$ sudo apt-get update
$ sudo apt-get install libpgapack-serial1 

libpgapack-serial1 is installed in your system.

Make ensure the libpgapack-serial1 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libpgapack-serial1 *

You will get with libpgapack-serial1 package name, version, architecture and description in a table

libpgapack-serial1 package basic information: