I tried to install pg gem and I have had this warning:
You need to install postgresql-server-dev-X.Y for building a server-side extension or libpq-dev for building a client-side application.
So I tried install libpq-dev package and I have had this warning:
libpq-dev : Depends: libpq5 (= 8.4.17-0squeeze1) but 9.1.9-1~bpo60+1 is to be installed
How to fix this?
This should let you install the package you need :) Just tried it myself, I am not sure you will need all the packages on the second line, try it and see :)
apt-get update
apt-get install libxslt-dev libxml2-dev libpam-dev libedit-dev
aptitude install -t squeeze-backports postgresql-server-dev-9.1
You must setup postgresql-server-dev-X.Y, where X.Y. your's servers version, and it will install libpq-dev and other servers variables at modules for server side developing. In my case it was
apt-get install postgresql-server-dev-9.5
Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: libmysqlclient18 mysql-common Use 'apt-get autoremove' to remove them. The following extra packages will be installed:
libpq-dev Suggested packages: postgresql-doc-10 The following NEW packages will be installed: libpq-dev postgresql-server-dev-9.5
来源：https://stackoverflow.com/questions/17183792/install-libpq-dev-package-error