install rmagick '2.13.2' gem - checking for Magick-config... no

IF you get a Magick-config error while installing 2.13.2 then rmagick couldn't find imagemagick while installing.

first make sure you have pkg-config

brew update
brew doctor

brew install pkg-config
brew unlink pkg-config && brew link pkg-config

run which pkg-config to find where its installed, usually its installed at /usr/local/bin/pkg-config

export it as PKGCONFIGPATH:

export PKG_CONFIG_PATH="/usr/local/bin/pkg-config" 

Make sure you have ImageMagick and know which version you're running.

brew install imagemagick
brew unlink imagemagick && brew link imagemagick
# NOTE YOUR VERSION

export this path:

C_INCLUDE_PATH="/usr/local/Cellar/imagemagick/[version]/include/ImageMagick-6"

find libtool

ls /usr/local/Cellar/libtool/
=> 2.4.4

Export these paths:

LDFLAGS="-L/usr/local/Cellar/libtool/[version]/lib"

CPPFLAGS="-I/usr/local/Cellar/libtool/[version]/include" 

The final exports should have looked something like this:

export C_INCLUDE_PATH="/usr/local/Cellar/imagemagick/6.9.0-3/include/ImageMagick-6"

export LDFLAGS="-L/usr/local/Cellar/libtool/2.4.4/lib"

export CPPFLAGS="-I/usr/local/Cellar/libtool/2.4.4/include" 

now install the rmagick:

gem install rmagick -v '2.13.2'