On OSX and linux it seems to be fairly common practice to totally define the PATH in a
.profile or .bashrc file. This gives total control over the order in which
various locations are searched through. Here’s the line from my .profile:
export PATH=~/bin:/usr/local/bin:/usr/bin:/usr/sbin:/bin:/sbin
However, your PATH isn’t just set through profile and rc files: if you
don’t build your path from scratch and you only ever append or prepend to it
with statements like export PATH=$PATH:some/other/stuff then the OS helpfully
sets your base PATH to something sensible.
It does this based on various files in /etc (at least on OSX):
/etc/paths
This contains the list of the various binary directories which make up the core of your path:
/usr/local/bin
/usr/bin
/bin
/usr/sbin
/sbin
/etc/paths.d
This contains a number of files which contain paths for various applications,
again with one path element per line. I believe these are added to the end of
the PATH. Mine includes a git file:
/usr/local/git/bin