sudo apt-get install wget ca-certificates 
sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt trusty-pgdg main" >> /etc/apt/sources.list'
wget --quiet -O - http://apt.postgresql.org/pub/repos/apt/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install postgresql-9.4-postgis-2.1 pgadmin3 postgresql-contrib

但是我收到以下错误.

The following packages have unmet dependencies:
 pgadmin3 : Depends: libwxbase3.0-0 (>= 3.0.0) but it is not installable
            Depends: libwxgtk3.0-0 (>= 3.0.0) but it is not installable
            Recommends: pgagent but it is not going to be installed
 postgresql-9.4-postgis-2.1 : Depends: libgdal1h (>= 1.9.0) but it is not installable
                              Depends: libgeos-c1 (>= 3.4.2) but it is not installable
                              Depends: liblwgeom-2.1.5 (>= 2.1.2) but it is not going to be installed
                              Depends: libproj0 (>= 4.8.0-1) but it is not installable
E: Unable to correct problems,you have held broken packages.

我搜索了几个地方,看到了很多回复,但没有一个对我有用.我也试过Postgresql9.3并且也没能成功.谢谢你的帮助.谢谢