所以我正在阅读这个Rails教程，他们正在安装我们的应用程序。这样做我遇到了这个错误消息。在我运行rails new _4.2.2_ new toy_app并随后运行bundle install之后发出此消息。我也试过运行sudo gem install pg -v0.17.1命令无济于事。任何帮助将不胜感激！
Installing pg 0.17.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
/home/alopex/.rvm/rubies/ruby-2.2.1/bin/ruby -r ./siteconf20150710-6312-1vbswpn.rb extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
--with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** 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=/home/alopex/.rvm/rubies/ruby-2.2.1/bin/$(RUBY_BASE_NAME)
--with-pg
--without-pg
--with-pg-config
--without-pg-config
--with-pg_config
--without-pg_config
--with-pg-dir
--without-pg-dir
--with-pg-include
--without-pg-include=${pg-dir}/include
--with-pg-lib
--without-pg-lib=${pg-dir}/lib
extconf failed, exit code 1
Gem files will remain installed in /home/alopex/.rvm/gems/ruby-2.2.1/gems/pg-0.17.1 for inspection.
Results logged to /home/alopex/.rvm/gems/ruby-2.2.1/extensions/x86_64-linux/2.2.0/pg-0.17.1/gem_make.out
An error occurred while installing pg (0.17.1), and Bundler cannot continue.
Make sure that `gem install pg -v '0.17.1'` succeeds before bundling.
alopex@alopex-TH55-HD:~/work-space$ sudo gem install pg -v 0.17.1
Building native extensions. This could take a while...
ERROR: Error installing pg:
ERROR: Failed to build gem native extension.
/usr/bin/ruby1.9.1 extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
--with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** 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/ruby1.9.1
--with-pg
--without-pg
--with-pg-config
--without-pg-config
--with-pg_config
--without-pg_config
--with-pg-dir
--without-pg-dir
--with-pg-include
--without-pg-include=${pg-dir}/include
--with-pg-lib
--without-pg-lib=${pg-dir}/lib
Gem files will remain installed in /var/lib/gems/1.9.1/gems/pg-0.17.1 for inspection.
Results logged to /var/lib/gems/1.9.1/gems/pg-0.17.1/ext/gem_make.out