sudo chmod -664 my_file

chmod 644 my_file

$ ls -l my_file
-rwxrwxrwx 1 terdon terdon 0 May 28 13:45 my_file

$ chmod -644 my_file; ls -l my_file
---x-wx-wx 1 terdon terdon 0 May 28 13:45 my_file

$ ls -l my_file
-rw-r--r-- 1 terdon terdon 0 May 28 13:45 my_file
$ chmod -644 my_file
$ ls -l my_file
---------- 1 terdon terdon 0 May 28 13:45 my_file