pg gem 安装(postgresql94)

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