Re: Anyone use variables to shorten classpath declaration?
- From: Nigel Wade <nmw@xxxxxxxxxxxx>
- Date: Fri, 02 Feb 2007 09:54:45 +0000
snoopy_@xxxxxxxxxx wrote:
Anyone use variables to shorten classpath declaration? For example,
if I want to point to /opt/myclasses/testpackage.jar, could I do the
following?
update .profile to include
PACKAGE_DIR=/opt/myclasses
CLASSPATH=$PACKAGE_DIR/testpackage.jar
export CLASSPATH
Yes, that will work.
The reason I am asking is because I am trying to troubleshoot an issue
where an application failed to find some jar files, and I found that
one profile sourced another, but the variable it uses as a shortcut
isn't defined at the time the CLASSPATH is defined, however, if I
check the path after all the source files are picked up it looks right
via "echo $CLASSPATH" because I have since defined PACKAGE_DIR.
For example, the definition aboe is switch to look like:
CLASSPATH=$PACKAGE_DIR/testpackage.jar
export CLASSPATH
PACKAGE_DIR=/opt/myclasses
No, that won't work. If you use a variable as part of another variable
definition you get its contents at the time you use it. Try it manually and see
what you get.
Variables don't record that they are dependent on other variables. When you use
one variable in the definition of another all that happens is that the current
value of that variable is inserted. If it has no current value (isn't defined)
then nothing is substituted. Your resulting CLASSPATH will be
"/testpackage.jar". No amount of changing $PACKAGE_DIR after the fact will
alter that.
I know it's a strange question, but I'm pulling out my hair trying to
figure out why we had CLASSPATH issues with our system.
--
Nigel Wade, System Administrator, Space Plasma Physics Group,
University of Leicester, Leicester, LE1 7RH, UK
E-mail : nmw@xxxxxxxxxxxx
Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555
.
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- From: snoopy_@xxxxxxxxxx
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