Another try of drone

.drone.yml

@@ -4,9 +4,21 @@ type: docker
 name: default
 
 steps:
-    - name: lintr
+- name: lintr
-        image: jupyter/datascience-notebook
+  image: jupyter/datascience-notebook
-              commands:
+  commands:
-                  - Rscript -e 'devtools::install_github("jimhester/lintr")'
+  - export TAR="/bin/tar"
-                  - Rscript -e 'lintr::lint_package()'
+  - Rscript -e 'devtools::install_github("jimhester/lintr")'
-
+  # Lint the document, printing output.
+  - |
+    Rscript -e 'lintr::lint_dir(
+      path=".", pattern=rex::rex(".", one_of("Rr"), maybe("md"), end)
+    )'
+  # Return non-zero exit code (no output is printed).
+  - |
+    Rscript -e 'quit(
+      save="no",
+      status=length(
+        lintr::lint_dir(path=".", pattern=rex::rex(".", one_of("Rr"), maybe("md"), end))
+      )
+    )'