add option to overwrite

install.sh

@@ -1,10 +1,13 @@
 #!/bin/sh
 _install_dir="/usr/local/bin/"
 _uninstall=0
+_overwrite=0
 
 for _arg in "$@" ; do
   if [ "$_arg" = "-u" ] || [ "$_arg" = "--uninstall" ] ; then
     _uninstall=1
+  elif [ "$_arg" = "-o" ] || [ "$_arg" = "--overwrite" ] ; then
+    _overwrite=1
   else
     echo "warning: unknown option."
     exit 1
@@ -17,7 +20,7 @@ echo ""
 for _file in ./src/* ; do
   _destination="$_install_dir"$(basename "$_file")
   if [ $_uninstall -eq 0 ] ; then
-    if ! [ -e "$_destination" ] ; then
+    if [ ! -e "$_destination" ] || [ "$_overwrite" -eq 1 ] ; then
       echo "installing: $_file"
       sudo cp "$_file" "$_install_dir"
     else