Why always ./configure; make; make install; as 3 separate steps?

Question

Every time you compile something from source, you go through the same 3 steps:

$ ./configure
$ make
$ make install

I understand, that it ma

Answer 1

First, it should be ./configure && make && make install since each depends on the success of the former. Part of the reason is evolution and part of the reason is convenience for the development workflow.

Originally, most Makefiles would only contain the commands to compile a program and installation was left to the user. An extra rule allows make install to place the compiled output in a place that might be correct; there are still plenty of good reasons that you might not want to do this, including not being the system administrator, not want to install it at all. Moreover, if I am developing the software, I probably don't want to install it. I want to make some changes and test the version sitting in my directory. This becomes even more salient if I'm going to have multiple versions lying around.

./configure goes and detects what is available in the environment and/or is desired by the user to determine how to build the software. This is not something that needs to change very often and can often take some time. Again, if I am a developer, it's not worth the time to reconfigure constantly. More importantly, since make uses timestamps to rebuild modules, if I rerun configure there is a possibility that flags will change and now some of the components in my build will be compile with one set of flags and others with a different set of flags that might lead to different, incompatible behaviour. So long as I don't rerun configure, I know that my compilation environment remains the same even if I change my sources. If I rerun configure, I should make clean first, to remove any built sources to ensure things are built uniformly.

The only case where the three command are run in a row are when users install the program or a package is built (e.g., Debian's debuild or RedHat's rpmbuild). And that assumes that the package can be given a plain configure, which is not usually the case for packaging, where, at least, --prefix=/usr is desired. And pacakgers are like to have to deal with fake-roots when doing the make install part. Since there are lots of exceptions, making ./configure && make && make install the rule would be inconvenient for a lot of people who do it on a far more frequent basis!