add support for macos (#81)

* add support for macos

* typo

Author: CommanderK5

libchecksum

@@ -1,5 +1,18 @@
 function checksum() {
-  md5sum $1 | awk '{ print $1 }'
+DIST=$(uname)
+
+case $DIST in
+  Darwin)
+    md5 $1 | tr -d " " | awk -F= {'print $2'}
+    ;;
+  Linux)
+    md5sum $1 | awk '{ print $1 }'
+   ;;
+  *)
+    echo "Unsupported distro $DIST"
+    exit 1
+  ;;
+esac
 }
 
 export -f checksum