User Group Other
r--	 r--   r--
100	 100   100
4	 4	   4
rw-  rw-   r--
110	 110   100
6	 6	  4

r=Read
w=Write
X=Execute

Comando:

chmod permessi file
permessi=numero in ottale, esempio 777=rwx rwx rwx
                                   642=rw- r-- -w-