Using Brew to Install rbenv

I'm trying to take a coursera class on Ruby from Johns Hopkins. The Mac OSX set up instructions require that I download homebrew and then install rbenv. I already have brew installed from stuff I had done a long time back, so perhaps this issue is because I screwed up installing ruby/brew a long time ago.

Here's the command that's giving me issues: brew install rbenv ruby-build the response i get is this:

Warning: rbenv-0.4.0 already installed, it's just not linked ==> Installing dependencies for ruby-build: pkg-config, openssl Error: Cannot link pkg-config Another version is already linked: /usr/local/Cellar/pkg-config/0.28 

Update: Here's what appeared after running brew doctor:

Warning: /usr/local/bin isn't writable. This can happen if you "sudo make install" software that isn't managed by Homebrew. If a formula tries to write a file to this directory, the install will fail during the link step. You should probably change the ownership and permissions of /usr/local/bin back to your user account. sudo chown -R $(whoami) /usr/local/bin Warning: /usr/local/share isn't writable. This can happen if you "sudo make install" software that isn't managed by Homebrew. If a formula tries to write a file to this directory, the install will fail during the link step. You should probably change the ownership and permissions of /usr/local/share back to your user account. sudo chown -R $(whoami) /usr/local/share Warning: Some directories in /usr/local/share/man aren't writable. This can happen if you "sudo make install" software that isn't managed by Homebrew. If a brew tries to add locale information to one of these directories, then the install will fail during the link step. You should probably `sudo chown -R $(whoami)` them: /usr/local/share/man /usr/local/share/man/man1 /usr/local/share/man/man5 /usr/local/share/man/mann Warning: Broken symlinks were found. Remove them with `brew prune`: /usr/local/bin/2to3-3.3 /usr/local/bin/apm /usr/local/bin/atom /usr/local/bin/idle3.3 /usr/local/bin/python3.3-32 /usr/local/bin/pythonw3 /usr/local/bin/pythonw3-32 /usr/local/bin/pythonw3.3 /usr/local/bin/pythonw3.3-32 /usr/local/bin/pyvenv-3.3 /usr/local/bin/subl Warning: Python is installed at /Library/Frameworks/Python.framework Homebrew only supports building against the System-provided Python or a brewed Python. In particular, Pythons installed to /Library can interfere with other software installs. Warning: Unbrewed dylibs were found in /usr/local/lib. If you didn't put them there on purpose they could cause problems when building Homebrew formulae, and may need to be deleted. Unexpected dylibs: /usr/local/lib/libMonoPosixHelper.dylib /usr/local/lib/libSFFileMonitor.32.dylib /usr/local/lib/libSFIPC.32.dylib /usr/local/lib/libSFIPC.I.dylib /usr/local/lib/libSFsqlite3.7.4.dylib /usr/local/lib/libSFSyncEngine.I.dylib /usr/local/lib/libtcl8.6.dylib /usr/local/lib/libtk8.6.dylib Warning: Unbrewed header files were found in /usr/local/include. If you didn't put them there on purpose they could cause problems when building Homebrew formulae, and may need to be deleted. Unexpected header files: /usr/local/include/fakemysql.h /usr/local/include/fakepq.h /usr/local/include/fakesql.h /usr/local/include/itcl.h /usr/local/include/itcl2TclOO.h /usr/local/include/itclDecls.h /usr/local/include/itclInt.h /usr/local/include/itclIntDecls.h /usr/local/include/itclMigrate2TclCore.h /usr/local/include/itclTclIntStubsFcn.h /usr/local/include/mysqlStubs.h /usr/local/include/node/ares.h /usr/local/include/node/ares_version.h /usr/local/include/node/nameser.h /usr/local/include/node/node.h /usr/local/include/node/node_buffer.h /usr/local/include/node/node_internals.h /usr/local/include/node/node_object_wrap.h /usr/local/include/node/node_version.h /usr/local/include/node/openssl/opensslconf.h /usr/local/include/node/uv-private/ngx-queue.h /usr/local/include/node/uv-private/stdint-msvc2008.h /usr/local/include/node/uv-private/tree.h /usr/local/include/node/uv-private/uv-bsd.h /usr/local/include/node/uv-private/uv-darwin.h /usr/local/include/node/uv-private/uv-linux.h /usr/local/include/node/uv-private/uv-sunos.h /usr/local/include/node/uv-private/uv-unix.h /usr/local/include/node/uv-private/uv-win.h /usr/local/include/node/uv.h /usr/local/include/node/v8-debug.h /usr/local/include/node/v8-preparser.h /usr/local/include/node/v8-profiler.h /usr/local/include/node/v8-testing.h /usr/local/include/node/v8.h /usr/local/include/node/v8stdint.h /usr/local/include/node/zconf.h /usr/local/include/node/zlib.h /usr/local/include/odbcStubs.h /usr/local/include/pqStubs.h /usr/local/include/tcl.h /usr/local/include/tclDecls.h /usr/local/include/tclOO.h /usr/local/include/tclOODecls.h /usr/local/include/tclPlatDecls.h /usr/local/include/tclThread.h /usr/local/include/tclTomMath.h /usr/local/include/tclTomMathDecls.h /usr/local/include/tdbc.h /usr/local/include/tdbcDecls.h /usr/local/include/tdbcInt.h /usr/local/include/tk.h /usr/local/include/tkDecls.h /usr/local/include/tkPlatDecls.h Warning: Unbrewed .pc files were found in /usr/local/lib/pkgconfig. If you didn't put them there on purpose they could cause problems when building Homebrew formulae, and may need to be deleted. Unexpected .pc files: /usr/local/lib/pkgconfig/tcl.pc /usr/local/lib/pkgconfig/tk.pc Warning: Unbrewed static libraries were found in /usr/local/lib. If you didn't put them there on purpose they could cause problems when building Homebrew formulae, and may need to be deleted. Unexpected static libraries: /usr/local/lib/libtclstub8.6.a /usr/local/lib/libtkstub8.6.a Warning: You have unlinked kegs in your Cellar Leaving kegs unlinked can lead to build-trouble and cause brews that depend on those kegs to fail to run properly once built. Run `brew link` on these: rbenv Warning: You have uncommitted modifications to Homebrew If this is a surprise to you, then you should stash these modifications. Stashing returns Homebrew to a pristine state but can be undone should you later need to do so for some reason. cd /usr/local/Library && git stash && git clean -d -f Warning: /usr/bin occurs before /usr/local/bin This means that system-provided programs will be used instead of those provided by Homebrew. The following tools exist at both paths: 2to3 2to3-2.7 easy_install easy_install-2.7 idle idle2.7 info infokey install-info makeinfo pydoc pydoc2.7 python python-config python2.7 python2.7-config pythonw pythonw2.7 smtpd.py smtpd2.7.py tclsh tclsh8.5 texi2dvi texi2pdf texindex wish wish8.5 Consider setting your PATH so that /usr/local/bin occurs before /usr/bin. Here is a one-liner: echo 'export PATH="/usr/local/bin:$PATH"' >> ~/.bash_profile` 

New Update: I did brew prune, changed ownership of the files that it suggested (some of them could not be found). Finally, when i run brew install rbenv ruby-build i get the following errors:

Warning: rbenv-0.4.0 already installed, it's just not linked Warning: ruby-build-20151028 already installed 

The next step would be to do rbenv install 2.2.3, but rbenv command is not found. Seems that the installation failed somehow. which rbenv also produced no output.