Conditional Stata download

download.do

// this would be the directory to put data
global root : pwd
global data "$root/datadir" 
cap mkdir "$data" 
// now to the file in question
global nhtsfile "nhts-ascii.zip"
capture confirm file  "$data/$nhtsfile"
if _rc != 0 {
   // what to do when file does NOT exist
   copy https://nhts.ornl.gov/2009/download/Ascii.zip "$data/$nhtsfile"
}
// might want to also test for a "trigger" file
// to not unnecessarily unzip again
cd "$data" // Stata cannot unzip into a different directory, so we have to 
           // deviate from our rule to never use "cd" 
unzipfile "$nhtsfile"
cd "$root"