java-wrappers - capacities shared by java wrapper scripts
Most Java programs are not run directly, but through small shell
scripts that take care of various things, such as finding a suitable
java environment and looking for libraries.
To ease the task of the maintainers, they rely on a library providing
runtime detection, library detection and other features. This manual
page describes the common features of all those scripts, and to which
point you can configure them. This is mainly done via environment
java-wrappers understands some environment variables:
The java command that will be run. If this variable is set, it
disables all lookup for a java runtime.
Specifies a directory that will be looked for a java or a jdb
executable (depending on the setting of JAVA_DEBUGGER). It has
precedence over JAVA_HOME but not over JAVA_CMD.
A path to a java runtime. If this variable is set, all lookup
for a java runtime is disabled, except that if no java
executable is found in the path, the command java is used.
A probably more easy-to-use version of the JAVA_HOME variable:
instead of specifying the full path of the java runtime, you
name it. List of available flavors can be found in the file
/usr/lib/java-wrappers/jvm-list.sh. See examples below.
If this is set, the wrapper will try to pick up a java debugger
rather than a java interpreter. This will fail if the jbd of the
runtime found is a stub.
Additional classpath, will have priority over the one found by
Additional arguments to the java command. They will come before
all other arguments.
If this variable is set, it will be the only classpath. You’d
better know what you are doing.
This is probably the most important variable; if it set, the
wrapper will print out useful information as it goes by its
business, such as which runtime it did find, and which command
is run eventually.
The path where the wrappers will go looking for jar archives. If
not set, the wrapper will look into the default directory,
/usr/share/java. Warning : the wrapper will not look anywhere
else than in JAVA_JARPATH. Setting it incorrectly will most
probably result in early crashes.
The examples all rely on rasterizer(1), from the package libbatik-java,
but they really apply to all scripts that use java-wrappers.
Print out debugging information:
Limit rasterizer’s memory to 80 MB:
Force rasterizer to run with kaffe(1):
The same, but using JAVA_BINDIR:
Force rasterizer to run with openjdk:
Debug rasterizer with Sun’s debugger, while printing debugging
information from the wrapper:
DEBUG_WRAPPER=1 JAVA_CMD=/usr/lib/jvm/java-6-sun/bin/jdb rasterizer
Care has been taken to make the wrappers bug-free. If that was not the
case, please file a bug report against the java-wrappers package.
If you wish to submit any problem with a java executable relying on
java-wrappers, please also submit the output of the command run with
DEBUG_WRAPPER=1. It will save one mail exchange and therefore
potentially reduce the time it takes to fix the bug.
There is currently no documentation about writing a wrapper script save
the comments in /usr/lib/java-wrappers/java-wrappers.sh. If you have
to write one, we suggest you base yourself upon, for instance, the
rasterizer wrapper script, or any other one (just pick up any direct
reverse dependency of java-wrappers and look for scripts).
java-wrappers and its documentation were written by Vincent Fourmond