Hi folks,

I've been using Linux more or less exclusively for about 4 years. In that time I've developed what I feel is, on the whole, a pretty solid level of user (as opposed to developer) knowledge. I can compile my own kernels, install stuff, write scripts and all that happy stuff. However, I am thoroughly embarrased by how little I understand about the whole subject of libraries, archives, linking, etc. At a basic level I think I understand the prinicipal of what a shared library is and why it's a good thing, but beyond that I am kind of clueless about how it all fits together and what commands like ld, ldconfig, ar, etc do and when one needs to use them.

For example, today I installed dosemu. When I tried to run it, it complained that it couldn't find libXxf86vm.so.1. Now, for kicks I looked around and I've found that there is a file libXxf86vm.a in /usr/X11/lib, but as expected no libXxf86vm.so.anything. I gather the .a file is an "archive" file, but I don't really understand what that is. Is it related to the .so file I am apparently missing? Can I somehow create the .so file from what I have already on my machine? If not, how would I go about figuring out where I have to go to get the right lib file?

I've looked around here and elsewhere for some kind of a primer on the whole library subject, but without any luck.

So, can one of you kind souls either give me a nickel-and-dime tour of the subject, or point me to a good reference where I can get a handle on it all?

Thanks in advance,

Dave

The .a is a reference to a.out, an older form of binary executable file which has been replaced by ELF format. A.out is maintained for backward compatibility. You don't say which distro you're using or how old (new?) it is. You may need to upgrade libXxf86 to get the ELF binaries. Or, try to find a statically-linked dosemu with ELF binaries included. Or, try an aout2elf conversion utility. Copy the libX....a file you have, convert to ELF, and give it the correct .so.1 extension and see it that works (I wouldn't bet money on it).
Google turns up loads of discussion on the topic of a.out and ELF.