Dynamic Link of a Shared Library at Application Start-up

A small modification to the previous example enables a shared application to load a shared library dynamically.

Loading a Shared Library Dynamically

1. Create the shared library file.

   Copy the libdyn.c file into the libshareddir directory and rename it libshared.c. The ensuing Imakefile will build a PIC binary object file called libshared.o and a shared library named libshared.so as follows:

   FPIC = ON
   SRCS = libshared.c
   SharedLibraryTarget (libshared.so, libshared.o, , , , )
   Depend($(SRCS))

2. Create the shared program file.

   Copy the progdyn.c file into the progshareddir directory and rename it progshared.c. The ensuing Imakefile will build a PIC binary object file called progshared.o and an executable file called progshared:

   FPIC = ON
   SRCS = progshared.c
   LIBPATH = <pathname of the shared library directory>
   SharedUserTarget (progshared_u, progshared.o,
      $(UTILS_LIB) $(CLX_UTILS_LIB), -L$(LIBPATH)
      -Xlinker -rpath -Xlinker/shared -lshared,,)
   Depend($(SRCS))

3. Copy the shared application.

   Copy the shared application into the /bin subdirectory of the chorus_root_directory directory:

   % cp $WORK/progshareddir/progshared_u chorus_root_directory/bin

4. Copy the shared library.

   Copy the shared library into the /shared subdirectory of the chorus_root_directory directory:

   % cp $WORK/libshareddir/libshared.so chorus_root_directory/shared

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   Note -

   There is no need to set LD_LIBRARY_PATH as the path for the runtime linker. This path was specified in the Imakefile by setting the -Xlinker -rpath option.

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5. Start the application.

   The following command starts the application and loads the libshared.so and libc.so libraries (if they have not already been loaded by another application):

   % rsh jericho /bin/progshared_u