Does anybody have a reference to what the various path names mean on different flavors of Unix? Please include Solaris, RHEL, and SLES in the list if possible.
e.g. From what I have gathered /lib is standard libraries for the distribution, which never change (is this correct? or do they get new versions from time to time?), /usr/local is for apps installed by the sysadmin, etc. But I am not sure that this is correct and I'm still unclear about the difference between /usr/lib and /lib (the former is for sysadmin installed libraries?) and /sbin and /bin and so on... Thanks.
Most Linux distributions follow the Filesystem Hierarchy Standard FHS (at least mostly). Big parts of it are simply rules that have been true for UNIX for quite some time (/usr, /var, ...), others are rather new (/media, ...).
One thing that I found confusing initially is the existence of both /bin and /usr/bin as well as /lib and /usr/lib with a seeemingly random distribution of where stuff goes. The reasoning behind this split is that /usr might be mounted from a different storage (possible remote) than the root so /bin and /lib should contain a minimal system that is enough to get the whole system up and running in the event of some system failure.
So Gnome, GIMP and so on can go in /usr, as they are not essential, but filesystem-tools such as fsck and mkfs as well as the shell sh need to reside in the non-usr directories.