INSTALL

/*-------------------------------------------------------------------------
|   rxtx is a native interface to serial ports in Java.
|   Copyright 1997-2004 by Trent Jarvi taj@www.linux.org.uk
|
|   This library is free software; you can redistribute it and/or
|   modify it under the terms of the GNU Library General Public
|   License as published by the Free Software Foundation; either
|   version 2 of the License, or (at your option) any later version.
|
|   This library is distributed in the hope that it will be useful,
|   but WITHOUT ANY WARRANTY; without even the implied warranty of
|   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
|   Library General Public License for more details.
|
|   You should have received a copy of the GNU Library General Public
|   License along with this library; if not, write to the Free
|   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
--------------------------------------------------------------------------*/
This is the INSTALL file for RXTX.  Thu Jul  7 19:46:26 EDT 2005

If, while following the instructions, you find this file unclear or incorrect 
please make a note and email the details to taj@www.linux.org.uk.

A note about rxtx 2.1:

rxtx 2.1 replaces the entire CommAPI.  Every effort is made to conform to
CommAPI but out of respect for our friends at Sun the package name of 2.1 has
been moved to gnu.io.  A script is offered in contrib/ChangePackage.sh that
will switch source tree's between javax.comm and gnu.io.

See Sun's CommAPI license for more details on why this decision was made.

If you would like to use javax.comm, use rxtx 1.4 with Sun's CommAPI.

A note on Mac OS X:

	Go to the MacOSX file for install instructions. 

1.  INSTALL INSTRUCTIONS IN OTHER LANGUAGES

	A. Japanese 

2.  BUILDING COMMAPI SUPPORT

	A.  Quick Install
	B.  Uninstalling Sun's comm.jar
	C.  installing javax.comm.properties.
	D.  Add RXTXcomm.jar to your CLASSPATH.
	E.  Build and Install the jar.
	F.  Where did everything end up?
	G.  Compiling for Win32 support

3.  COMMON PROBLEMS

	A.  java.lang.UnsatisfiedLinkError: nSetOwner while loading driver
	    gnu.io.RXTXCommDriver
	B.  Exception in thread "main" java.lang.UnsatisfiedLinkError: 
	    no rxtxSerial in java.library.path
	C.  I Can Not Open the Port.
	D.  java.lang.NoClassDefFoundError: gnu/io/CommPort
	E.  The Compiler Cannot Find Java Include Files
	F.  Configure says 'unterminated sed command' and stops 
	G.  Java Can Not Find libstdc++-libc6.0-1.so.2 
	H.  BlackBox Can Not Handle all the ports!
	I.  Illegal use of nonvirtal function call!
	J.  My libc5 Linux system is generating SIGSEGV
	K.  AM_PROG_LIBTOOL not found in library
	L.  Problems with RMISecurityManager()
	M.  Which Wires Should be Connected?
	N.  Which Device Should be Used?
	O.  It Did Not Work! 
	P.  Which jdk should be used? 
	Q.  How does rxtx detect ports?  Can I override it?
	R.  How can I use Lock Files with rxtx?
	S.  How can I tell which version of rxtx is installed?
	T.  What Type of Latency can I expect with RXTX
	U.  I got rxtx working on a new OS but I can't read from the port
	V.  My ThinkPad is Not Working!

4)  APPLETS

	A.  Using Applets

-------------------------------------------------------------------------------
1.  INSTALL INSTRUCTIONS IN OTHER LANGUAGES
A.  Japanese

	Instructions are available in Japanese at

	The instructions are fairly old but should help.

	http://www.geocities.co.jp/Technopolis/4789/settei.htm#id1
	Thanks to Masayuki "Tencho" Yamashita <tencho@venus.kanazawa-it.ac.jp>
	home page http://www.geocities.co.jp/Technopolis/4789/ 

	A copy of these install instructions is provided in 
	install-japanese.html
	
	We will gladly include instructions in any language provided.  Tencho 
	was the first to contribute instructions in another language.

2.  BUILDING COMMAPI SUPPORT

	The following is concerned with building and installing commapi 
	support with Sun's CommAPI package.  A full stand alone version of 
	rxtx is in the CVS archive for interested developers.

	A.  Quick Install

	The following packages are used to build rxtx:

		autoconf-2.59
		automake-1.9.5
		libtool-1.5.18
		gnu make-3.79.1         On some systems like FreeBSD this is
					called gmake
		jdk 1.3 or newer	

	With the packages installed, proceed to build and install rxtx.

		$ tar -xzvf rxtx-2.1.tar.gz
		$ cd rxtx-2.1
		$ ./configure  (follow the instructions)
		$ make install (gmake if your system uses that convention)
		Read "R.  How can I use Lock Files with rxtx?"

	One catch that has showed up... you cannot have spaces in the path.
	for instance:  /home/jarvi/test build/rxtx/... will cause problems.
                                   ----^
	If that does not work or you do not want a script messing with the 
	system, read on..

	B.  Uninstalling Sun's comm.jar

		Sun's comm.jar is not required.  It is a valid option on
		some platforms.  IT WILL CREATE CHAOS if you have it installed
		while trying to build rxtx 2.1.

		http://java.sun.com/products/javacomm/index.html
		
	C.  Installing javax.comm.properties.

		javax.comm.properties is not currently required by rxtx-2.1

	D.  Add RXTXcomm.jar to your CLASSPATH.

		jdk-1.1:

			make sure /usr/local/java/lib/RXTXcomm.jar is in your
			CLASSPATH.  If you want to use apps that require
			RXTXcomm.jar.

			in bash:

			$ export CLASSPATH=/usr/local/java/lib/RXTXcomm.jar:.

		jdk-1.2 and newer:

			No changes are needed.

	E.  Build and Install the jar.

		configure       configure supports build directories.
				configure requires javac in its path or
				JAVA_HOME set to grab some java system
				properties.
		make    	to build RXTXcomm.jar and the libraries
		make install 	to place the jar and libraries in the correct 
				location

		You may select the JDK you wish to build with using $JAVA_HOME
		For example:
			export JAVA_HOME=/usr/local/java
		Otherwise, configure grabs the JDK from your PATH.

	F.  Where did everything end up?

		Lets assume the top java directory is /usr/local/java

		jdk-1.2 the files go in
		
			/usr/local/java/jre/lib/ext/RXTXcomm.jar
			/usr/local/java/jre/lib/$(ARCH)/librxtxSerial.so.
			/usr/local/java/jre/lib/$(ARCH)/librxtxParallel.so.
			/usr/local/java/jre/lib/$(ARCH)/lib/...

		jdk-1.1.* the files go in 

			/usr/local/java/lib/RXTXcomm.jar
			/usr/lib/librxtxSerial.so.
			/usr/lib/librxtxParallel.so.
			/usr/lib/...

			The librxtxSerial.so librxtxParallel.so are placed in 
			/usr/lib so people don't have to change with their 
			LD_LIBRARY_PATH.

	G.  Compiling for Win32 support

		Get the Sun CommAPI if you want a plug-in solution.  The code 
		is provided for people that may have demanding needs and coding
		ability. 

		There is only serial port code at this time.

		Three ways of compiling win32 libraries are offered:

			mingw32 tools in DOS
			lcc tools in DOS
			cross-compiling from Linux

		----------------- mingw32 tools in DOS -----------------------

		Install mingw32  http://www.mingw.org
		Install a jdk    http://java.sun.com/j2se
		Make sure the ming32\bin and jdk\bin directories are in your
		path.
		In the rxtx top directory to the following:
		mkdir build
		copy Makefile.mingw32 build\Makefile
		cd build
		edit the Makefile and make sure the directories are correct.
		execute the following:
			make
			make install
		
		----------------- lcc tools in DOS ---------------------------

		Install a jdk    http://java.sun.com/j2se
		Install lcc http://www.cs.virginia.edu/~lcc-win32/

		A make file (Makefile.lcc) for compiling rxtx with lcc
		contributed by Valentin Pavlov

		You will need a config.h file in the src directory.  Other
		builds usually generate them automatically.  The following
		should work.

		#define HAVE_FCNTL_H
		#define HAVE_SIGNAL_H
		#undef HAVE_SYS_FCNTL_H
		#undef HAVE_SYS_FILE_H
		#undef HAVE_SYS_SIGNAL_H
		#undef HAVE_TERMIOS_H
		#undef HAVE_SYS_TIME_H

		if you know how to create the above in a dos Makefile send in			the changes.

		the following commands should then work fine on the command
		line.

		cd src
		make -f ..\Makefile.lcc

		----------------- cross-compiling from Linux -----------------

		Grab ming32:

		Wayne Roberts contributed the version used by the maintainer.
		(Wayne is largely responsible for bringing rxtx back to win32.)
		http://www.linuxgrrls.org/~taj/crossmingw32-2.95-1.i386.rpm
		A more current version can be obtained:
		http://www.devolution.com/~slouken/SDL/Xmingw32/crossgcc/index.html
		prebuilt Binaries:
		http://www.devolution.com/~slouken/SDL/Xmingw32/mingw32-linux-x86-glibc-2.1.tar.gz

		I built the dll with jdk-1.2.2 for linux using jdk-1.2.2 
		include files from the win32 JDK.

		Make sure that ming32 bin dir is the first in your path (at 
		least before /usr/bin/gcc)

			$ export PATH=" \
				/usr/local/cross-tools/i386-mingw32/bin/: \
				$PATH:/usr/X11R6/bin:/usr/local/java/bin: \
				/usr/local/java/jre/bin/:"

		Place Sun jdk 1.2.2 win32 include files in a known location.

			$ mkdir /home/jarvi/win32java
			$ cp -r /mnt/win98//java/include /home/jarvi/win32java

			If you are developing win32 support you may want to
			export the location to make the config script
			non interactive

			$ export WIN32INCLUDE=/home/jarvi/tools/win32-include

		run configure to generate a Makefile

			$ cd /home/jarvi/rxtx-*
			$ mkdir build
			$ cd build
			$ ../configure --target=i386-mingw32  \
				--host=i386-redhat-linux

		build the class files and dll.

			$ make

		the files will be located in

			rxtx-*/build/...

		If you're looking at rxtx as an example of cross-compiling you 
		may be interested in looking at the examples provided at:

			ftp.xraylith.wisc.edu
			/pub/khan/gnu-win32/mingw32/misc/java-jni-examples.zip

3.  COMMON PROBLEMS

A.  I get java.lang.UnsatisfiedLinkError: nSetOwner while loading driver
    gnu.io.RXTXCommDriver when using rxtx.

	SetOwner appears to be some win32 call.
	Do not use Sun's win32 CommAPI files.  Get the Solaris version.
	"javacomm20-x86.tar.Z" and rxtx-1.4 if you want Sun's solution.

	See Also: 2-B.  Installing Sun's comm.jar (IE its not needed at all)

B.  Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial in 
    java.library.path

	librxtxSerial.so is located in the wrong directory.  Here is an example

	$ mv /usr/local/java/jre/lib/i386/librxtxSerial* /usr/local/lib
	$ java BlackBox
	Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial
	in java.library.path
		at java.lang.ClassLoader.loadLibrary(Compiled Code)
		at java.lang.Runtime.loadLibrary0(Compiled Code)
		at java.lang.System.loadLibrary(Compiled Code)
		at gnu.io.NativePort.<clinit>(NativePort.java:32)
		at gnu.io.RXTXPort.<init>(Compiled Code)
		at gnu.io.RXTXCommDriver.getCommPort(Compiled Code)
		at gnu.io.CommPortIdentifier.open(Compiled Code)
		at SerialPortDisplay.openBBPort(Compiled Code)
		at SerialPortDisplay.<init>(Compiled Code)
		at BlackBox.addPort(Compiled Code)
		at BlackBox.main(Compiled Code)

		... lets fix it.

    Solution 1: move the file to a place that works

         $ mv /usr/local/lib/librxtxSerial.* /usr/local/java/jre/lib/i386/

    Solution 2: add the location of librxtxSerial to LD_LIBRARY_PATH

         $ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib/

    Solution 3: pass the location in on the command line

         $ java -Djava.library.path=/usr/local/lib/ ...

C.  I Can Not Open the Port.

	If you're not able to open the port (read the errors carefully) then you 
	may not have permission to use the device.  Redhat Linux ships with the
	following permissions:

	crw-r--r--   /dev/ttyS?

	Users need to be able to read and write with serial communication...

	chmod 666 /dev/ttyS? 

	should fix the problem.  Be sure to check the file CommAPI for common 
	mistakes.

	Make sure that the user can create lock files see R.

D.  java.lang.NoClassDefFoundError: gnu/io/CommPort

	RXTXcomm.jar is probably not in your classpath or not located in
	the proper directory.

	for example, lets not include RXTXcomm.jar

	export CLASSPATH=../java/lib/classes.zip
	$ java BlackBoxException in thread "main"
	java.lang.NoClassDefFoundError: gnu/io/CommPort

E.  The Compiler Cannot Find Java Include Files

	Check to top of the Makefile to make sure we agree on the location of
	the include files that came with the jdk.  Specifically:

	JAVAINCLUDE =  -I /usr/local/java/include/
	JAVANATINC =  -I /usr/local/java/include/genunix
	also check the classpath
	CLASSPATH = ...

F. Configure says 'unterminated sed command' and stops 

	Unterminated sed command errors usually result from `find` producing 
	unexpected results.   If you are unsure remove all comm.jar and 
	configure to place in in the correct place. 

G.  Java Can Not Find libstdc++-libc6.0-1.so.2 

	jdk-1.2 on redhat systems may note that Java complains about not being
	able to find libstdc++-libc6.0-1.so.2.  A symbolic link can be used to 
	get around this feature.

	ln -s /usr/lib/libstdc++ /usr/lib/libstdc++-libc6.0-1.so.2
	ls -l /usr/lib/libstdc++-libc6.0-1.so.2
 	/usr/lib/libstdc++-libc6.0-1.so.2 -> libstdc++.so.2.8.0

H.  BlackBox Can Not Handle all the ports!

	BlackBox has a hard coded limit in BlackBox.java that prevents it from 
	running if you don't specify a port.  We are considering alternative 
	ways of handling the large number of port names in Unix.  The line in 
	question

	is:

		portDisp = new SerialPortDisplay[50];
		
	just change 50 to say 256.

I.  Illegal use of nonvirtal function call!

	Exception in thread "main" java.lang.VerifyError: (class: 
	gnu/io/RXTXPort$SerialOutputStream, method: flush signature: ()V) 
	Illegal use of nonvirtual function call
		at gnu.io.RXTXCommDriver.getCommPort(Compiled Code)
		at gnu.io.CommPortIdentifier.open(Compiled Code)
		at SerialPortDisplay.openBBPort(Compiled Code)
		at SerialPortDisplay.<init>(Compiled Code)
		at BlackBox.addPort(Compiled Code)
		at BlackBox.main(Compiled Code)

	"1.1 compilers sometimes generate code that won't verify under 1.2.

	If you don't have the sources for the offending class to recompile with
	a 1.2 javac, the only solution I know of is to launch the VM with the
	-noverify option.

	Louis"

	In other words start with a fresh build directory, rebuild, and 
	reinstall to avoid the problem.

J.  My libc5 Linux system is generating SIGSEGV

	Older Linux Systems (libc5) should upgrade to a glibc system with 
	libpthread-0.7 or newer.  We have run into many problems with older 
	libraries.  SIGSEGV was the most common symptom.  Reported by  Peter 
	Bennett <bencom@bencom.co.nz>

K.  AM_PROG_LIBTOOL not found in library

	cd. && aclocal
	aclocal:configure.in: 23: macro 'AM_PROG_LIBTOOL' not found in library
	make:***[aclocal.m4]Error 1

	If you're positive things are setup right you may try the autogen.sh 
	script to try regenerating the scripts with your tools.

L.  Problems with RMISecurityManager()

	Please see the file RMISecurityManager.html 

M.  Which Wires Should be Connected?

	With the DB25 use 2 (TX), 3 (RX) and 7 (GD) to connect to the device.
	With the DB9  use 2 (RX), 3 (TX) and 5 (GD) to connect to the device.

	You will need to hook up more than that for hardware flow control.

N.  Which Device Should be Used?

	Linux serial ports should use /dev/ttyS?
	specialx, cyclades and isdn4 linux have been reported to work.
	as many as 64 ports have worked at one time.
        FreeBSD uses cuaa?
	netbsd uses tty0?
	Irix  uses ttyd? ttym? ttyf?
	HP-UX uses tty0p? tty1p?
	BeOS uses /dev/ports/serial?
	Win32 uses COM?
  
O.  It Did Not Work! 

	There are sure to be bugs.  The goal is to make the install as painless
	as possible.  Send back comments if something could be easier.

	If you run into a problem building the rxtx package please include the
	output generated by the following script.

        ---------------clip-----------------
#!/bin/sh
which java
java -version
uname -a
autoconf --version
automake --version
libtool --version
make --version
        ---------------clip-----------------

	Here's what's on my system for comparison.  Older make is known to cause
	problems.

		java 1.4
		autoconf-2.53
		automake-1.6.3
		libtool-1.4.2
		gnu make-3.79.1  

	mail any bugs to taj@www.linux.org.uk.

P.  Which jdk should be used? 

	Ideally any jdk would be fine.  Here is a list of jdk's tried on
	RedHat 6.0/kernel 2.2.17pre13 with various versions of glibc.

                 Sun            IBM           Blackdown
                 2.1.2_006      1.3.0         1.1.8v1
                 green  native  green native  green native
                 ------------------------------------------
glibc-2.1.1-6   | OK   | *1   | *2   | *2   | OK   | *3   |
                -------------------------------------------
glibc-2.1.2-11  | OK   | *1   | OK   | OK   | OK   | OK   |
                -------------------------------------------
glibc-2.1.2-17  | OK   | *1   | OK   | OK   | OK   | OK   |
                -------------------------------------------
glibc-2.1.3-15  | OK   | *1   | OK   | OK   | OK   | OK   |
                -------------------------------------------

1)  BlackBox (a demo application shipped with CommAPI locks after multiple 
    open()/close()

2) java wont start "Unable to load /usr/local/java/jre/bin/libhpi.so: symbol
sem_wait, version GLIBC_2.1 not defined in file libpthread.so.0 with link time
reference Could not create the Java virtual machine."

3) java wont start "error in loading shared libraries:
/usr/local/java/bin/../lib/i686/native_threads/libjava.so: symbol sem_init,
version GLIBC_2.1 not defined in file libpthread.so.0 with link time reference"

Conclusion?  Avoid Sun's native threads unless you can figure out whats going
wrong.
 
Q.  How does rxtx detect ports?  Can I override it?

rxtx tries to detect ports on by scanning /dev for files matching any
of a set of known-good prefixes, such as 'ttyS', 'ttym', and so on.
Any ones that exist, are supposed to be good for the current operating
system, and that can be read and written are offered back from
CommPortIdentifier.getPortIdentifiers(), and only these can be used as
ports.

If you wish, you can set the system properties gnu.io.rxtx.SerialPorts
and gnu.io.rxtx.ParallelPorts.  If either of these is set, then no
scanning will be carried out and only the specified ports will be
available.  You can use this to make one platform look like another,
to restrict Java access to ports, or possibly for other reasons.  For
example

	java -Dgnu.io.rxtx.SerialPorts=/dev/cua/a:/dev/cua/b com.foo.MyApp

will look kind of like Solaris, if you have created the appropriate
device nodes.

A note on Linux port enumeration.  We have set most ports aside.  Once the
number of possible devices started getting into the thousands, checking them
all made little sense.  Look in RXTXCommDriver.java and search for Linux.

You will see that only /dev/ttyS* is searched but the possible addition ports
that can be used are listed under it.  Just copy the few you need.

R.  How can I use Lock Files with rxtx?

Redhat users.  Note that Redhat changed group uucp to group lock with Redhat
7.2.

Mandrake users.  Note that /var/lock needs to be group uucp for this to work.

Mac OS X users.  Note that you may need to create the lock directory with group uucp ownership.  There is a script in contrib called fixperm.sh to help with
this on Mac OS X.

RXTX uses lock files by default.  configure --disable-lockfiles to generate
rxtx libraries without lock files.  Its strongly recommended that you do
use lock files to prevent rxtx from stomping on other programs using serial
ports.

Lock files are used to prevent more than one program accessing a port at a
time.  Lock files require a bit of sysadmin to work properly..

Rxtx has support for lock files on Linux only.  It may work on other
platforms but read the source before blindly trying it. 

Before you use lock files you need to do one of two things:

	1.  Be the root or uucp user on your machine whenever you use rxtx
	2.  add the specific user that needs to use rxtx to the group uucp.
	    (preferred)

To add a user to the uucp group edit /etc/group as root and change the 
following:
	uucp::14:uucp
to something like:
	uucp::14:uucp,jarvi
In this case jarvi is the login name for the user that needs to use lock files.
Do not change the number (14).  Whatever is in your group file is correct.

User jarvi in this case can now use rxtx with lock files.

The lock file code does not support kermit style lock files or lock files in
/var/spool.  Its sure to fail if you're using subdirectories in /dev or do not
have /dev.

	Still cant get things to run under a root account?

	Vadim Tkachenko writes:
	
	"Maybe you remember - couple of months back I've run into inability to
	run the JDK 1.3+ from under root account.

	Today, absolutely suddenly, something clicked in my head and the cause
	was found: libsafe. To make JDK work, it is enough to disable libsafe
	(unset LD_PRELOAD)."

As another option it is possible to use a Lock File Server.  In this case,
a server runs in group uucp or lock and rxtx then connects to localhost
to lock and unlock the port.  The server and install instructions can be
found in src/lfd.  RXTX will need to be configured to use the server:

	configure --enable-lockfile_server

Any user can then lock the ports if they are not already locked.

S.  How can I tell which version of rxtx is installed?

Version information is not documented in Sun's CommAPI so this is probably
unique to RXTX.

As of rxtx-1.5-4 and rxtx-1.4-6 a class has been added to allow developers to 
check which version of rxtx is installed.  The class is RXTXVersion.  

The static method: System.out.println(RXTXVersion.getVersion());

will print the rxtx version as a String in the following format:

        "RXTX-MAJOR.MINOR-PATCH".

an example would be:

        "RXTX-1.5-4"

A change in the MAJOR version would suggest you're in trouble.

Odd MINOR version are reserved for development.  Even MINOR versions are
reserved for 'stable' releases.

PATCH is used to differentiate incremental releases of the MINOR releases.

CommPortIdentifier is expected to support getVersion() in the RXTX-1.5 series.

T.  What Type of Latency can I expect with RXTX

	frantz <fcapiez@club-internet.fr> put RXTX under a scope and found
	the following:

	RXTX currently has a latency of 150-200ms on a PII at 450mhz.
	The latency can be reduced to 70-80ms by reducing the usleep()
	value in SerialImp.c:eventLoop() to usleep(5000)).

	Much lower latencies should be possible but the maintainer does not
	have equipment to test changes.

	He is going to look at this further.  He needs 20 ms or less latency.
	
U.  I got rxtx working on a new OS but I can't read from the port

> Now my java program starts up nicely without complaining. However, it does
> never read any data from the serial port. It looks like it can write data,
> because if I start a terminal program after I tried to run my program, I get
> all the return stuff from the modem that my program wrote.
> 
> I hacked around abit and found out that it hangs in the select() call which
> simply never returns.
> 
On Sun, 28 Jan 2001, Baldur Norddahl wrote:
> HPUX 11:
> 
> As I wrote to the mailinglist I had some wierd problems where it apparently
> could write data to the modem, but not read anything back. My terminal
> programs had no problem using the port. A few days after I reported the
> problem to the mailinglist, I had given up for now, but then I noticed that
> it suddenly worked! So it remains a mystery what was wrong as I did not
> change anything at all, neither in my program nor on the host.
> 
> Baldur
> 

I suspect two java applications had the port open.  Its easy to do while 
developing.  Perhaps <ctl> z instead of <ctl> c was entered.

This is the reason for adding lockfile support to rxtx.  If another application
has opened the port, a second application will appear to not be able to 
read or get only part of the data.  ..because the first one is reading.  Only
one of the select()s are waken.

Its possible to put lockfile support in for HPUX if it is known where other
applications place their lockfiles.   The easiest way to find out where is
to fire up minicom, kermit, ... and see where its lockfile is placed.

Here are the known suspects:

const char *lockdirs[]={ "/etc/locks", "/usr/spool/kermit",
                "/usr/spool/locks", "/usr/spool/uucp", "/usr/spool/uucp/",
                "/usr/spool/uucp/LCK", "/var/lock", "/var/lock/modem",
                "/var/spool/lock", "/var/spool/locks", "/var/spool/uucp",NULL
        };

freebsd uses /var/spool/uucp/, linux uses /var/lock those are the only two
I've done so far.  Adding the support is trivial once a directory is
decided upon.

Lockfiles are rather simple.  when an application opens a port it first checks
if there is a file with the ports name.  If there is it grabs the PID from the
file.  If that PID is still active the application does not open the port.

If the PID is not active or there is no lockfile, the application creates one
with its own PID in it.

The confusion starts when you have to decide where (see above) to put the
lockfile, what the name format is for the file and how to store the PID.

rxtx follows The File System Hierarchy Standard http://www.pathname.com/fhs/
on linux.  I'm not positive what is normal on other OS's.

                more reading:

                The File System Hierarchy Standard
                http://www.pathname.com/fhs/

                FSSTND
                ftp://tsx-11.mit.edu/pub/linux/docs/linux-standards/fsstnd/

                Proposed Changes to the File System Hierarchy Standard
                ftp://scicom.alphacdc.com/pub/linux/devlock-0.X.tgz

                "UNIX Network Programming", W. Richard Stevens,
                Prentice-Hall, 1990, pages 96-101.
                more reading:

V.  My ThinkPad is Not Working!

	Scott Burleigh <Scott.Burleigh@jpl.nasa.gov> writes:

		For your files, and in case anybody asks in the 
		future, IBM Thinkpads ship with the external serial port
		*disabled* by default.  The Thinkpad configuration utility
		supplied with the machine (under Windows) says it's enabled,
		and the device manager in the System dialog of the Control
		panel says it's enabled, but they lie.  In order to enable the
		port you have to use the old DOS ps2.exe bios configuration 
		utility which, under Windows 2000, is in
		c:\Program Files\Thinkpad\utilities:

			ps2 sera enable

		Until you do, "setserial -ga /dev/ttyS0" will always tell you
		the UART is unknown.  



4.  APPLETS

More info is needed on signing applets.  This is an exchange from the rxtx mail-
list.

A.  Using Applets

prashantg10@yahoo.com asked:

	Hi All !

	I am trying to use applet on thin terminal which has
	Linux base Kernel.For testing I am using Linux
	machine.I have install all the required components.
	e.g. JDK, RXTX. Everthing is fine. BlackBox runs ,even
	my application runs. When It comes to applet,
	everything is halts. It does not even show the listing
	of ports. Is it because applet can't run under root
	account or what might be the reasons. Can anybody tell
	me solution.

Son To <son@openbx.net> replied:

	Java applets run withing the sandbox of the security manager.
	Applets must be signed to access the com port, but for development 
	purposes you can put

	user_pref("signed.applets.codebase_principal_support", true);

	in your prefs.js located in ~/.mozilla/default/XYYrandomDirName
	
	I didn't use Java applet for my application. I used XUL and CSS for
	the GUI development and used mozilla Javascript SOAP library to
	communicate with apache Axis webservice backend which uses RXTX to
	access the com port.

-- 
Trent Jarvi
taj@www.linux.org.uk
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reminder:

redhat 7.1 needs:
export LD_ASSUME_KERNEL=2.2.5