I have a bunch of shapefiles of which I know the projection (EPSG:28992). However, they did not come with a prj-file (.prj).
Rather than defining the projection and re-saving the files, I wonder whether it would be okay to copy (and rename) the prj-file from another shapefile which is in the same projection?
That has always worked fine for me.
Also if you know the projection but don't have an example to copy you can fetch one from http://epsg.io
Yes copying and renaming a .prj file is an adequate way of assigning projection to a shapefile.
But it could be safer/easier to do it differently as a typo during renaming may go unnoticed and cause the .prj to not be read.
(If you use ArcGIS setting a projection simply add the .prj and do not require to resave the file)
