Some time ago I have installed many applications on my Red Hat 8.0 box using the
./configure ...(options)
make
make test
make install

Even if this can seem a silly question: how can I know now which were the options I used in my ./configure command for a determined application?

Thank you all!!!

That's virtually impossible. You could check a lot of them manually though. Do a ./configure --help and then see what all the options are. You can check each one seperatly then. To check installed locations is an easy one. Optional things which you have compiled in or use of libraries are harder. But you could check the executable with ldd to see which libraries it needs. Might give you a few clues.
The best thing to do however is to keep a log on how you compiled things. I have an lfs system so I compile everything from source. I write a small text file for each package I compile with the options I used and any other extra things I had to do to get it working.

You could hae a look at files like config.cache, config.log, etc in the source directory where you built the apps. They should be able o help you out.

As someone already noted, it's quite difficult to figure out after the fact which configure options you used. You could save the config.cache off to the side and rerun configure until you generate a new that matches the saved on.

To keep a package being built consistently from one release to the next, I keep a small script just above the build directory that I used to invoke the configure command. In that script I have all the options that I use to build the package. Then when I build from the sources, I just go into the top of the source tree and enter comthing like ``../configure postgresql'' and away it goes. Six months later when a new version is released, I untar the sources and can use the same configure options as I did the last time by merely rerunning the script. Of course, you have to make sure that none of the configure options' syntax have changed. Having these scripts around is a godsend when it comes time to rebuild Apache + PHP + PostgreSQL.

Try it.

Yup. no better way than saving your config options in a file and running it. What I usually do is..
./configure --help > config.nxny && chmod 755 config.nxny && vi config.nxny
and edit the file to keep the options I want, provide values etc, save and run.

And when the installs directory tree grows out of hand, I run a simple shell script that 'snarfs' the config files renames it to some meaningful name before i wipe the installs tree.

say if the script finds, installs/net/security/OpenSSL-0.97-beta3/config.nxny, picks up that file and renames it to something like..
~/configs/net_security_OpenSSL-0.97-beta3_config.nxny

I know the PHP engine shows complie time options via <?=phpinfo(1)?>, but you knew that already.