Ubuntu14.04にNokogiriを導入する

rubyを導入する

sudo add-apt-repository -y ppa:brightbox/ruby-ng
sudo apt-get update
sudo apt-get -y install ruby2.1

この状態で
sudo gem install nokogiri
すると、下記のエラーが出る。

ERROR:  Error installing nokogiri:
        ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h

extconf failed, exit code 1

よって、解決するために

コンパイルに必要な環境を整える

sudo apt-get install ruby2.1-dev

この状態で
sudo gem install nokogiri
すると、下記のエラーが出る。

ERROR:  Error installing nokogiri:
        ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb
checking if the C compiler accepts ... yes
Building nokogiri using packaged libraries.
checking for gzdopen() in -lz... no
zlib is missing; necessary for building libxml2
*** 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
        --curdir
        --ruby=/usr/bin/ruby2.1
        --help
        --clean
        --use-system-libraries
        --enable-static
        --disable-static
        --with-zlib-dir
        --without-zlib-dir
        --with-zlib-include
        --without-zlib-include=${zlib-dir}/include
        --with-zlib-lib
        --without-zlib-lib=${zlib-dir}/lib
        --enable-cross-build
        --disable-cross-build

extconf failed, exit code 1

よって、解決するために

sudo apt-get install zlib1g-dev

とすればよい。最後に

Nokogiriを導入する

sudo gem install nokogiri

として完了。

まとめ

1. sudo add-apt-repository -y ppa:brightbox/ruby-ng
2. sudo apt-get update
3. sudo apt-get -y install ruby2.1 ruby2.1-dev zlib1g-dev
4. sudo gem install nokogiri