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FAQ Manager is guru Nathan Meyers PREMIUM.

Java on Linux is gaining popularity as a powerful and capable server and client platform. Learn what's available for Linux, and how to install and use Java in the Linux world.

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How can I limit the size of a growing logfile Java creates on Linux? Can I have a file that "loses" data at the beginning to keep it from growing past a certain size?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Jan 8, 2002
Files don't work that way, but you can rotate logs to keep the size under control. You have a couple of ways to do that easily: The log4j package...

What is the thread limit in Sun's jdk1.3 on Linux?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Dec 27, 2001
The limit on native threads comes from the system, not from Java. See this FAQ entry for a discussion of managing thread limits. There is no limit on...

Can I have Java Web Server on Linux?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Dec 20, 2001
According to Sun's Java Web Server FAQ: No. There is no supported version of Java Web Server for Linux, but there are customers who have successfully...

What are the hardware requirements for running a servlet environment on Linux with Apache, Tomcat, and PostregSQL?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Dec 15, 2001
It depends entirely on the application. Most Linux software doesn't publish hardware requirements, which are usually fictions anyway. You can get a development...

The javac compiler is slow and expensive - I need a way to optimize for my application. I'm trying to run a Java compiler as a response to a POST to a Web site (users submit programs to compile) - but...
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Dec 13, 2001
The javac compiler doesn't have any such daemon mode, but here are a couple of suggestions: Use the Jikes compiler from IBM. It's open source, written...

Can I run a JDK under FreeBSD?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Dec 2, 2001
Yes. Ports of the Sun JDK for FreeBSD are published at this site.

Can I cut, copy, and paste between AWT and other X applications under Linux?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Dec 2, 2001
Yes - sometimes it's easy, and sometimes not. X has two commonly used mechanisms for copying and pasting between applications, which can be a bit conf...

What's the difference between the "client" and "server" virtual machines in JDK1.3 and later?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Nov 15, 2001
They both use the HotSpot performance engine, but the server VM optimizes aggressively up-front for the benefit of long-term performance, while the client...

Can I increase the number of file descriptors my app can support by increasing the number of threads? Since every thread on Linux is a process, and every process allows a certain number of file descriptors,...
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Oct 31, 2001
No. It's true that every thread takes an entry from the pid table. But they are still threads, not heavyweight processes, and the same file descriptor...

How to pass values containing spaces using Runtime.exec(command)? There doesn't seem to be any way to include a space character within an argument.
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Oct 24, 2001
Use the Runtime.exec(String[]) call, with each argument in its own element of the string array. This is what Java does, under the covers, after separating...

Why do applets that look good under Netscape/Windows look terrible under Netscape/Linux? The layout doesn't work, the text fields are too small to contain the text, etc.
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Oct 2, 2001
This usually happens with applets that have been carefully laid out to look good in Windows. For better or worse, the AWT doesn't specify much about what...

Why has the -Xnoagent option gone away in JDK1.3.1?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Sep 21, 2001
That option is only meaningful with a JVM running green threads. JDK1.3.1 only ships a HotSpot JVM running native threads.

How can I identify the top-level thread of a Java process?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Sep 21, 2001
Because each thread has a separate PID that shows up in ps and top output, it's difficult to figure out which is the top-level process. Two possible ways...

How can I generate native code instead of classfiles from my Java source?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Sep 13, 2001
The two best-support answers are: The gcj compiler is part of the GNU compiler collection and can be found in any recent distribution of gcc. It builds...

How do I run Java programs from a crontab entry?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Aug 24, 2001
Processes run by crontab are owned by the user who created the crontab entry, but they don't inherit the user's login environment - including the PATH...

How do java.lang.Runtime.totalMemory() and freeMemory() relate to values reported by top and other tools? In particular, why do Java processes use so much memory (according to top) above the limit set...
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Aug 16, 2001
The correspondence between total process memory usage and the numbers reported by the heap memory manager is not very close. There are a couple of reasons...

How do I run a Java program as a daemon on Linux?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Aug 9, 2001
A daemon usually means some service that is started up and run persistently when the system boots or enters a certain init state. There are standard...

How do I use Unix pipes with Java?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Jul 30, 2001
Java doesn't give you direct access to non-portable capabilities like Unix/Linux pipes. You can still do quite a few things with pipes, for example: Create...

How can I run a remote program using Runtime.exec()? For example, I'd like to launch a remote program on a Linux box from Windows.
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Jul 30, 2001
Runtime.exec() runs programs locally, just as if you'd typed the command into a command shell. On a Linux box, it's as if you'd typed the command into...

Why can't a servlet find class sun/awt/X11GraphicsEnvironment on a Solaris server?
Platform:UNIX:Linux
Nathan Meyers PREMIUM, Jul 20, 2001
Any use of the AWT requires access to an X server - even if you are not creating any windows. A couple of ways to handle it are: Run a virtual-frame-buffer...

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Related Links

Linux Forum

The Blackdown Organization - porting Java for multiple Linux platforms

Sun's JDK1.2.2 for Linux

IBM's JDK1.3 for Linux

Kaffe - a cleanroom Java implementation

gcj - the Gnu Compiler for Java

Java Programming on Linux (book by FAQ manager)

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