Hi pb,
WHY is all that junk in there?
As usual, the answer depends partly on what level of "why" you are asking about. For example, at a fairly superficial level, a typical application install puts a number of different kinds of files onto your system. Man pages normally reside in a fairly small number of places and the man application needs to know where to look for them. Some systems, e.g. Solaris, typically use a MANPATH environment variable to find all the man pages you might want to use. The Fedora box sitting under my desk does not have a MANPATH variable, but does have several "man" directories where man does find its pages. I'm not sure where it keeps track of them, but I doubt that it would automatically find man pages in, say, /usr/local/foo/man/1 without help. Even on the Solaris boxes I run, I doubt that I'd want to add each application's man pages to my MANPATH. Similar considerations apply to LD_LIBRARY_PATH and others. The administration of how man or the linker or loader or various other functions can find their files becomes a lot easier if the files those functions need are in a relatively small number of places.
So, the "--libdir=/usr/lib" part is there because the loader is going to need to know where the libraries are. /usr/lib is an obvious default location, but you could choose to override that for various reasons.
Alternatively, you might be asking why /usr/lib should be an obvious default location and the answer to that is historical rather than (strictly speaking) logical. Basically, the /usr part of the directory tree was intended for the "user" of the computer (i.e., the sysadmin) to install stuff that wasn't originally part of the OS. By now, there is a lot of stuff that wasn't originally part of the OS that didn't originally come with a Unix(-like) OS, so the entire /usr directory subtree is rather poorly named.
On another hand, another level of "why" might be "why should all of this stuff be configurable?" And that basically is because there are some pretty non-standard systems around. If you normally take the defaults, then your life is going to be a lot simpler than the folks who put stuff in really odd places. But the PHP folks are at least trying to allow you to put things in the odd places. For example, one of my (by now
mostly former) responsibilities is a 64-node Linux cluster. Each node has its own system disk, but they all share the /home filesystem, which is NFS mounted to all the nodes. This means that a lot of the stuff that all the nodes need can actually sit on the /home filesystem with symlinks from places like /usr/local. Much of that software requires being situated in /usr/local/something, but in order to turn a nightmare into a lesser nightmare (a nightfoal?) I used those symlinks to allow a single copy of the software across the cluster. Something that allows itself to reside painlessly in /home/local/bin is a real blessing in cases like this.
But if your question was really rhetorical and soliciting commiseration rather than information, you do have my sympathy. :)
Best Regards,
Paul
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