Interpreters installed via pyenv are not added to $PATH

I can't figure out why pyenv (installed via homebrew) doesn't seem to work.

It seems like my $PATH variable isn't updated correctly by pyenv and therefore none of the interpreters installed via pyenv can be found. For example, for python version 3.6.8:

$ pyenv versions
  system
* 3.4.10 (set by /Users/cglacet/.pyenv/version)
* 3.5.7 (set by /Users/cglacet/.pyenv/version)
* 3.6.8 (set by /Users/cglacet/.pyenv/version)
* 3.7.3 (set by /Users/cglacet/.pyenv/version)
* 3.8-dev (set by /Users/cglacet/.pyenv/version)

$ pyenv which python3.6
/Users/cglacet/.pyenv/versions/3.6.8/bin/python3.6

$ $(pyenv which python3.6) --version
Python 3.6.8

$ pyenv shell
pyenv: no shell-specific version configured

$ pyenv local
pyenv: no local version configured for this directory

Up until here everything looks just fine, but:

$ python3.6 --version
-bash: python3.6: command not found

$ python --version
Python 3.7.0

If I check my PATH environment variable, I can't see any path of the form /Users/cglacet/.pyenv/versions/3.x.x/bin.

Note that 3.7.0 is the python version I had before installing pyenv (the system one). What I expect is to have 3.6 available (all versions installed via pyenv), which should be the case as I activated it as a global interpreter as shown before. The expected behavior is:

$ python3.6 --version
Python 3.6.8

Solution

After a bit of digging I found that homebrew install failed to edit my .bash_profile. The problem is that pyenv itself doesn't rely on these additions and therefore the bug is silent (you just don't have the interpreters in your path).

If you are in this case you'll have to run part of the install manually (starting at "#2 Configure your shell's environment for Pyenv" and add the following in your ~/.bash_profile (preferably append this new path so it arrives before your system python path, in other word, append this at the end of your bash profile):

export PATH=$(pyenv root)/shims:$PATH

That solves the problem I had (as the directory $(pyenv root)/shims contains all the interpreters you installed via pyenv). But you might want to have the complete set of features that pyenv offers (eg., autocompletion of commands), which (in theory) could be done by adding the following to your .bash_profile instead of the PATH export:

eval "$(pyenv init -)"

But for me that didn't work as pyenv init produced some faulty code (missing function declaration), on the other hand you can use the following and it should work (better):

eval "$(pyenv init - | sed 's:^pyenv() :function pyenv():')"

I still have no idea why the installation failed on my system, if anyone as a clue that would be interesting (and that would probably deserve a fix because I probably won't be the only one having this issue).