Linter when only python3 exists

Reviewed By: nikhilaravi

Differential Revision: D31289856

fbshipit-source-id: 5a522a69537a873bacacf2a178e5f30771aef35f

Author: bottler

dev/linter.sh

@@ -10,7 +10,10 @@
 {
   V=$(black --version|cut '-d ' -f3)
   code='import distutils.version; assert "19.3" < distutils.version.LooseVersion("'$V'")'
-  python -c "${code}" 2> /dev/null
+  PYTHON=false
+  command -v python > /dev/null && PYTHON=python
+  command -v python3 > /dev/null && PYTHON=python3
+  ${PYTHON} -c "${code}" 2> /dev/null
 } || {
   echo "Linter requires black 19.3b0 or higher!"
   exit 1