Why is plenv install-cpanm installing to the wrong location?

Question

Something wacky happened with my plenv setup and I haven't gotten my head around it.

plenv install-cpanm
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!
! Can't write to /Library/Perl/5.18 and /usr/local/bin: Installing modules to /Users/olaf/perl5
! To turn off this warning, you have to do one of the following:
!   - run me as a root or with --sudo option (to install to /Library/Perl/5.18 and /usr/local/bin)
!   - Configure local::lib in your existing shell to set PERL_MM_OPT etc.
!   - Install local::lib by running the following commands
!
!         cpanm --local-lib=~/perl5 local::lib && eval $(perl -I ~/perl5/lib/perl5/ -Mlocal::lib)
!
App::cpanminus is up to date. (1.7042)

$ plenv which cpanm
plenv: cpanm: command not found

$ find /Users/olaf | grep bin/cpanm
/Users/olaf/.cpanm/work/1482416411.97013/App-cpanminus-1.7042/bin/cpanm
/Users/olaf/.cpanm/work/1482416863.23085/App-cpanminus-1.7042/bin/cpanm
/Users/olaf/perl5/bin/cpanm

$ find /Users/olaf/.plenv | grep cpanm
/Users/olaf/.plenv/libexec/plenv-install-cpanm
/Users/olaf/.plenv/plenv.d/rehash/rehash_cpanm.bash

I would expect cpanm to get installed somewhere inside of ~/.plenv, but that's just not happening. I'm guessing something in my dot files/shell setup/$ENV is messed up?

This is what my $ENV looks like:

env | grep PLENV
PLENV_SHELL=bash

Also, the beginning of my PATH is:

PATH=/Users/olaf/.plenv/shims:/Users/olaf/.plenv/bin

Answer 1

I got this sorted with some help from Tatsuhiko Miyagawa. It turns out that I had switched to the system Perl via plenv and had expected it to handle module installs in the same way that it works for Perls which plenv installs for you. The solution was just to choose a version of Perl which I had installed earlier via plenv (plenv local 5.24.0) and then to plenv install-cpanm. Tatsuhiko Miyagawa also pointed out that I'll need to install-cpanm for each version of Perl that I have installed.