calltest.c is a program that demonstrates how Callable IDL might
be used. This file explains how to build and run it on a Unix platform.

The general approach is the same on all Unix systems: You must compile
the source file (calltest.c) and then link it against the IDL sharable
library and any system libraries required to complete the link. Although
this is straightforward, the details of which libraries to use, and their
locations, differ.

The Unix IDL distribution contains a directory named "bin" that contains
the executables for idl and its related programs. For every supported
operating system / hardware architecture supported by your installation,
you will find a subdirectory containing the platform specific binaries for
that system. For example, platform specific support for Solaris2 running
on Sparc hardware is found in $IDL_DIR/bin/bin.solaris2.sparc. Each of
these directories contains a makefile that shows how to relink IDL. This
makefile also contains a rule to build calltest. To understand how calltest
is built (and therefore how to link other callable IDL programs) you should
read this makefile.


BUILDING CALLTEST:
------------------

   The following instructions include example statements that show how
to build calltest. These examples assume that you have an environment
variable named "IDL_DIR" that points to the root of the IDL installation
of your system, you are running /bin/csh or a compatible shell, and you
wish to build calltest for Solaris2 on Sparc hardware. If your situation
differs, you will need to adjust these statements accordingly:

    (1) Create an empty scratch directory to build calltest in.

		% mkdir ~/calltest
		% cd ~/calltest

    (2) Copy the makefile to your new empty directory.

		% cp $IDL_DIR/bin/bin.solaris2.sparc/Makefile .

    (3) Build calltest.

		% make calltest

    (4) To run calltest on many systems, you will need to add the
        IDL architecture specific bin directory to your dynamic library
        search path. Under most Unixes, this is LD_LIBRARY_PATH. Under AIX
        it is LIBPATH, and under HP-UX it is SHLIB_PATH.

		% setenv LD_LIBRARY_PATH \
		         $IDL_DIR/bin/bin.solaris2.sparc:$LD_LIBRARY_PATH

    (5) Run it.

		% ./calltest