Convert Irish Grid Coordinates to Latitude Longitude

On the OpenDataNI portal some of the data sources show X,Y co-ordinates for the Irish Grid reference system (EPSG:29902). I wanted to be able to convert these to latitude longitude values I could use with OpenStreetMap and the cs2cs tool from the

Install Proj (Linux)

apt install proj

Install Proj (Mac)

brew install proj

Usage

Run it with example co-ordinates:

echo "309639 328089" | cs2cs -d 4 EPSG:29902 EPSG:4326

And the output is:

54.1901	-6.3211 0.0000

Which I can then manipulate into a URL.