I sometimes install software which isn't present in the repositories, and then I run into the problem of not satisfied dependencies. The error usually tells me which library or command is missing. Then I run a
yum search. If there is a package name coinciding with the library/command name needed, it is easy.
The problem comes when I can't find anything in yum. I start searching around on the Web, and often I find links to the library. But I don't know whether to trust these sites, where to copy the library if I download it, what it is supposed to do at all, and so on. Often it is supposed to be for another distribution, or another Fedora version, and then I don't know whether they will work with mine. I suspect that these libraries are probably present in some package already in the repository, and I would much rather have them from there than from random Googled sites.
How can I find out which package a library belongs to, if I have its name? For example, now I need the library libpng12.so.0, how do I get it? And if it is not a library, but a command, how do I find the package which provides it?