nix-prefetch-url: progressbar

src/nix-prefetch-url/nix-prefetch-url.cc

@@ -7,6 +7,8 @@
 #include "common-eval-args.hh"
 #include "attr-path.hh"
 #include "legacy.hh"
+#include "finally.hh"
+#include "progress-bar.hh"
 
 #include <iostream>
 
@@ -96,6 +98,11 @@ static int _main(int argc, char * * argv)
         if (args.size() > 2)
             throw UsageError("too many arguments");
 
+        Finally f([]() { stopProgressBar(); });
+
+        if (isatty(STDERR_FILENO))
+          startProgressBar();
+
         auto store = openStore();
         auto state = std::make_unique<EvalState>(myArgs.searchPath, store);