Specify soname when creating shared library

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The shared library soname (cont.)

Here's how to use a soname:

2. Specify soname when creating shared library:




$ gcc -fPIC -c -Wall -g mod1.c mod2.c mod3.c 
$ gcc -shared -Wl,-soname,libbar.so -o libfoo.so \
           mod1.o mod2.o mod3.o




3. -Wl,-soname,libbar.so instructs linker to mark the shared library libfoo.so with the sonamelibbar.so.
5. Create executable:




$ gcc -g -Wall -o prog prog.c libfoo.so




6. Linker detects that libfoo.so contains the soname
7. libbar.soand embeds the latter name inside the executable.
9. Run the program:




$ LD_LIBRARY_PATH=. ./prog
./prog: error in loading shared libraries: 
libbar.so: cannot open shared object file: 
No such file or directory




10. Dynamic linker cannot find anything named libbar.so.
12. Create a symbolic link from the soname to the real name of the library:




$ ln -s libfoo.so libbar.so
$ LD_LIBRARY_PATH=. ./prog
Called mod1-x1
Called mod2-x2

At run-time thislink can point to a version of the library which is different from the version against which linking was performed.