Fix build_tools/version.sh

build_tools/version.sh

@@ -1,12 +1,14 @@
+#!/bin/sh
 if [ $# == 0 ]; then
   echo "Usage: $0 major|minor|patch"
+  exit 1
 fi
-if [[ $1 == "major" ]]; then
+if [ $1 = "major" ]; then
   cat include/rocksdb/version.h  | grep MAJOR | head -n1 | awk '{print $3}'
 fi
-if [[ $1 = "minor" ]]; then
+if [ $1 = "minor" ]; then
   cat include/rocksdb/version.h  | grep MINOR | head -n1 | awk '{print $3}'
 fi
-if [[ $1 = "patch" ]]; then
+if [ $1 = "patch" ]; then
   cat include/rocksdb/version.h  | grep PATCH | head -n1 | awk '{print $3}'
 fi