我正在尝试练习ruby。当我尝试安装nokogiri时，我得到了这个错误。我正在学习教程。
Building native extensions. This could take a while...
ERROR: Error installing nokogiri:
ERROR: Failed to build gem native extension.
current directory: /usr/local/rvm/gems/ruby-2.3.0/gems/nokogiri-1.6.8/ext/nokogiri
/usr/local/rvm/rubies/ruby-2.3.0/bin/ruby -r ./siteconf20161001-91233-6vj1dy.rb extconf.rb
Using pkg-config version 1.1.7
checking if the C compiler accepts -ggdb3 -O0 -std=c11 -Wall -Werror -Wshadow... yes
Building nokogiri using packaged libraries.
Using mini_portile version 2.1.0
checking for gzdopen() in -lz... yes
checking for iconv... yes
************************************************************************
IMPORTANT NOTICE:
Building Nokogiri with a packaged version of libxml2-2.9.4.
Team Nokogiri will keep on doing their best to provide security
updates in a timely manner, but if this is a concern for you and want
to use the system library instead; abort this installation process and
reinstall nokogiri as follows:
gem install nokogiri -- --use-system-libraries
[--with-xml2-config=/path/to/xml2-config]
[--with-xslt-config=/path/to/xslt-config]
If you are using Bundler, tell it to use the option:
bundle config build.nokogiri --use-system-libraries
bundle install
Note, however, that nokogiri is not fully compatible with arbitrary
versions of libxml2 provided by OS/package vendors.
************************************************************************
Extracting libxml2-2.9.4.tar.gz into tmp/x86_64-pc-linux-gnu/ports/libxml2/2.9.4... OK
Running 'configure' for libxml2 2.9.4... OK
Running 'compile' for libxml2 2.9.4... ERROR, review '/usr/local/rvm/gems/ruby-2.3.0/gems/nokogiri-1.6.8/ext/nokogiri/tmp/x86_64-pc-linux-gnu/ports/libxml2/2.9.4/compile.log' to see what happened. Last lines are:
========================================================================
CC entities.lo
CC encoding.lo
encoding.c:491:26: error: cast from 'const unsigned char *' to 'unsigned short *' increases required alignment from 1 to 2 [-Werror,-Wcast-align]
unsigned short* in = (unsigned short*) inb;
^~~~~~~~~~~~~~~~~~~~~
encoding.c:573:27: error: cast from 'unsigned char *' to 'unsigned short *' increases required alignment from 1 to 2 [-Werror,-Wcast-align]
unsigned short* out = (unsigned short*) outb;
^~~~~~~~~~~~~~~~~~~~~~
encoding.c:729:26: error: cast from 'const unsigned char *' to 'unsigned short *' increases required alignment from 1 to 2 [-Werror,-Wcast-align]
unsigned short* in = (unsigned short*) inb;
^~~~~~~~~~~~~~~~~~~~~
encoding.c:815:27: error: cast from 'unsigned char *' to 'unsigned short *' increases required alignment from 1 to 2 [-Werror,-Wcast-align]
unsigned short* out = (unsigned short*) outb;
^~~~~~~~~~~~~~~~~~~~~~
4 errors generated.
make[2]: *** [encoding.lo] Error 1
make[2]: Leaving directory `/usr/local/rvm/gems/ruby-2.3.0/gems/nokogiri-1.6.8/ext/nokogiri/tmp/x86_64-pc-linux-gnu/ports/libxml2/2.9.4/libxml2-2.9.4'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/usr/local/rvm/gems/ruby-2.3.0/gems/nokogiri-1.6.8/ext/nokogiri/tmp/x86_64-pc-linux-gnu/ports/libxml2/2.9.4/libxml2-2.9.4'
make: *** [all] Error 2
========================================================================
*** 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-2.3.0/bin/$(RUBY_BASE_NAME)
--help
--clean
--use-system-libraries
--enable-static
--disable-static
--with-zlib-dir
--without-zlib-dir
--with-zlib-include
--without-zlib-include=${zlib-dir}/include
--with-zlib-lib
--without-zlib-lib=${zlib-dir}/lib
--enable-cross-build
--disable-cross-build
/usr/local/rvm/gems/ruby-2.3.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:366:in `block in execute': Failed to complete compile task (RuntimeError)
from /usr/local/rvm/gems/ruby-2.3.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:337:in `chdir'
from /usr/local/rvm/gems/ruby-2.3.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:337:in `execute'
from /usr/local/rvm/gems/ruby-2.3.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:111:in `compile'
from /usr/local/rvm/gems/ruby-2.3.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:150:in `cook'
from extconf.rb:364:in `block (2 levels) in process_recipe'
from extconf.rb:257:in `block in chdir_for_build'
from extconf.rb:256:in `chdir'
from extconf.rb:256:in `chdir_for_build'
from extconf.rb:363:in `block in process_recipe'
from extconf.rb:262:in `tap'
from extconf.rb:262:in `process_recipe'
from extconf.rb:555:in `<main>'
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/usr/local/rvm/gems/ruby-2.3.0/extensions/x86_64-linux/2.3.0/nokogiri-1.6.8/mkmf.log
extconf failed, exit code 1
Gem files will remain installed in /usr/local/rvm/gems/ruby-2.3.0/gems/nokogiri-1.6.8 for inspection.
Results logged to /usr/local/rvm/gems/ruby-2.3.0/extensions/x86_64-linux/2.3.0/nokogiri-1.6.8/gem_make.out
怎么了?任何帮助都是感激的。我试着寻找解决方法，但没有一个方法对我有用。
编辑:我使用的是ubuntu 14.04和RVM。nokogiri必需的库和头文件是什么?作为gem本身的文档:安装Nokogiri
如果您有问题，首先确保您拥有编译C扩展所需的所有工具:
sudo apt-get install build-essential patch
，然后可能需要这个:
sudo apt-get install ruby-dev zlib1g-dev liblzma-dev
当你在RVM上时，试试这个:
sudo apt-get install libgmp-dev
他们安装
gem install nokogiri