Make release sed command work on OSX

release.sh

@@ -26,7 +26,12 @@ update_changelog() {
 
   local match='## \[unreleased\] \- unreleased'
   local heading="## [$version] - $release_date"
-  sed -i "/$match/c $heading" CHANGELOG.md
+  case $OSTYPE in
+  darwin*)
+    sed -i '' -E "/$match/c $heading" CHANGELOG.md;;
+  *)
+    sed -i "/$match/c $heading" CHANGELOG.md;;
+  esac
 }
 
 remove_empty_sections() {
@@ -36,15 +41,25 @@ remove_empty_sections() {
     local first_word=`echo $str_after | head -n1 | cut -d " " -f1`
     if [ $first_word != "-" ]; then
       echo "Removing empty CHANGELOG section: $section"
-      sed -i "0,/### $section/{//d;}" CHANGELOG.md
+      case $OSTYPE in
+      darwin*)
+        sed -i '' -E "0,/### $section/{//d;}" CHANGELOG.md;;
+      *)
+        sed -i "0,/### $section/{//d;}" CHANGELOG.md;;
+      esac
     fi
   done
 }
 
 add_changelog_unreleased_section() {
   echo "Adding unreleased section to CHANGELOG"
   local replace='## [unreleased] - unreleased\n\n### Fixed\n\n\n### Added\n\n\n### Changed\n\n\n'
-  sed -i "/## \[$version\] \- $release_date/i $replace" CHANGELOG.md
+  case $OSTYPE in
+  darwin*)
+    sed -i '' -E "/## \[$version\] \- $release_date/i $replace" CHANGELOG.md;;
+  *)
+    sed -i "/## \[$version\] \- $release_date/i $replace" CHANGELOG.md;;
+  esac
 }