I am trying to install astrolog. The bit linked to as the source files seems to be for windows, so I'm using ast54unx.shr. I did $sh ast54unx.shr into a directory called astrolog, and tried to do $make but it keeps coming back with errors, different ones, but the current one after commenting out some lines in astrolog.h according to this post is
'/usr/bin/ld: cannot find -lX11
collect2: ld returned 1 exit status
make: *** [astrolog] Error 1'

How should I install it?

I also have a general question about installing things from source: if I unpack and make them in a folder in my home folder, do they stay there/need to stay there, or do they get copied to /usr/bin or somewhere allowing me to delete the folder?

This error usually means you don't have the libX11.so library installed on your system. Which distribution are you running on? On my OpenSuse 11.1 the shared library /usr/lib/libX11.so is provided by the package xorg-x11-libX11-devel but it can be different for other distributions.

Regarding your second question, you can compile the source code in any place then copy the executable somewhere in your path. /usr/local/bin/ is a good choice. Take in mind that the installation of astrolog is atypical: it just build the executable and leave it in the current directory. It's up to you to copy it in a directory included in your PATH.

On the other end, the most common method to install from source requires three steps:
and the latter usually copies (installs) the compiled files in the proper locations, but always depending on the choice of the developers. They should be /usr/bin, /usr/lib, /usr/share/man, etc. or /usr/local/bin, /usr/local/lib, /usr/local/share/man, etc. However you can take control of the installation directories using the --prefix option in the configure step.

Furthermore, as a general rule it's safer to not delete the source directory, unless you have problems with disk space. This is because if you decide to uninstall the software, you can usually do
from the source directory itself, and every file copied in the installation process is removed from the system. Anyway, as I stated above, the astrolog installation does not follow these rules.

I'm running Fedora 11. I googled and installed libX11-devel, and ... it worked! While I was still wondering why yum wouldn't install libX11-devel, though (it did on the second try), I found that there is a deb of astrolog for ubuntu and that a program called alien can convert these to rpm — is this a good way of installing software, and if it is, where do I get alien, as yum can't find it?

It would be okay to move it though, wouldn't it (it doesn't need to be in the same place to find the files to uninstall)?

That's really useful information on my second question.

I used alien twice to install two packages for which I couldn't find the RPM and it worked good. I've always installed alien from source. Here is the official site: http://kitenet.net/~joey/code/alien/.
Correct. The uninstall process uses full paths.