is an abbreviation for the language.)
To view or print the license agreement, open the file in a Web browser.
The just-in-time (JIT) compiler (libjitc.so) dynamically generates machine code for frequently used bytecode sequences in a Java application or applet while it is running.
The Runtime Environment for Linux includes the JIT compiler (libjitc.so), which is enabled by default. You can disable the JIT to help isolate a problem with a Java application, an applet, or the compiler itself. To disable the JIT, type the following at a shell prompt:
export JAVA_COMPILER=NONE
To enable the JIT, type the following at a shell prompt:
export JAVA_COMPILER=libjitc.so
To verify whether or not the JIT is enabled, type the following at a shell prompt:
java -version
If the JIT is in use, a message is displayed that includes the following:
JIT enabled: jitc
If the JIT is not in use, the following message is displayed:
JIT disabled
IBM does not support the Native Method Interface in this release. Do not use this interface in your applications.
The Java Native Interface (JNI) is included with the Runtime Environment. For information about using the JNI, see the following Sun Web site:
After you install the Runtime Environment for Linux, edit your shell script and add to your PATH statement the following directories:
The Java Plug-in is a Web browser plug-in for use with Netscape Communicator for Linux. If you use the Java Plug-in, you can bypass your Web browser's default Java Virtual Machine and use instead a Java Runtime Environment (JRE) for running applets or beans in the browser.
To install and configure the Java Plug-in:
Note: The first time you start Netscape after you copy the
javaplugin.so file into
the netscape/plugins directory, Netscape will immediately shut down.
(If you started Netscape from the command line, a
Bus error
message is displayed.) You can safely ignore
this message because Netscape will not
encounter this error after the first time.
Java is able to display all Unicode characters, but most versions of Linux install only the fonts needed to show your language. You can download fonts from IBM that allow you to see the complete Unicode character set. These fonts are not included in the Runtime Environment for Linux package because they are large and not all users need them. IBM supplies two Unicode fonts, and each of them is customized by country. Users in China and Korea should use the country specific versions, and all others should use the Japanese version of these fonts.
If you did not download fonts, you can get them from the DeveloperWorks Web site at http://www.ibm.com/developer/java/ where you download the IBM Developer Kit for Linux, Java 2 Technology Edition, Version 1.3.0. Descriptions of the fonts are provided to help you decide which fonts to download.
To install a font, put the file in the /opt/IBMJava2-13/jre/lib/fonts directory.
If you download fonts in parts, you must first put the fonts back together into one file for each font.
To put a font file back together, be sure the file is in the /opt/IBMJava2-13/jre/lib/fonts directory and use the cat command.
For example, if you downloaded the Times New Roman MT30 font in parts, type the following command to put it back together:
cat tmrmt30.t01 tmrmt30.t02 > tmrmt30.ttf
There is an incompatibility in the glibc package used by Caldera eServer 2.3; this might cause Java applications to hang when you compile or run a Java application or applet on Caldera eServer 2.3. To download and install an updated version of glibc, see the following Caldera Systems, Inc. Web site:
The process you use to remove the Runtime Environment for Linux depends on whether you installed the installable RPM package or the compressed TAR package. See Uninstalling the installable RPM package or Uninstalling the compressed TAR package for instructions.
To uninstall the Runtime Environment for Linux if you installed the installable RPM package:
rpm -qa | grep IBMThe name of the package is displayed.
rpm -e pkgnamewhere pkgname is the name of the package that was displayed.
To uninstall the Runtime Environment for Linux if you installed the compressed TAR package:
The Runtime Environment for Linux can be invoked from a shell prompt by using the java tool.
java [-options] classname <args>
The classname argument is the name of the class file to be executed. Any arguments to be passed to the class must be placed after the classname on the command line.
java -jar [-options] jarfile <args>
The jarfile argument is the name of the jar file to be executed. Any arguments to be passed to the jar file must be placed after the jarfile on the command line.
Options for the java tool are as follows:
The -X options are non-standard and subject to change without notice.
To obtain the IBM build and version number, type the following at a shell prompt:
java -version
To take advantage of the euro symbol support, the operating system must support the euro symbol. This might require that you install standard ISO-8859-15 (Latin-9 or Latin-0). For further information, see the HOWTO for your distribution of Linux.
The following sections give further information on euro symbol support.
The Unicode character for the euro is u'20ac'.
Collation of currency symbols traditionally follows the English collation order of the symbol name. Thus cent is followed by dollar. According to this scheme, the euro symbol sorts immediately following the dollar and dong currency symbols and before the French franc.
On double-byte character set (DBCS) systems, if you want to switch the input method, you must set an environment variable that represents the keycode you use for switching. Optionally, you can set another environment variable that represents the modifiers of the keycode.
To specify the keycode to use for switching, set the IBMJAVA_INPUTMETHOD_SWITCHKEY environment variable to a keycode definition in the java.awt.event.KeyEvent class, for example, VK_F4.
Optionally, specify modifiers of the keycode. To specify modifiers of the keycode, set the IBMJAVA_INPUTMETHOD_SWITCHKEY_MODIFIERS environment variable to some combination of the following three mask definitions in the java.awt.event.InputEvent class:
Separate the masks by commas.
For example you might set the IBMJAVA_INPUTMETHOD_SWITCHKEY_MODIFIERS environment variable to ALT_MASK, CTRL_MASK.
During Java initialization, the two environment variables are stored.
To be sure you have set the environment variables correctly, press a key and check it with the key combination you specified. If it matches, a Java pop-up menu with selectable input methods is displayed.
The following Sun Web page might contain a "Hello World" example that you can download. The example demonstrates how to create a simple Java application that runs on and is bundled with the Runtime Environment for Linux. You might find the example at the Sun Web site:
The example shows how to make a simple, seamless transition from developing an application with the Developer Kit for Linux, to deploying it with the more lightweight Runtime Environment for Linux.
After you develop your product and are ready to ship, you need to install your product onto an individual user's system, configure the user's system to support your software, and configure the runtime environment.
If you use the Runtime Environment for Linux, you must make sure that your installation procedure does not overwrite an existing installation (unless the existing Runtime Environment for Linux is an older version).
To redistribute the Runtime Environment for Linux, you can install it on your own system, then copy the required Runtime Environment files into your installation set. If you choose this approach, you must include all the files provided with the Runtime Environment for Linux. The Runtime Environment for Linux software can only be redistributed if all files are included. In effect, when you ship your application, it has its own copy of the Runtime Environment for Linux.
For specific information about the files that must be redistributed, see the license agreement that accompanies this product.
IBM supplies the following runtime documentation:
There is an incompatibility in the glibc package used by Caldera eServer 2.3; this can cause Java applications to hang when you compile or run a Java application or applet on Caldera eServer 2.3. To resolve the problem, you must update the glibc package that is available from the Caldera Support Web site. See Updating the glibc on Caldera eServer 2.3 for instructions.
export LC_ALL="POSIX"
The maximum number of threads available is determined by the minimum of the following:
However, you might run out of virtual storage prior to reaching the maximum number of threads. Additional information about adjusting these limits might be available at the following Web site:
On the Linux X Window System, the keymap is set to: 64 0xffe9 (Alt_L) 0xffe7 (Meta_L), and 113 0xffea (Alt_R) 0xffe8 (Meta_R). You can check this by typing the following at a shell prompt:
xmodmap -pk
This is why the Runtime Environment for Linux considers that Meta is being pressed together with Alt. As a workaround, you can remove the Meta_x mapping by typing the following at a shell prompt:
xmodmap -e "keysym Alt_L = Alt_L" -e "keysym Alt_R = Alt_R"
Note: This workaround might affect other X Windows applications running on the same display if it uses the Meta-key that was removed.
If you are using OpenLinux e-Server 2.3, Japanese version, you must reset some environment variables as follows:
export CLASSPATH= export JAVA_HOME=
If you are using Red Hat Linux 6.2, Japanese version, and you have not downloaded IBM TrueType fonts, halfwidth Katakana characters are not displayed correctly. This is due to the lack of font data for those characters. To use halfwidth Katakana characters, download the IBM TrueType fonts.
If you are running a Java applet using the Java Plug-in with Netscape Communicator and you pass a Japanese string as a parameter value, the parameter value is not passed correctly.
On TurboLinux 6.0J Workstation, you might receive an error message about the libnsfix-ja.so library when using Netscape Communicator.
To fix the problem, rename the file /usr/lib/netscape/libnsfix-ja.so. The new file name is:
On Japanese versions of Linux, you can use a Japanese input method such as Canna, ATOK12(TM) SE, Wnn4(TM), or Wnn6. Use the following sections to avoid problems when using these Japanese input methods.
For all input method editor (IME) users
To bring another window to the top, do one of the following:
Canna users
If you are using the Canna input method with the kinput2 input method server, some visual feedback from the input method is not visible while you are in KIGOU input mode. To avoid the problem, move the focus onto the client window after the Auxiliary Control Window opens.
ATOK12 SE users
Wnn4 users
If you are using Wnn4, the Enter key does not create a new line and a carriage return while the Input Method Editor (IME) is activated. To create a new line and carriage return, deactivate the IME.
Wnn6 users
The xwnmo Input Method server is not supported. Use kinput2 as the Input Method server.
Wnn4, Wnn6 or Canna users
If you are using kinput2 as the Input Method server, do not minimize or maximize the Java window in which the kinput2 lookup window is displayed.
This edition applies to the IBM Runtime Environment for Linux, Java 2 Technology Edition, Version 1.3.0 and to all subsequent releases and modifications until otherwise indicated in new editions.
Copyright International Business Machines Corporation 2000. All rights reserved.
Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
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