使用下面命令安装报错
gem install pg
错误：
[root@AS-test middle_database]# gem install pg
Building native extensions. This could take a while...
ERROR: Error installing pg:
ERROR: Failed to build gem native extension.
current directory: /usr/local/rvm/gems/ruby-2.3.0/gems/pg-0.18.4/ext
/usr/local/rvm/rubies/ruby-2.3.0/bin/ruby -r ./siteconf20160413-9383-11d3dx6.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=/usr/local/rvm/rubies/ruby-2.3.0/bin/$(RUBY_BASE_NAME)
--with-pg
--without-pg
--enable-windows-cross
--disable-windows-cross
--with-pg-config
--without-pg-config
--with-pg_config
--without-pg_config
--with-pg-dir
--without-pg-dir
--with-pg-include
--without-pg-include=${pg-dir}/include
--with-pg-lib
--without-pg-lib=${pg-dir}/lib
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/pg-0.18.4/mkmf.log
extconf failed, exit code 1
网上搜索了一大片，说是需要安装postgresql-devel这个rpm.
于是安装94版本的：
yum install http://yum.postgresql.org/9.4/redhat/rhel-6-x86_64/pgdg-redhat94-9.4-1.noarch.rpm
yum install -y postgresql94-devel-9.4.6 #我主机postgresql 9.4.6的server已安装
然后再次执行上面的命令，还是报错，于是
gem install pg --with-pg-config=/usr/pgsql-9.4/bin/pg_config
接着报错：
ERROR: While executing gem ... (OptionParser::InvalidOption)
invalid option: --with-pg-config=/usr/pgsql-9.4/bin/pg_config
折腾许久，源来需要多加一个 --
gem install pg -- --with-pg-config=/usr/pgsql-9.4/bin/pg_config