Prompt the user about checksums only if interactive.

1 files changed, 13 insertions, 6 deletions

diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index e7905cb410..bb6180c521 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -615,12 +615,19 @@ class Package(object):
         if spack.do_checksum and not self.version in self.versions:
             tty.warn("There is no checksum on file to fetch %s safely."
                      % self.spec.format('$_$@'))
-            ignore = tty.get_yes_or_no("  Fetch anyway?", default=False)
-            msg = "Add a checksum or use --no-checksum to skip this check."
-            if ignore:
-                tty.msg("Fetching with no checksum.", msg)
-            else:
-                raise FetchError("Will not fetch %s." % self.spec.format('$_$@'), msg)
+
+            # Ask the user whether to skip the checksum if we're
+            # interactive, but just fail if non-interactive.
+            checksum_msg = "Add a checksum or use --no-checksum to skip this check."
+            ignore_checksum = False
+            if sys.stdout.isatty():
+                ignore_checksum = tty.get_yes_or_no("  Fetch anyway?", default=False)
+                if ignore_checksum:
+                    tty.msg("Fetching with no checksum.", checksum_msg)
+
+            if not ignore_checksum:
+                raise FetchError(
+                    "Will not fetch %s." % self.spec.format('$_$@'), checksum_msg)
 
         self.stage.fetch()