Fixed: installation on OS X fails

install

@@ -8,7 +8,13 @@ if [ ! -r ~/.zshrc ]; then
     exit 1
 fi
 
-DIR=$(dirname $(readlink -f $0)) ;
+SOURCE="${BASH_SOURCE[0]}"
+while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
+  DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
+  SOURCE="$(readlink "$SOURCE")"
+  [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
+done
+DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
 
 # appends the string to ~/.zshrc file
 cat >> ~/.zshrc << EOF