Using a UNIX shell script to run a Java program (packaged in a JAR)

Question

Hi,
I have an application (very small) that connects to our database. It needs to run in our UNIX environment so I've been working on a shell script to set the class path and call the JAR file. I'm not making a lot of progress on my own. I've attached the KSH (korn shell script) file code.
Thanks in advance to anyone who knows how to set the class path and / or call the JAR file.
loggedinuser="$(whoami)"
CFG_DIR="`dirname $0`"
EXIT_STATUS=${SUCCESS}
export PATH=/opt/java1.3/bin:$PATH
OLDDIR="`pwd`"
cd $PLCS_ROOT_DIR
java -classpath $
EXIT_STATUS=$?
cd $OLDDIR
echo $EXIT_STATUS
exit $EXIT_STATUS

Answer 1

Hi,
I have an application (very small) that connects to
our database. It needs to run in our UNIX environment
so I've been working on a shell script to set the
class path and call the JAR file.
#!/bin/sh
exec /your/path/to/java -cp your:class:paths:here -MoreJvmOptionsHere your.package.and.YourClass "$@"Store this is a file of any name, e.g. yuckiduck, and then change the persmissions to executechmod a+x yuckiduckThe exec makes sure the shell used to run the script does not hang around until that java program finishes. While this is only a minor thing, it is nevertheless infinite waste, because it does use some resources but the return on that investment is 0.
CFG_DIR="`dirname $0`"You would like to fetch the directory of the installation out of $0. This breaks as soon as someone makes a (soft) link in some other directory to this script and calls it by its soft linked name. Your best bet if you don't know a lot of script programming is to hardcode CFG_DIR.
OLDDIR="`pwd`"
cd $PLCS_ROOT_DIRVery bad technique in UNIX. UNIX supports the notion of a "current directory". If your user calls this program in a certain directory, you should assume that (s)he does this on purpose. Making your application dependent on a start in a certain directory ignores the very helpful concept of 'current directory' and is therefore a bug.
cd $OLDDIRThis has no effect at all because it only affects the next two lines of code and nothing else. These two lines, however, don't depend on the current directory. In particular this (as the cd above) does not change the current directory for the interactive shell your user is working in.
echo $EXIT_STATUS
exit $EXIT_STATUSEchoing the exit status is an interesting idea, but if you don't do this for a very specific purpose, I recommend not to do this for the simple reason that no other UNIX program does it.
Harald.