关于rails上的ruby：无法安装RMagick gem

Cannot install RMagic gem

我想安装RMagic gem，我得到了"找不到Magick-config"，所以我安装了

1	$ sudo apt-get install libmagickwand-dev

但现在我得到以下输出：

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

/usr/local/rvm/rubies/ruby-2.1.5/bin/ruby -r
./siteconf20150526-12203-xr9xf7.rb 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... *
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/local/rvm/rubies/ruby-2.1.5/bin/ruby extconf.rb:154:in ``': No such file or directory - convert
(Errno::ENOENT)
from extconf.rb:154:in block in
'
from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/mkmf.rb:918:inblock
in checking_for'
from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/mkmf.rb:351:in block
(2 levels) in postpone'
from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/mkmf.rb:321:inopen'
from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/mkmf.rb:351:in block
in postpone'
from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/mkmf.rb:321:inopen'
from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/mkmf.rb:347:in
postpone'
from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/mkmf.rb:917:in
checking_for'
from extconf.rb:151:in `'

extconf failed, exit code 1

Gem files will remain installed in
/usr/local/rvm/gems/ruby-2.1.5@rails4/gems/rmagick-2.13.4 for
inspection. Results logged to
/usr/local/rvm/gems/ruby-2.1.5@rails4/extensions/x86_64-linux/2.1.0/rmagick-2.13.4/gem_make.out

有人可以帮我解决吗？