PostgreSQL gem pg was unable to install

问题

My DB is PostgreSQL.I am on CENTOS.... While installing the pg gem I received the following error. I reinstalled to clear my YAML problem also, which didn't work, but it is just a warning. My main problem is the installation of the pg gem:

[root@vdimc04 ~]# gem install pg
/usr/local/lib/ruby/1.9.1/yaml.rb:56:in `<top (required)>':
It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.
Building native extensions.  This could take a while...
ERROR:  Error installing pg:
    ERROR: Failed to build gem native extension.

        /usr/local/bin/ruby 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/bin/ruby
    --with-pg
    --without-pg
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config


Gem files will remain installed in /usr/local/lib/ruby/gems/1.9.1/gems/pg-0.14.1 for inspection.
Results logged to /usr/local/lib/ruby/gems/1.9.1/gems/pg-0.14.1/ext/gem_make.out

I also tried with the following command, but to no use:

 gem install pg -- --with-pg-config=/usr/pgsql-9.1/bin/pg_config

回答1:

I got the same error on Centos. By googling I found two commands to use:

1. yum install postgresql-libs -- It gave me message saying, its already installed.
2. yum install postgresql-devel -- It solved my error related to pg_config for installing the 'pg' .gem.

Hope it helps :)

apos wrote: on Ubuntu 14.04 install:

1. apt-get install postgresql-server-dev-9.3 libpq-dev

回答2:

Here's my recipe for getting PostgreSQL, RVM, Ruby, Rails all up and running on CentOS

PostgreSQL

First, follow the instructions on http://wiki.postgresql.org/wiki/YUM_Installation to get PostgreSQL installed:

sudo vi /etc/yum.repos.d/CentOS-Base.repo

[base]
exclude=postgresql*

[updates]
exclude=postgresql*

Get the latest PGDG RPM file (for your platform/architecture), for example:

curl -O http://yum.postgresql.org/9.2/redhat/rhel-latest-x86_64/pgdg-redhat92-9.2-7.noarch.rpm

Then

sudo rpm -ivh pgdg-redhat92-9.2-7.noarch.rpm
sudo yum install -y postgresql92-server postgresql92-devel

Initialize the database:

sudo service postgresql-9.2 initdb

Configure /var/lib/pgsql/9.2/data/postgresql.conf and /var/lib/pgsql/9.2/data/pg_hba.conf as needed.

Start PostgreSQL server:

sudo service postgresql-9.2 start

RVM

sudo yum -y groupinstall "Development Tools"
sudo yum -y install zlib zlib-devel sqlite-devel httpd curl-devel httpd-devel apr-devel apr-util-devel mlocate man libxml2-devel libxslt-devel libffi-devel readline-devel

Note, NOT as root:

\curl -L get.rvm.io | sudo bash -s stable

Logout and back on. Afterwards, which rvm should reply with /usr/local/rvm/bin/rvm and type rvm|head -1 should say rvm is a function.

Ruby + Rails

rvm install 1.9.3 --with-openssl-dir=/usr
rvm use 1.9.3 --default
gem install rake
gem install rails

PostgreSQL gem

gem install pg -- --with-pg-config=/usr/pgsql-9.2/bin/pg_config

The --with-pg-config is somehow needed with my latest installation of CentOS, otherwise, gem install pg can't find pg_config. YMMV, but if you follow all the above to the letter (which I've done enough times in the past few months) just let me know if anything trips you up.

回答3:

try installing libpq package by doing:

sudo apt-get install libpq-dev

That package helps with pg gem and you should be fine after that :)

回答4:

Try This, the answer is not mine but it worked for me. Remember to point to where your Postgres.app application is:

bundle config build.pg --with-pg-config=/Applications/Postgres.app/Contents/MacOS/bin/pg_config

Then do

bundle update
bundle install

回答5:

$ sudo apt-get install libpq-dev
$ sudo apt-get install libdbd-pg-ruby1.8

then:

$ sudo apt-get install pg  

for CentOS please read the below link..

http://wiki.postgresql.org/wiki/YUM_Installation

To install pg in centOS

run this commands

bundle config build.pg 

gem install pg -v '0.12.0'

回答6:

Try to install postgresql server and corresponding libraries. Then install the pg gem. Then it will work for u

回答7:

My problem is before pg gem was already installed.. but it is not loading to bundle.. Now the solution is: when we are declaring a new application like 'rails new Demo' we have to include

'--database=postgresql'. so now the total command is: 'rails new Demo --database=postgresql'

Then the pg gem file will gets to bundle..

In bundle only one gem will gets store . either pg gem or sqlite3 gem..

Now edit the database.yml file accordingly.. thats it

回答8:

I got the same problem and I tried to install all dependencies, but all is useless. In the end, I had a try to use PostgreSQL9.3, not PostgreSQL9.4, and everything is fine.

回答9:

Using AWS Cloud 9 Linux:

sudo yum install postgresql-libs

then:

sudo yum install postgresql-devel

then:

gem update --system

if needed, then:

gem install bundler (Bundler 2.0)

then:

bundle install

回答10:

First install

sudo apt-get install postgresql postgresql-server-dev-9.1

Next install

sudo apt-get install libpq-dev

Then install gem install pg

来源：https://stackoverflow.com/questions/13702417/postgresql-gem-pg-was-unable-to-install