首先，必須安裝ImageMagick

bower install ImageMagick

Building native extensions.  This could take a while...
ERROR:  Error installing rmagick:
    ERROR: Failed to build gem native extension.

/usr/bin/ruby extconf.rb
checking for Ruby version >= 1.8.5... yes
checking for gcc... yes
checking for Magick-config... yes
checking for ImageMagick version >= 6.4.9... yes
checking for HDRI disabled version of ImageMagick... yes
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
checking for stdint.h... yes
checking for sys/types.h... yes
checking for wand/MagickWand.h... no

Can't install RMagick 2.13.1. Can't find MagickWand.h.
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/bin/ruby
 

ImageMagick一般路徑:

/usr/local/lib/pkgconfig/MagickCore.pc

如果不對，可以用mdfind

mdfind MagickCore.pc

找到pkgconfig的路徑:

/usr/local/lib/pkgconfig

安裝gem時設定路徑

PKG_CONFIG_PATH=/usr/local/lib/pkgconfig gem install rmagick

也可以將PKG_CONFIG_PATH寫入profile

vi ~/.bash_profile
PKG_CONFIG_PATH=/usr/local/lib/pkgconfig
export PKG_CONFIG_PATH
 

gem install rmagick