list contents of directory

-l     List  in  long  format,  giving  mode (see below), file system type (e.g., for devices, the # code
       letter that names it; see intro(3)), the instance or  subdevice  number,  owner,  group,  size  in
       bytes, and time of last modification for each file.

-d     If argument is a directory, list it, not its contents.

Commands separated  by  a ; are executed sequentially; the shell waits for each command to terminate in turn.  The
return status is the exit status of the last command executed.

execute a command as another user

change file mode bits

The  format  of  a  symbolic  mode  is  [ugoa...][[+-=][perms...]...], where perms is either zero or more
letters from the set rwxXst, or a single letter from the set ugo.  Multiple symbolic modes can be  given,
separated by commas.

Change the mode of each FILE to MODE.