Install dependencies on Ubuntu and Debian

For Ubuntu and Debian, there are prepackaged development binaries available. Install the GMT dependencies with:

# Update the package index
sudo apt-get update

# Install required dependencies
sudo apt-get install build-essential cmake libcurl4-gnutls-dev libnetcdf-dev

# Install optional dependencies
sudo apt-get install gdal-bin libgdal-dev libfftw3-dev libpcre3-dev liblapack-dev libblas-dev libglib2.0-dev ghostscript

# to enable movie-making
sudo apt-get install graphicsmagick ffmpeg

# to enable document viewing via gmt docs
sudo apt-get install xdg-utils

# to enable testing
sudo apt-get install graphicsmagick

# to build the documentation
sudo apt-get install python3-sphinx