Install SAGA GIS on a Mac (2019-10-30)

install-saga-mac

# If you haven't installed homebrew, see some instructions here: 
# https://github.com/bcgov/envreportutils/wiki/Macbook-Pro-Setup-for-Data-Science-at-EnvReportBC#homebrew
# These have not been tested on macOS Catalina, but the Mojave instructions _should_ work.
# If you run into issues, this looks like it might be helpful: 
# https://medium.com/faun/macos-catalina-xcode-homebrew-gems-developer-headaches-cf7b1edf10b7

# The osgeo homebrew tap is in a bit of a mess, so `brew install saga-gis` doesn't work (as of 2019-10-30). 
# This is because SAGA dependencies have been updated, but they haven't updated the brew formula for SAGA itself.
# Same goes for QGIS; and now that there is a fully self-contained signed installer, I recommend that over heomebrew for QGIS 
# (https://qgis.org/en/site/forusers/download.html)

# The following worked for me for SAGA:

# if you have only just installed homebrew or don't have these installed don't run this line:
brew unlink osgeo-gdal osgeo-proj osgeo-libspatialite osgeo-gdal-python

# Then run:
brew install https://raw.githubusercontent.com/OSGeo/homebrew-osgeo4mac/f6e7b27c7485afbdc5a8d9844231fd2e64f02659/Formula/osgeo-gdal.rb
brew install https://raw.githubusercontent.com/OSGeo/homebrew-osgeo4mac/b37f82142e347c293cf0b7992f6187d40116b2ca/Formula/osgeo-proj.rb
brew install https://raw.githubusercontent.com/OSGeo/homebrew-osgeo4mac/27f4ac2bc4056750307cee1b7a6abb9e33c846dd/Formula/osgeo-libspatialite.rb
brew install https://raw.githubusercontent.com/OSGeo/homebrew-osgeo4mac/de5db18027bc37cd3bb0d4be07f59fdc8fe55df9/Formula/osgeo-gdal-python.rb
brew install saga-gis --with-app

# The SAGA command-line tools will be installed, and the GUI will too at: /usr/local/opt/osgeo-saga/
# You can make the SAGA GUI available in your Applications folder by running:
ln -Fs `find $(brew --prefix) -name "SAGA.app"` /Applications/SAGA.app

# In R, RSAGA::rsaga.env() was able to find the SAGA installation, so that seems like a good sign!

Thanks @j-krogh... I'm not sure if you would have got this far without it, but just to be sure, do you have XCode command-line tools installed (xcode-select --install)? And/or try xcode-select --reset as suggested here?