Rick Moen <rick@???> wrote:

>> With a lib, is there any code or is it *JUST* a set of symbols ?

> This is a pretty good introduction to how libraries work and what they
> can contain:
> http://www.skyfree.org/linux/references/ELF_Format.pdf


Thanks, a bit heavy going for me at this time in the morning !

> Generically, a library can do just about anything, potentially. A
> library is simply a set of compiled program routines that the get called
> by executables (call to function dlopen) that invoke particular
> functions within the libraries, and access symbols (call to function
> dlsym). To know what's inside a _specific_ library, you need to look at
> that library's source code.

OK, that's what I thought, which is at odds with some comments that have been made.
So basically, if I have a subsystem "foobar" and a library "libfoobar0", and in that library I have a call called "init_foobar" then that call could do :
At one extreme, just recognise that foobar isn't installed and return a code to indicate that.
At the other extreme, do a whole load of stuff, even if foobar itself isn't installed - basically anything up to and including forking a persistent process ?

Yes, the latter wouldn't make much sense, but it's possible ?