Bash script class path issue with java

Question

Content of /opt/scripts/jvm/jvm.script.sh

#!/bin/bash JAVA_HOME='/java' PATH="$PATH:/$JAVA_HOME/bin" java -cp ./classes:./lib com.mystuff.bar.foo.myclass & 

Content of /etc/init.d/init.script.sh

home='/opt/scripts/jvm' program=jvm.script.sh su scriptuser -c "$home/$program" 

/opt/scripts/jvm is symlinked to /data/shellscripts (meaning /data/shellscripts exists as a real directory).

Running the init script fails with cannot find class com.mystuff.bar.foo.myclass but if I su to the same user and run it, it works, why?

When I run su scriptuser -c 'declare -p JAVA_HOME' I get JAVA_HOME not found, but if I su to the user first (using su scriptuser) and run it, I get JAVA_HOME="/java"

This may sound crazy, but it seems to fix the issue if I add a trailing slash to the home variable in the init script.

So:

home='/opt/scripts/jvm' 

becomes

home='/opt/scripts/jvm/' 

It almost seems like something environmental is messing with the way the symlinks are being handled.

Answer 1

It's a confusing question with the paths and su'ing. When you run this command:

$java -cp ./classes:./lib com.mystuff.bar.foo.myclass

And get 'class not found', that means java is not able to find that class in ./classes or ./lib. If you either

a) use absolute paths, or b) cd to the right place before running the command (su scriptuser -c "cd $home ; ./$program")

it will work more reliably.

As for why adding a "/" to home makes a difference, that does seem very strange. You could break out strace/truss and see what system calls the command is making. This answer quotes from the posix spec:

How linux handles multiple path separators (/home////username///file)

and says "For programs that act on a directory entry, if foo is a symbolic link to a directory, then passing foo/ is a way to make the program act on the directory instead of the symbolic link."