add OS X sed check to update-submodule.sh
@@ -31,6 +31,22 @@ set -o errexit
set -o nounset
set -o pipefail
+# OS X sed doesn't support "--version". This way we can tell if OS X sed is
+# used.
+if ! sed --version &>/dev/null; then
+ # OS X sed and GNU sed aren't compatible with backup flag "-i". Namely
+ # sed -i ... - does not work on OS X
+ # sed -i'' ... - does not work on certain OS X versions
+ # sed -i '' ... - does not work on GNU
+ echo ">>> OS X sed detected, which may be incompatible with this script. Please install and use GNU sed instead:
+ $ brew install gnu-sed
+ $ brew info gnu-sed
+ # Find the path to the installed gnu-sed and add it to your PATH. The default
+ # is:
+ # PATH=\"/Users/\$USER/homebrew/opt/gnu-sed/libexec/gnubin:\$PATH\""
+ exit 1
+fi
+
repo_root="$(git rev-parse --show-toplevel)"
declare -r repo_root
cd "${repo_root}"
